ORCID Profile
0000-0001-6576-726X
Current Organisation
University of Oxford
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Publisher: Oxford University Press (OUP)
Date: 08-2006
DOI: 10.1016/J.TRSTMH.2005.10.018
Abstract: A meta-analysis of rapid (</=60 min) dengue diagnostic assays was conducted to determine accuracy and identify causes of between-study heterogeneity. A systematic review identified 302 potentially suitable studies, of which 11 were selected for meta-analysis. All selected studies evaluated the immunochromatographic test (ICT) manufactured by Panbio Pty Ltd. In idual study results for sensitivity ranged from 0.45 to 1.0, specificity 0.57-1.0, diagnostic odds ratio 4.5-1287, and positive:negative likelihood ratios 2.3-59 and 0.01-0.56, respectively. Results indicated that the ICT evaluated in the selected studies can both rule in and rule out disease but is more accurate when s les are collected later in the acute phase of infection. Limitations of this meta-analysis were significant between-study heterogeneity caused by inconsistencies in evaluation methodologies, and the evaluation of only the Panbio ICT. It is recommended that additional, standardized evaluations are required for other dengue ICTs.
Publisher: Asian Australasian Association of Animal Production Societies
Date: 11-2017
DOI: 10.5713/AJAS.16.0887
Publisher: American Society for Microbiology
Date: 12-2011
DOI: 10.1128/CVI.05285-11
Abstract: Six assays were evaluated in this study to determine their suitability for the diagnosis of acute dengue infection using s les from 259 Sri Lankan patients with acute fevers (99 confirmed dengue cases and 160 patients with other confirmed acute febrile illnesses): (i) the Merlin dengue fever IgG & IgM combo device (Merlin), (ii) the Standard Diagnostics Dengue Duo nonstructural 1 (NS1) antigen and IgG/IgM combo device (Standard Diagnostics, South Korea), (iii) the Biosynex Immunoquick dengue fever IgG and IgM (Biosynex, France) assay, (iv) the Bio-Rad NS1 antigen strip (Bio-Rad, France), (v) the Panbio Dengue Duo IgG/IgM Cassette (Inverness, Australia), and (vi) the Panbio dengue NS1 antigen strip (Inverness, Australia). The median number of days of fever prior to admission s le collection was 5 days (interquartile range, 3 to 7 days). Sensitivity and specificity of the NS1 antigen tests ranged from 49 to 59% and from 93 to 99%, respectively, and sensitivity and sensitivity of the IgM antibody test ranged from 71 to 80% and from 46 to 90%, respectively. Combining the NS1 antigen and IgM antibody results from the Standard Diagnostics Dengue Duo test gave the best compromise of sensitivity and specificity (93% and 89%, respectively) and provided the best sensitivity in patients presenting at different times after fever onset. The Merlin IgM/IgG antibody tests correctly classified 64% and 86% of the primary and secondary dengue infection cases, respectively, and the Standard Diagnostics IgM/IgG antibody tests correctly classified 71% and 83% of the primary and secondary dengue infection cases, respectively. This study provides strong evidence of the value of combining dengue antigen- and antibody-based test results in the rapid diagnostic test (RDT) format for the acute diagnosis of dengue.
Publisher: Wildlife Disease Association
Date: 07-2009
DOI: 10.7589/0090-3558-45.3.740
Abstract: Wild bird surveillance for highly pathogenic avian influenza (HPAI) H5N1 virus from 2004 to 2007 in Thailand indicated that the prevalence of infection with avian influenza H5N1 virus in wild birds was low (1.0%, 95% confidence interval [CI]: 0.7-1.2, 60/6,263 pooled s les). However, the annual prevalence varied considerably over this period, with a peak of 2.7% (95% CI: 1.4, 4.1) in 2004. Prevalence dropped to 0.5% (95% CI: 0.3, 0.8]) and 0.6% (95% CI: 0.3, 1.0) in 2005 and 2006, respectively, and then increased to 1.8% (95% CI: 1.0, 2.6) in 2007. During this period, 16 species from 12 families of wild birds tested positive for H5N1 virus infection. All s les from juvenile birds were negative for H5N1 virus, whereas 0.6% (95% CI: 0.4, 0.9) of pooled s les from adult birds were positive. Most positive s les originated from peridomestic resident species. Infected wild bird s les were only found in provinces where poultry outbreaks had occurred. Detection of H5N1 virus infection in wild birds was reported up to 3 yr after eradication of the poultry outbreaks in those provinces. As observed with outbreaks in poultry, the frequencies of H5N1 outbreaks in wild birds were significantly higher in winter. Further understanding of the mechanisms of persistence and ongoing HPAI H5N1 transmission between wild birds and domestic poultry is needed.
Publisher: MDPI AG
Date: 29-10-2021
DOI: 10.3390/ANTIBIOTICS10111324
Abstract: Oregano essential oil (OEO) is a natural compound consisting of potent antibiotic molecules. Its volatility is the major obstacle against the transportation and anti-bacterial performance. In this work, submicron-sized vermiculite (SMV) particles were prepared from Australian vermiculite clay by ball milling, and tested as a potential particulate-carrier for OEO. The loading of OEO by SMV can be easily achieved by mechanical mixing. Compared to raw vermiculite and free OEO, the OEO-loaded SMV displayed sustained isothermal release behaviour of OEO and demonstrated enhanced antibacterial performance in in vitro antibacterial tests against Escherichia coli (E. coli) and Staphylococcus epidermidis (S. epidermidis). This study provides a facile and commercially viable approach in designing advantageous carriers for volatile actives in antimicrobial applications.
Publisher: American Chemical Society (ACS)
Date: 03-05-2021
Publisher: Elsevier BV
Date: 05-2009
DOI: 10.1016/J.VETMIC.2008.12.008
Abstract: Foot-and-mouth disease (FMD) causes sporadic disease outbreaks in the Lao People's Democratic Republic (Lao PDR) and appears to be endemic within a livestock population largely susceptible to infection. As Lao PDR is a major thoroughfare for transboundary animal movement, regular FMD outbreaks occur causing economic hardship for farmers and their families. The dominant serotype causing outbreaks between 1998 and 2006 was type O. Using phylogenetic analysis, type O isolated viruses were ided into two topotypes: South East Asia (SEA) and the Middle East-South Asia (ME-SA). Type A virus was reported only in 2003 and 2006 and type Asia 1 only in 1996 and 1998.
Publisher: O.I.E (World Organisation for Animal Health)
Date: 09-1992
Abstract: A survey of type O foot and mouth disease (FMD) virus isolates from northern Thailand was undertaken to determine the relationship between field viruses and the vaccine in use, and to gauge the range of antigenic variation among field viruses. Isolates were collected from the two most recent epizootics, 1986-1987 and 1989-1990, and assessed using a two-dimensional neutralisation test to determine their relationship to FMD type O1 Bangkok 1960 (O BKK/60) reference (vaccine challenge) virus. The critical r value for the survey was 0.259 and all isolates tested were found to have an r value considerably greater than this (range 0.66 to 0.80). The results showed close antigenic relationships between the isolates and the reference virus, and indicated a relatively small range of antigenic variation between the isolates.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 08-07-2015
Publisher: Public Library of Science (PLoS)
Date: 24-02-2015
Publisher: MDPI AG
Date: 06-03-2018
Publisher: Public Library of Science (PLoS)
Date: 12-04-2018
Publisher: Elsevier BV
Date: 08-1994
DOI: 10.1016/0166-0934(94)90056-6
Abstract: This communication describes the development and evaluation of a simple and rapid method for the classification of Australian orbiviruses into one of seven established serogroups (i.e. bluetongue, epizootic haemorrhagic disease of deer, Palyam, Eubenangee, Corriparta, Wallal, Warrego) or an 'ungrouped' category. The Australian orbivirus serogrouping ELISA (SG-ELISA) utilised a sodium deoxycholate-treated cell lysate preparation from infected BHK cells which was subsequently probed in an indirect ELISA format with polyclonal antibodies representative of each serogroup. Bound immunoglobulin was detected by the use of a recombinant streptococcal protein G-HRPO conjugate and subsequent reaction with the chromogenic substrate. All reference orbiviruses tested in the SG-ELISA were identified and were in agreement with the serogroups originally designated. Minimal inter-serogroup cross-reactions were observed. One-way cross-reactions were observed between Warrego and Mitchell River viruses.
Publisher: MDPI AG
Date: 11-11-2021
DOI: 10.3390/TROPICALMED6040199
Abstract: Rural areas usually show a higher prevalence of rickettsial infection than urban areas. However, information on the rickettsial infection status in urban settings (e.g., built-up areas and city parks) is still limited, particularly in the Bangkok metropolitan area. In this study, we performed a molecular rickettsial survey of spleen s les of small mammals caught in public parks and built-up areas of Bangkok. Out of 198 s les, the Rattus rattus complex was found to be most prevalent. The lification of rickettsial gltA fragment gene (338 bp) by nested PCR assay revealed positive results in four s les, yielding a low prevalence of infection of 2.02%. DNA sequencing results confirmed that three s les were matched with Rickettsia typhi, and one was identified as R. felis. It is noteworthy that this is the first report of the occurrence of R. felis DNA in rodents in Southeast Asia.
Publisher: Public Library of Science (PLoS)
Date: 06-2017
Publisher: Oxford University Press (OUP)
Date: 10-2012
Publisher: Public Library of Science (PLoS)
Date: 11-09-2017
Publisher: American Physiological Society
Date: 05-2006
DOI: 10.1152/JAPPLPHYSIOL.01439.2005
Abstract: Epidemiological studies link habitual snoring and stroke, but mechanisms involved are poorly understood. One previously advanced hypothesis is that transmitted snoring vibration energy may promote carotid atheromatous plaque formation or rupture. To test whether vibration energy is present in carotid artery walls during snoring we developed an animal model in which we examined induced snoring (IS)-associated tissue energy levels. In six male, supine, anesthetized, spontaneously breathing New Zealand White rabbits, we surgically inserted pressure transducer-tipped catheters (Millar) to monitor tissue pressure at the carotid artery bifurcation (P CT ) and within the carotid sinus lumen (P CS artery ligated). Snoring was induced via external compression (sandbag) over the pharyngeal region. Data were analyzed using power spectral analysis for frequency bands above and below 50 Hz. For frequencies below 50 Hz, P CT energy was 2.2 (1.1–12.3) cmH 2 O 2 [median (interquartile range)] during tidal breathing (TB) increasing to 39.0 (2.5–95.0) cmH 2 O 2 during IS ( P = 0.05, Wilcoxon's signed-rank test). For frequencies Hz, P CT energy increased from 9.2 (8.3–10.4) × 10 −4 cmH 2 O 2 during TB to 172.0 (118.0–569.0) × 10 −4 cmH 2 O 2 during IS ( P = 0.03). Concurrently, P CS energy was 13.4 (8.5–18.0) × 10 −4 cmH 2 O 2 during TB and 151.0 (78.2–278.8) × 10 −4 cmH 2 O 2 during IS ( P 0.03). The P CS energy was greater than P CT energy for the 100–275 Hz bandwidth. In conclusion, during IS there is increased energy around and within the carotid artery, including lower frequency lification for P CS . These findings may have implications for carotid atherogenesis and/or plaque rupture.
Publisher: Elsevier BV
Date: 08-2011
DOI: 10.1016/J.MEEGID.2011.04.022
Abstract: The objective of this study was to determine the prevalence and genotypic range of Hepatitis E virus (HEV) in the pig population of northern Lao People's Democratic Republic (PDR). We collected 181 faecal s les from indigenous-breed pigs ≤ 6 months of age and the faeces was stored in RNA stabilisation buffer due to cold-chain and transport limitations. Twenty-one (11.6%) pigs had detectable HEV RNA and 43.5% of village pig herds were infected. Based on a 240 base pair-nucleotide sequence flanking the junction of open reading frames 1, 2 and 3 (ORF1, ORF2 and ORF3) the isolates were phylogenetically classified within genotype 4. Phylogenetic analyses revealed distinct genetic groupings of the Lao HEV isolates and two groups clustered with human and pig HEV isolates from China. This was the first study to demonstrate genotype 4 HEV in Lao PDR and indicates pigs are a potential reservoir for human HEV infection.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 08-2012
Publisher: Mary Ann Liebert Inc
Date: 09-2023
Publisher: Elsevier BV
Date: 06-2004
Publisher: Acoustical Society of America
Date: 2016
DOI: 10.1121/2.0000400
Publisher: Elsevier BV
Date: 03-2018
Publisher: Hindawi Limited
Date: 2012
DOI: 10.1155/2012/512969
Publisher: Public Library of Science (PLoS)
Date: 29-08-2013
Publisher: Hindawi Limited
Date: 2012
DOI: 10.1155/2012/151967
Abstract: Dengue fever, dengue haemorrhagic fever, and dengue shock syndrome (DF/DHF/DSS) are tropical diseases that cause significant humanitarian and economic hardship. It is estimated that more than 2.5 billion people are at risk of infection and more than 100 countries have endemic dengue virus transmission. Laboratory tests are essential to provide an accurate diagnosis of dengue virus infection so that appropriate treatment and patient management may be administered. In many dengue endemic settings, laboratory diagnostic resources are limited and simple rapid diagnostic tests (RDTs) provide opportunities for point-of-care diagnosis. This paper addresses current issues relating to the application of commercial dengue RDTs for the diagnosis of acute dengue virus infection, recent diagnostic evaluations, and identifies future needs.
Publisher: American Society for Microbiology
Date: 06-2016
DOI: 10.1128/JCM.02744-15
Abstract: The enzyme-linked immunosorbent assay (ELISA) has been proposed as an alternative serologic diagnostic test to the indirect immunofluorescence assay (IFA) for scrub typhus. Here, we systematically determine the optimal s le dilution and cutoff optical density (OD) and estimate the accuracy of IgM ELISA using Bayesian latent class models (LCMs). Data from 135 patients with undifferentiated fever were reevaluated using Bayesian LCMs. Every patient was evaluated for the presence of an eschar and tested with a blood culture for Orientia tsutsugamushi , three different PCR assays, and an IgM IFA. The IgM ELISA was performed for every s le at s le dilutions from 1:100 to 1:102,400 using crude whole-cell antigens of the Karp, Kato, and Gilliam strains of O. tsutsugamushi developed by the Naval Medical Research Center. We used Bayesian LCMs to generate unbiased receiver operating characteristic curves and found that the s le dilution of 1:400 was optimal for the IgM ELISA. With the optimal cutoff OD of 1.474 at a s le dilution of 1:400, the IgM ELISA had a sensitivity of 85.7% (95% credible interval [CrI], 77.4% to 86.7%) and a specificity of 98.1% (95% CrI, 97.2% to 100%) using paired s les. For the ELISA, the OD could be determined objectively and quickly, in contrast to the reading of IFA slides, which was both subjective and labor-intensive. The IgM ELISA for scrub typhus has high diagnostic accuracy and is less subjective than the IgM IFA. We suggest that the IgM ELISA may be used as an alternative reference test to the IgM IFA for the serological diagnosis of scrub typhus.
Publisher: Elsevier BV
Date: 02-2015
Publisher: MDPI AG
Date: 25-07-2019
DOI: 10.3390/TROPICALMED4030111
Abstract: The endemicity of Dengue virus (DENV) infection remains a major public health problem in Lao PDR. In this study, we compared two commercial anti-dengue IgM ELISA kits, Panbio® Dengue IgM Capture ELISA (Panbio Kit, Alere, Waltham, MA, USA) and DEN DetectTM MAC-ELISA (InBios kit, InBios International, Inc., Seattle, WA, USA), in the context of diagnosis of patients admitted to hospital with clinical dengue presentation. Two panels of paired blood s les were tested. Panel A was composed of 54 dengue confirmed patients (by DENV real-time RT-PCR) and 11 non-dengue dengue patients (other infections confirmed by corresponding PCR results). Panel B included 74 patients randomly selected from consecutive patients admitted to Mahosot Hospital in 2008 with suspicion of dengue fever according to WHO criteria. Results from panel A showed significantly better sensitivity for Panbio kit (64.8% 95%CI: 50.6–77.3%) than for InBios kit (18.5% 95%CI: 9.3–31.4%) when testing admission sera. Sensitivity was increased for both kits when combining results from admission and convalescent sera. Concordant results were obtained from panel B with fair agreement (κ = 0.29) between both kits when testing single admission s les, and moderate agreement (κ = 0.5) when combining results from admission and convalescent sera.
Publisher: Public Library of Science (PLoS)
Date: 26-04-2021
DOI: 10.1371/JOURNAL.PNTD.0009359
Abstract: Dengue is the world’s most common mosquito-borne virus but remains diagnostically challenging due to its nonspecific presentation. Access to laboratory confirmation is limited and thus most reported figures are based on clinical diagnosis alone, the accuracy of which is uncertain. This systematic review assesses the diagnostic accuracy of the traditional (1997) and revised (2009) WHO clinical case definitions for dengue fever, the basis for most national guidelines. PubMed, EMBASE, Scopus, OpenGrey, and the annual Dengue Bulletin were searched for studies assessing the diagnostic accuracy of the unmodified clinical criteria. Two reviewers (NR/SL) independently assessed eligibility, extracted data, and evaluated risk of bias using a modified QUADAS-2. Additional records were found by citation network analysis. A meta-analysis was done using a bivariate mixed-effects regression model. Studies that modified criteria were analysed separately. This systematic review protocol was registered on PROSPERO (CRD42020165998). We identified 11 and 12 datasets assessing the 1997 and 2009 definition, respectively, and 6 using modified criteria. Sensitivity was 93% (95% CI: 77–98) and 93% (95% CI: 86–96) for the 1997 and 2009 definitions, respectively. Specificity was 29% (95% CI: 8–65) and 31% (95% CI: 18–48) for the 1997 and 2009 definitions, respectively. Diagnostic performance suffered at the extremes of age. No modification significantly improved accuracy. Diagnostic accuracy of clinical criteria is poor, with significant implications for surveillance and public health responses for dengue control. As the basis for most reported figures, this has relevance to policymakers planning resource allocation and researchers modelling transmission, particularly during COVID-19.
Publisher: Oxford University Press (OUP)
Date: 12-2008
DOI: 10.1016/J.TRSTMH.2008.04.040
Abstract: We present a loop-mediated isothermal PCR assay (LAMP) targeting the groEL gene, which encodes the 60kDa heat shock protein of Orientia tsutsugamushi. Evaluation included testing of 63 s les of contemporary in vitro isolates, buffy coats and whole blood s les from patients with fever. Detection limits for LAMP were assessed by serial dilutions and quantitation by real-time PCR assay based on the same target gene: three copies/microl for linearized plasmids, 26 copies/microl for VERO cell culture isolates, 14 copies/microl for full blood s les and 41 copies/microl for clinical buffy coats. Based on a limited s le number, the LAMP assay is comparable in sensitivity with conventional nested PCR (56kDa gene), with limits of detection well below the range of known admission bacterial loads of patients with scrub typhus. This inexpensive method requires no sophisticated equipment or s le preparation, and may prove useful as a diagnostic assay in financially poor settings however, it requires further prospective validation in the field setting.
Publisher: American Physiological Society
Date: 15-03-2015
DOI: 10.1152/JAPPLPHYSIOL.00691.2014
Abstract: Mechanical processes underlying pharyngeal closure have not been examined. We hypothesized that the pharyngeal mucosal surface would fold during closure, and lowering the upper airway lining liquid surface tension would unfold areas of mucosal apposition, i.e., folds. We compared baseline pharyngeal fold numbers and response to reduction in upper airway liquid surface tension in healthy and obstructive sleep apnea (OSA) subjects. Awake, gated magnetic resonance pharyngeal airway images of 10 healthy and 11 OSA subjects were acquired before and after exogenous surfactant administration (beractant). Upper airway liquid surface tension was measured at the beginning and end of image acquisition and averaged. Velopharyngeal and oropharyngeal images were segmented and analyzed separately for average cross-sectional area, circumference, and fold number. Compared with healthy subjects, at baseline, velopharynx for OSA subjects had a smaller cross-sectional area (98.3 ± 32.5 mm 2 healthy, 52.3 ± 23.6 mm 2 OSA) and circumference (46.5 ± 8.1 mm healthy, 30.8 ± 6.1 mm OSA both P 0.05, unpaired t-test), and fewer folds (4.9 ± 1.6 healthy, 3.1 ± 1.8 OSA, P 0.03). There were no differences in oropharynx for cross-sectional area, circumference, or folds. Reduction in upper airway liquid surface tension from 61.3 ± 1.2 to 55.3 ± 1.5 mN/m ( P 0.0001) did not change cross-sectional area or circumference for velopharynx or oropharynx in either group however, in OSA subjects, oropharyngeal folds fell from 6.8 ± 3.1 to 4.7 ± 1.2 ( n = 8, P 0.05), and velopharyngeal folds from 3.3 ± 1.9 to 2.3 ± 1.2 ( P = 0.08), and were unchanged in healthy subjects. Subjects with OSA have fewer velopharyngeal wall folds, which decrease further when surface tension falls. We speculate that reduced pharyngeal wall folds contribute to an increase in pharyngeal collapsibility.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 06-2012
Publisher: Springer Science and Business Media LLC
Date: 16-02-2013
DOI: 10.1007/S10393-013-0821-Y
Abstract: The parasitic zoonoses human cysticercosis (Taenia solium), taeniasis (other Taenia species) and trichinellosis (Trichinella species) are endemic in the Lao People's Democratic Republic (Lao PDR). This study was designed to quantify the economic burden pig-associated zoonotic disease pose in Lao PDR. In particular, the analysis included estimation of the losses in the pork industry as well as losses due to human illness and lost productivity. A Markov-probability based decision-tree model was chosen to form the basis of the calculations to estimate the economic and public health impacts of taeniasis, trichinellosis and cysticercosis. Two different decision trees were run simultaneously on the model's human cohort. A third decision tree simulated the potential impacts on pig production. The human capital method was used to estimate productivity loss. The results found varied significantly depending on the rate of hospitalisation due to neurocysticerosis. This study is the first systematic estimate of the economic impact of pig-associated zoonotic diseases in Lao PDR that demonstrates the significance of the diseases in that country.
Publisher: American Society for Microbiology
Date: 02-2015
DOI: 10.1128/CVI.00553-15
Abstract: In this study, we examined the diagnostic accuracy of the InBios Scrub Typhus Detect IgM enzyme-linked immunosorbent assay (ELISA) and determined the optimal diagnostic optical density (OD) cutoffs for screening and diagnostic applications based on prospectively collected, characterized s les from undifferentiated febrile illness patients in northern Thailand. Direct comparisons with the serological gold standard, indirect immunofluorescence assay (IFA), revealed strong statistical correlation of ELISA OD values and IFA IgM titers. Determination of the optimal ELISA cutoff for seroepidemiology or screening purposes compared to the corresponding IFA reciprocal titer of 400 as previously described for Thailand was 0.60 OD, which corresponded to a sensitivity (Sn) of 84% and a specificity (Sp) of 98%. The diagnostic performance against the improved and more-stringent scrub typhus infection criteria (STIC), correcting for low false-positive IFA titers, resulted in an Sn of 93% and an Sp of 91% at an ELISA cutoff of 0.5 OD. This diagnostic ELISA cutoff corresponds to IFA reciprocal titers of 1,600 to 3,200, which greatly reduces the false-positive rates associated with low-positive IFA titers. These data are in congruence with the recently improved serodiagnostic positivity criteria using the Bayesian latent class modeling approach. In summary, the InBios Scrub Typhus Detect IgM ELISA is affordable and easy-to-use, with adequate diagnostic accuracy for screening and diagnostic purposes, and should be considered an improved alternative to the gold standard IFA for acute diagnosis. For broader application, regional cutoff validation and antigenic composition for consistent diagnostic accuracy should be considered.
Publisher: Hindawi Limited
Date: 10-01-2019
DOI: 10.1111/TBED.13109
Publisher: The American Association of Immunologists
Date: 08-2020
Abstract: East Coast fever (ECF), caused by Theileria parva, is the most important tick-borne disease of cattle in sub-Saharan Africa. Practical disadvantages associated with the currently used live-parasite vaccine could be overcome by subunit vaccines. An 80-aa polypeptide derived from the C-terminal portion of p67, a sporozoite surface Ag and target of neutralizing Abs, was the focus of the efforts on subunit vaccines against ECF and subjected to several vaccine trials with very promising results. However, the vaccination regimen was far from optimized, involving three inoculations of 450 μg of soluble p67C (s-p67C) Ag formulated in the Seppic adjuvant Montanide ISA 206 VG. Hence, an improved formulation of this polypeptide Ag is needed. In this study, we report on two nanotechnologies that enhance the bovine immune responses to p67C. In idually, HBcAg-p67C (chimeric hepatitis B core Ag virus-like particles displaying p67C) and silica vesicle (SV)–p67C (s-p67C adsorbed to SV-140-C18, octadecyl-modified SVs) adjuvanted with ISA 206 VG primed strong Ab and T cell responses to p67C in cattle, respectively. Coimmunization of cattle (Bos taurus) with HBcAg-p67C and SV-p67C resulted in stimulation of both high Ab titers and CD4 T cell response to p67C, leading to the highest subunit vaccine efficacy we have achieved to date with the p67C immunogen. These results offer the much-needed research depth on the innovative platforms for developing effective novel protein-based bovine vaccines to further the advancement.
Publisher: Microbiology Society
Date: 09-2017
Abstract: A rickettsial organism harboured by Amblyomma triguttatum ticks on Barrow Island, Western Australia, was discovered after reports of possible rickettsiosis among local workers. Subsequent isolation of this rickettsia (strain BWI-1) in cell culture and analysis of its phylogenetic, genotypic and phenotypic relationships with type strains of Rickettsia species with standing in nomenclature suggested that it was sufficiently ergent to warrant its classification as a new species. Multiple gene comparison of strain BWI-1 revealed degrees of sequence similarity with Rickettsia raoultii, its closest relative, of 99.58, 98.89, 97.03, 96.93 and 95.73 % for the 16S rRNA, citrate synthase, ompA, ompB and sca4 genes, respectively. Serotyping in mice also demonstrated that strain BWI-1T was distinct from Rickettsia raoultii. Thus, we propose the naming of a new species, Rickettsia gravesii sp. nov., based on its novel genotypic and phenotypic characteristics. Strain BWI-1T was deposited in the ATCC, CSUR and ARRL collections under reference numbers VR-1664, CSUR R172 and RGBWI-1, respectively.
Publisher: Wiley
Date: 08-1999
DOI: 10.1111/J.1751-0813.1999.TB12127.X
Abstract: To determine the cause of an epidemic of blindness in kangaroos. Laboratory examinations were made of eyes and brains of a large number of kangaroos using serological, virological, histopathological, electron microscopical, immunohistochemical methods, and PCR with cDNA sequencing. In addition, potential insect viral vectors identified during the disease outbreak were examined for specific viral genomic sequences. For histopathological analysis, 55 apparently blind and 18 apparently normal wild kangaroos and wallabies were obtained from New South Wales, Victoria, South Australia, and Western Australia. A total of 437 wild kangaroos and wallabies (including 23 animals with apparent blindness) were examined serologically. Orbiviruses of the Wallal and Warrego serogroups were isolated from kangaroos affected with blindness in a major epidemic in south-eastern Australia in 1994 and 1995 and extending to Western Australia in 1995/96. Histopathological examinations showed severe degeneration and inflammation in the eyes, and mild inflammation in the brains. In affected retinas, Wallal virus antigen was detected by immunohistochemical analysis and orbiviruses were seen in electron microscopy. There was serological variation in the newly isolated Wallal virus from archival Wallal virus that had been isolated in northern Australia. There were also variations of up to 20% in genotype sequence from the reference archival virus. Polymerase chain reactions showed that Wallal virus was present during the epidemic in three species of midges, Culicoides austropalpalis, C dycei and C marksi. Wallal virus nucleic acid was also detected by PCR in a paraffin-embedded retina taken from a blind kangaroo in 1975. Wallal virus and perhaps also Warrego virus are the cause of the outbreak of blindness in kangaroos. Other viruses may also be involved, but the evidence in this paper indicates a variant of Wallal virus, an orbivirus transmitted by midges, has the strongest aetiological association, and immunohistochemical analysis implicates it as the most damaging factor in the affected eyes.
Publisher: Elsevier BV
Date: 03-2023
Publisher: MDPI AG
Date: 13-07-2022
DOI: 10.3390/TROPICALMED7070134
Abstract: The authors wish to make the following correction to this paper [...]
Publisher: Informa UK Limited
Date: 06-2006
DOI: 10.1080/03079450600714510
Abstract: The tropism of a Thailand strain of highly pathogenic avian influenza H5N1 virus was demonstrated on tissues (lung, trachea, heart, liver, spleen, pancreas, rectum, kidney, brain, skeletal muscle, duodenum, and oviduct) from naturally infected native chickens (Gallus gallus), Japanese quail (Coturnix coturnix japonica) and ducks (Anas spp.) by indirect immunofluorescence assay. In chickens and quail, the distribution and localization of nucleoprotein viral antigen was similar and detected at the highest level in cardiac myocytes, at 88% (chickens) and 89% (quail), and respiratory, digestive and urinary systems all showed high levels of antigen. Antigen in duck tissues were detected at significantly lower levels (P < 0.05) with the exception of brain and skeletal muscle s les. In most cases, antigen in duck tissue was absent in the digestive organs but present in respiratory organs, which supports the hypothesis that aerosol and oral-oral transmission are the main method of highly pathogenic avian influenza virus transmission from this species.
Publisher: Centers for Disease Control and Prevention (CDC)
Date: 08-2014
Publisher: American Society of Tropical Medicine and Hygiene
Date: 02-07-2012
Publisher: Oxford University Press (OUP)
Date: 12-2016
DOI: 10.5665/SLEEP.6304
Publisher: Elsevier BV
Date: 11-1991
DOI: 10.1016/0378-1135(91)90131-X
Abstract: The isolation of a monoclonal antibody (1G9/C9) with specificity for the epizootic haemorrhagic disease (EHD) serogroup has enabled the development of a highly sensitive and specific blocking ELISA (B-ELISA) for the detection of serum antibodies to EHD viruses. The assay was sensitive to blocking antibodies present in hyperimmune reference antisera to all six EHD serotypes tested but was unaffected by reference antisera to 19 South African and eight Australian serotypes of the related orbivirus bluetongue virus (BTV). The sensitivity of the EHD B-ELISA exceeded that of an indirect ELISA (I-ELISA) for EHD-specific antibody detection. Serum antibody titres to BTV and EHD in experimental and field sera, including a sentinel herd from which virus isolations were made, were examined in both the BTV and EHD B-ELISA tests. These results showed the B-ELISA was only sensitive to antibodies specific for the homologous serogroup in each case, even where sequential and mixed infections with each virus type occurred.
Publisher: Oxford University Press (OUP)
Date: 2011
Publisher: Public Library of Science (PLoS)
Date: 07-12-2020
DOI: 10.1371/JOURNAL.PNTD.0008858
Abstract: Scrub typhus is a major cause of morbidity and mortality in Southeast Asia. Diagnosis of scrub typhus is difficult due to a lack of accessible validated diagnostic tools. Despite its objectivity, the diagnostic accuracy of ELISA tests is influenced by methodological and patient factors. This study aims to evaluate the performance of a novel in-house ELISA developed in the Mahidol Oxford Tropical Medicine Research Unit (MORU) for anti-scrub typhus group IgM and IgG compared to the “gold standard” reference IFA and PCR, and to determine whether the in-house ELISA can be used as a seroepidemiological screening tool and/or stand-alone test for scrub typhus. A total of 1,976 admission and 1,438 participant follow-up sera collected in the Lao PDR (Laos) were tested with ELISA for IgM and IgG. S les with an ELISA OD≥0.50 were tested with IFA for IgM and/or IgG. A strong positive relationship was present between ELISA ODs and IFA titers for admission IgM ( r 2 : 0.70, p .005) and IgG ( r 2 : 0.76, p .005), and for follow-up IgM and IgG (both r 2 : 0.76, p .005) s les. The best compromise between sensitivity and specificity for the ELISA OD cut-off is likely to be between 0.8–1.0 for IgM antibodies and 1.2–1.8 for IgG antibodies. These results demonstrate that the diagnostic accuracy of the MORU in-house scrub typhus group ELISA is comparable to that of IFA, with similar results as reported for the commonly used InBios Scrub Typhus Detect ELISA, validating the use of the in-house ELISA. The optimal ELISA cut-off would depend on the use of the test, and the desired sensitivity and specificity. Further studies are required to authenticate the use of these cut-offs in other endemic regions. This in-house ELISA has the potential to replace the imperfect IFA, which could ultimately reduce the burden of scrub typhus by improving the rate of scrub typhus diagnoses in endemic low-resource areas.
Publisher: American Society for Microbiology
Date: 02-2010
DOI: 10.1128/CVI.00448-08
Abstract: Using archived s les, we assessed the diagnostic capacity of a rapid immunochromatographic test (ICT) for the detection of Orientia tsutsugamushi IgM and total antibodies to aid with the diagnosis of acute scrub typhus infection in febrile patients in Laos. The sensitivity and the specificity of the ICT for the detection of IgM were 96.8% (121/125 s les 95% confidence interval [CI], 92.1 to 99.1%) and 93.3% (98/105 s les 95% CI, 86.7 to 97.3%), respectively. For the detection of total antibodies, the sensitivity was 97.6% (122/125 s les 95% CI, 93.1 to 99.5%), but the specificity was much lower, at 71.4% (75/105 s les 95% CI, 61.8 to 79.8%).
Publisher: Public Library of Science (PLoS)
Date: 27-01-2017
Publisher: Springer Science and Business Media LLC
Date: 23-09-2022
DOI: 10.1007/S11250-022-03309-1
Abstract: A pilot animal disease surveillance program was implemented at four abattoirs in Phnom Penh, Cambodia, between October 2019 and January 2020. A total of 1141 s les were collected from 477 cattle and 664 swine. Serological testing was performed using commercial antibody ELISA kits for zoonotic and high-impact animal diseases, namely brucellosis, Q fever, classical swine fever (CSF), porcine reproductive and respiratory syndrome (PRRS) and African swine fever (ASF). Only two s les tested positive for Brucella antibodies (0.2%, 95% CI 0.4–0.6, n = 1141). The seroprevalence of Q fever was 0.8% (95% CI 0.3–2.1, n = 477) in the cattle s les, while CSF, PRRS and ASF in pigs were 55.4% (95% CI 51.6–59.2, n = 655), 81.2% (95% CI 78.1–84.0, n = 655) and 2.6% (95% CI 1.6–4.1, n = 664), respectively. All 38 doubtful and 17 positive ASF antibody ELISA s les were negative when tested by real-time PCR. Univariate analyses demonstrated that the factor significantly associated with positive results of ASF was the abattoir location ( p -value = 0.002). Based on logistic regression models, significant risk factors for CSF were province of origin ( p -value = 1.7 × 10 −6 ), abattoir ( p -value = 3.6 × 10 −11 ) and PRRS positivity ( p -value = 0.004), and for PRRS were province of origin ( p -value = 0.0004) and CSF positivity ( p -value = 0.001). In conclusion, the seroprevalences of zoonotic diseases in this study were very low. The high prevalence of CSF and PRRS antibodies were most likely the result of vaccination. All ASF seropositive pigs, including those that gave equivocal results, originated from large-scale Cambodian-based commercial farms, as well as Thailand, which raises questions about possible illegal vaccination or low-pathogenicity ASF variants. The pilot abattoir serological surveillance program described here has the potential to provide a sentinel for incursions of novel and endemic pathogens, although further work is required to demonstrate its capacity to provide information on the longitudinal disease trends.
Publisher: Elsevier BV
Date: 03-2012
Publisher: American Physiological Society
Date: 03-2017
DOI: 10.1152/JAPPLPHYSIOL.00764.2016
Abstract: Macroscopic pharyngeal anatomical abnormalities are thought to contribute to the pathogenesis of upper airway (UA) obstruction in obstructive sleep apnea (OSA). Microscopic changes in the UA mucosal lining of OSA subjects are reported however, the impact of these changes on UA mucosal surface topography is unknown. This study aimed to 1) develop methodology to measure UA mucosal surface topography, and 2) compare findings from healthy and OSA subjects. Ten healthy and eleven OSA subjects were studied. Awake, gated (end expiration), head and neck position controlled magnetic resonance images (MRIs) of the velopharynx (VP) were obtained. VP mucosal surfaces were segmented from axial images, and three-dimensional VP mucosal surface models were constructed. Curvature analysis of the models was used to study the VP mucosal surface topography. Principal, mean, and Gaussian curvatures were used to define surface shape composition and surface roughness of the VP mucosal surface models. Significant differences were found in the surface shape composition, with more saddle/spherical and less flat/cylindrical shapes in OSA than healthy VP mucosal surface models ( P 0.01). OSA VP mucosal surface models were also found to have more mucosal surface roughness ( P 0.0001) than healthy VP mucosal surface models. Our novel methodology was utilized to model the VP mucosal surface of OSA and healthy subjects. OSA subjects were found to have different VP mucosal surface topography, composed of increased irregular shapes and increased roughness. We speculate increased irregularity in VP mucosal surface may increase pharyngeal collapsibility as a consequence of friction-related pressure loss. NEW & NOTEWORTHY A new methodology was used to model the upper airway mucosal surface topography from magnetic resonance images of patients with obstructive sleep apnea and healthy adults. Curvature analysis was used to analyze the topography of the models, and a new metric was derived to describe the mucosal surface roughness. Increased roughness was found in the obstructive sleep apnea vs. healthy group, but further research is required to determine the functional effects of the measured difference on upper airway airflow mechanics.
Publisher: Oxford University Press (OUP)
Date: 22-08-2018
DOI: 10.1093/SLEEP/ZSY160
Publisher: American Physiological Society
Date: 11-2010
DOI: 10.1152/JAPPLPHYSIOL.00096.2010
Abstract: We studied the impact of wall strain and surrounding pressure on the onset of airflow limitation in a thin-walled “floppy” tube model. A vacuum source-generated steady-state (baseline) airflow (0–350 ml/s) through a thin-walled latex tube (length 80 mm, wall thickness 0.23 mm) enclosed within a rigid, sealed, air-filled, cylindrical chamber while upstream minus downstream pressure, chamber pressure (Pc), and lumen geometry [in-line digital camera segmentation (Amira 5.2.2) and analysis (Rhinoceros 4) software] were monitored. Longitudinal strain (S 0–62.5%) and Pc (0–20 cmH 2 O) combinations were imposed, and Pc associated with onset of 1) reduced airflow and 2) fully developed airflow limitation recorded. At any strain, increasing Pc resulted in a decrease in airflow. Across all baseline airflow, threshold pressure was 1–7 cmH 2 O for S 25%, 6–8 cmH 2 O at S = 25% and 37.5%, and 5–7 cmH 2 O at S = 50% and 62.5%. Pc associated with fully developed airflow limitation was 4–6 cmH 2 O for S 25%, cmH 2 O at S = 25% (i.e., no flow limitation), 18 cmH 2 O at S = 37.5%, and 8–12 cmH 2 O at S = 50% and 62.5%. Lumen area decreased with increasing Pc but was 1) larger at S = 25% and 2) characterized by bifold narrowing at S 25% and trifold narrowing at S ≥ 25%. In conclusion, tube function was modulated by Pc vs. S interactions, with S = 25% producing trifold lumen narrowing, maximal patency, and no airflow limitation. Findings may have implications for understanding peripharyngeal tissue pressure and pharyngeal wall strain effects on passive pharyngeal airway function in humans.
Publisher: American Society for Microbiology
Date: 05-2012
DOI: 10.1128/CVI.05717-11
Abstract: Seven commercial assays were evaluated to determine their suitability for the diagnosis of acute dengue infection: (i) the Panbio dengue virus Pan-E NS1 early enzyme-linked immunosorbent assay (ELISA), second generation (Alere, Australia) (ii) the Panbio dengue virus IgM capture ELISA (Alere, Australia) (iii) the Panbio dengue virus IgG capture ELISA (Alere, Australia) (iv) the Standard Diagnostics dengue virus NS1 antigen ELISA (Standard Diagnostics, South Korea) (v) the Standard Diagnostics dengue virus IgM ELISA (Standard Diagnostics, South Korea) (vi) the Standard Diagnostics dengue virus IgG ELISA (Standard Diagnostics, South Korea) and (vii) the Platelia NS1 antigen ELISA (Bio-Rad, France). S les from 239 Thai patients confirmed to be dengue virus positive and 98 Sri Lankan patients negative for dengue virus infection were tested. The sensitivities and specificities of the NS1 antigen ELISAs ranged from 45 to 57% and 93 to 100% and those of the IgM antibody ELISAs ranged from 85 to 89% and 88 to 100%, respectively. Combining the NS1 antigen and IgM antibody results from the Standard Diagnostics ELISAs gave the best compromise between sensitivity and specificity (87 and 96%, respectively), as well as providing the best sensitivity for patients presenting at different times after fever onset. The Panbio IgG capture ELISA correctly classified 67% of secondary dengue infection cases. This study provides strong evidence of the value of combining dengue virus antigen- and antibody-based test results in the ELISA format for the diagnosis of acute dengue infection.
Publisher: Public Library of Science (PLoS)
Date: 13-09-2011
Publisher: Oxford University Press (OUP)
Date: 03-2007
Publisher: American Society of Tropical Medicine and Hygiene
Date: 06-05-2015
Publisher: Elsevier BV
Date: 11-1997
DOI: 10.1016/S0378-1135(97)00155-7
Abstract: In 1992, a virus (DPP2209) isolated from sentinel cattle located at Coastal Plains Research Station, latitude 12 degrees 39'S, longitude 131 degrees 20'E, approximately 60 km east of Darwin, Northern Territory. This virus was identified as a serotype of epizootic haemorrhagic disease (EHD) of deer virus previously undescribed in Australia. An additional 17 isolation of this virus were made from eight animals during the period February to May. Electron microscopic studies showed the presence of orbivirus-like structures. Serogrouping ELISA, indirect immunofluorescence assay and the serogrouping plaque reduction neutralisation test indicated the virus was a member of the epizootic haemorrhagic disease serogroup. Serotype specific plaque reduction neutralisation tests, indicated the virus was a member of the epizootic haemorrhagic disease serogroup not previously isolated in Australia. Analysis of the VP3 gene confirmed this observation. Cross neutralisation testing of the isolate with known epizootic haemorrhagic disease serotype viruses including endemic Australian and exotic strains identified isolate DPP2209 as epizootic haemorrhagic disease virus serotype 1.
Publisher: Elsevier BV
Date: 2008
DOI: 10.1016/J.DIAGMICROBIO.2007.07.011
Abstract: We evaluated 2 commercial enzyme-linked immunosorbent assays (ELISAs) for the diagnosis of dengue infection one a serologic test for immunoglobulin M (IgM) antibodies, the other based on detection of dengue virus nonstructural 1 (NS1) antigen. Using gold standard reference serology on paired sera, 41% (38/92 patients) were dengue confirmed, with 4 (11%) acute primary and 33 (87%) acute secondary infections (1 was of indeterminate status). Sensitivity of the NS1-ELISA was 63% (95% confidence interval [CI], 53-73) on admission s les but was much less sensitive (5% 95% CI, 1-10) on convalescent s les. The IgM capture ELISA had a lower but statistically equivalent sensitivity compared with the NS1-ELISA for admission s les (45% 95% CI, 35-55) but was more sensitive on convalescent s les (58% 95% CI, 48-68). The results of the NS1 and IgM capture ELISAs were combined using a logical OR operator, increasing the sensitivity for admission s les (79% 95% CI, 71-87), convalescent s les (63% 95% CI, 53-73), and all s les (71% 95% CI, 65-78).
Publisher: Elsevier BV
Date: 02-2021
Publisher: Cambridge University Press (CUP)
Date: 2019
DOI: 10.1017/S0950268819001390
Abstract: Spotted fever group rickettsiae (SFG) are a neglected group of bacteria, belonging to the genus Rickettsia , that represent a large number of new and emerging infectious diseases with a worldwide distribution. The diseases are zoonotic and are transmitted by arthropod vectors, mainly ticks, fleas and mites, to hosts such as wild animals. Domesticated animals and humans are accidental hosts. In Asia, local people in endemic areas as well as travellers to these regions are at high risk of infection. In this review we compare SFG molecular and serological diagnostic methods and discuss their limitations. While there is a large range of molecular diagnostics and serological assays, both approaches have limitations and a positive result is dependent on the timing of s le collection. There is an increasing need for less expensive and easy-to-use diagnostic tests. However, despite many tests being available, their lack of suitability for use in resource-limited regions is of concern, as many require technical expertise, expensive equipment and reagents. In addition, many existing diagnostic tests still require rigorous validation in the regions and populations where these tests may be used, in particular to establish coherent and worthwhile cut-offs. It is likely that the best strategy is to use a real-time quantitative polymerase chain reaction (qPCR) and immunofluorescence assay in tandem. If the specimen is collected early enough in the infection there will be no antibodies but there will be a greater chance of a PCR positive result. Conversely, when there are detectable antibodies it is less likely that there will be a positive PCR result. It is therefore extremely important that a complete medical history is provided especially the number of days of fever prior to s le collection. More effort is required to develop and validate SFG diagnostics and those of other rickettsial infections.
Publisher: Public Library of Science (PLoS)
Date: 20-11-2014
Publisher: Springer Science and Business Media LLC
Date: 14-02-2018
Publisher: Springer Science and Business Media LLC
Date: 15-04-2019
Publisher: Elsevier BV
Date: 09-1996
DOI: 10.1016/0378-1135(96)00020-X
Abstract: An antigen-capture ELISA (Ag-ELISA) was developed to detect bluetongue virus (BTV) antigen directly from blood s les. Four blood preparations [whole blood, buffy coat, washed red blood cells (RBC) and plasma] taken pre-inoculation and on days 6 to 9 post-inoculation (PI) were used in the ELISA to study antigenaemia in forty sheep, each experimentally infected with one of 20 South African BTV serotypes. Seventeen of the 20 serotypes were detected and 27 of the 40 sheep were at some stage Ag-ELISA positive. Over the period of s ling, Ag-ELISA positive results were most frequently returned from whole blood taken on days 6 and 7 PI. However in some instances the quantity and/or duration of BTV antigenaemia was greater in buffy coat and washed RBC preparations. In a selection of s les examined, positive Ag-ELISA results were generally obtained when s les had an infectious virus titre in eggs of > 10(3.2) egg lethal doses (ELD50/ml). The appearance and duration of detectable antigenaemia was compared with the development of clinical signs and antibody responses of infected sheep. On days 6 and 7 PI the presence of fever (> 40 degrees C) was indicative to the likelihood of detectable antigenaemia. After day 5 PI antigenaemia declined and clinical signs of swollen face and inflamed feet appeared together with the first detectable antibody response. The Ag-ELISA, when used in conjunction with clinical observations and serologic data, should be useful as a rapid diagnostic procedure for bluetongue disease.
Publisher: MDPI AG
Date: 18-05-2022
DOI: 10.3390/TROPICALMED7050078
Abstract: A national animal disease surveillance network initiated by the Lao PDR government is adopted and reinforced by a joint research project between the National Animal Health Laboratory (NAHL), the Department of Livestock and Fisheries (DLF), and the Mahidol Oxford Tropical Medicine Research Unit (MORU). The network is strengthened by staff training and practical exercises and is utilised to provide zoonotic or high-impact disease information on a national scale. Between January and December 2020, large ruminant s les are collected monthly from 18 abattoirs, one in each province, by provincial and district agriculture and forestry officers. The surveillance network collected a total of 4247 serum s les (1316 buffaloes and 2931 cattle) over this period. S les are tested for antibodies against Brucella spp., Coxiella burnetii (Q fever) and Foot-and-Mouth Disease Non-Structural Protein (FMD NSP) using commercial ELISA kits and the Rose Bengal test. Seroprevalences of Q fever and brucellosis in large ruminants are low at 1.7% (95% CI: 1.3, 2.1) and 0.7% (95% CI: 0.5, 1.0) respectively, while for FMD NSP it is 50.5% (95% CI: 49.0, 52.0). Univariate analyses show differences in seroprevalences of Q fever between destination (abattoir) province (p-value = 0.005), province of origin (p-value = 0.005), animal type (buffalo or cattle) (p-value = 0.0008), and collection month (p-value = 3.4 × 10−6). Similar to Q fever, seroprevalences of brucellosis were significantly different for destination province (p-value 0.00001), province of origin (p-value 0.00001), animal type (p-value = 9.9 × 10−5) and collection month (p-value 0.00001), plus body condition score (p-value = 0.003), and age (p-value = 0.007). Additionally, risk factors of the FMD NSP dataset include the destination province (p-value 0.00001), province of origin (p-value 0.00001), sex (p-value = 7.97 × 10−8), age (p-value = 0.009), collection date (p-value 0.00001), and collection month (p-value 0.00001). Spatial analyses revealed that there is no spatial correlation of FMD NSP seropositive animals. High-risk areas for Q fever and brucellosis are identified by spatial analyses. Further investigation of the higher risk areas would provide a better epidemiological understanding of both diseases in Lao PDR. In conclusion, the abattoir serological survey provides useful information about disease exposure and potential risk factors. The network is a good base for field and laboratory staff training in practical technical skills. However, the sustainability of such a surveillance activity is relatively low without an external source of funding, given the operational costs and insufficient government budget. The cost-effectiveness of the abattoir survey could be increased by targeting hotspot areas, reducing fixed costs, and extending the focus to cover more diseases.
Publisher: American Physiological Society
Date: 04-2016
DOI: 10.1152/JAPPLPHYSIOL.00820.2015
Abstract: The mechanisms leading to upper airway (UA) collapse during sleep are complex and poorly understood. We previously developed an anesthetized rabbit model for studying UA physiology. On the basis of this body of physiological data, we aimed to develop and validate a two-dimensional (2D) computational finite element model (FEM) of the passive rabbit UA and peripharyngeal tissues. Model geometry was reconstructed from a midsagittal computed tomographic image of a representative New Zealand White rabbit, which included major soft (tongue, soft palate, constrictor muscles), cartilaginous (epiglottis, thyroid cartilage), and bony pharyngeal tissues (mandible, hard palate, hyoid bone). Other UA muscles were modeled as linear elastic connections. Initial boundary and contact definitions were defined from anatomy and material properties derived from the literature. Model parameters were optimized to physiological data sets associated with mandibular advancement (MA) and caudal tracheal displacement (TD), including hyoid displacement, which featured with both applied loads. The model was then validated against independent data sets involving combined MA and TD. Model outputs included UA lumen geometry, peripharyngeal tissue displacement, and stress and strain distributions. Simulated MA and TD resulted in UA enlargement and nonuniform increases in tissue displacement, and stress and strain. Model predictions closely agreed with experimental data for in idually applied MA, TD, and their combination. We have developed and validated an FEM of the rabbit UA that predicts UA geometry and peripharyngeal tissue mechanical changes associated with interventions known to improve UA patency. The model has the potential to advance our understanding of UA physiology and peripharyngeal tissue mechanics.
Publisher: Public Library of Science (PLoS)
Date: 23-03-2022
DOI: 10.1371/JOURNAL.PNTD.0010256
Abstract: In this study, we estimated exposure for Scrub typhus (STG), Typhus (TG) and Spotted fever groups (SFG) rickettsia using serology at a fine scale (a whole sub-district administration level) of local communities in Nan Province, Thailand. Geographical characteristics of the sub-district were ided into two landscape types: lowland agricultural area in an urbanized setting (lowland-urbanized area) and upland agricultural area located close to a protected area of National Park (upland-forested area). This provided an ideal contrast between the two landscapes with low and high levels of human-altered habitats to study in differences in disease ecology. In total, 824 serum s les of participants residing in the eight villages were tested by screening IgG ELISA, and subsequently confirmed by the gold standard IgG Immunofluorescent Assay (IFA). STG and TG IgG positivity were highest with seroprevalence of 9.8% and 9.0%, respectively whereas SFG positivity was lower at 6.9%. Inhabitants from the villages located in upland-forested area demonstrated significantly higher STG exposure, compared to those villages in the lowland-urbanized area (chi-square = 51.97, p 0.0001). In contrast, TG exposure was significantly higher in those villagers living in lowland-urbanized area (chi-square = 28.26, p 0.0001). In addition to the effect of landscape types, generalized linear model (GLM) analysis identified socio-demographic parameters, i.e., gender, occupation, age, educational level, domestic animal ownership (dog, cattle and poultry) as influential factors to explain the level of rickettsial exposure (antibody titers) in the communities. Our findings raise the public health awareness of rickettsiosis as a cause of undiagnosed febrile illness in the communities.
Publisher: Springer Science and Business Media LLC
Date: 12-2019
DOI: 10.1186/S12879-019-4653-4
Abstract: Scrub typhus is an important arthropod-borne disease causing significant acute febrile illness by infection with Orientia spp . Using a risk-based approach, this review examines current practice, the evidence base and regulatory requirements regarding matters of biosafety and biosecurity, and presents the case for reclassification from Risk Group 3 to Risk Group 2 along with recommendations for safe working practices of risk-based activities during the manipulation of Orientia spp. in the laboratory. We recommend to reclassify Orientia spp. to Risk Group 2 based on the classification for RG2 pathogens as being moderate in idual risk, low community risk. We recommend that low risk activities, can be performed within a biological safety cabinet located in a Biosafety Level (BSL) 2 core laboratory using standard personal protective equipment. But when the risk assessment indicates, such as high concentration and volume, or aerosol generation, then a higher biocontainment level is warranted. For, the majority of animal activities involving Orientia spp., Animal BSL 2 (ABSL2) is recommended however where high risk activities are performed including necropsies, Animal BSL (ABSL3) is recommended.
Publisher: Springer Science and Business Media LLC
Date: 08-2006
DOI: 10.1007/S11250-006-4434-0
Abstract: This study investigated the comparative susceptibility of indigenous Moo Laat and improved Large White/Landrace pig breeds to infection with classical swine fever virus (CSFV) under controlled conditions in the Lao People's Democratic Republic (Lao PDR). The Moo Laat (ML) and Large White/Landrace cross-breed (LWC) pigs were inoculated with a standard challenge strain designated Lao/Kham225 (infectivity titre of 10(2.75) TCID50/ml). The results demonstrated that both the native breed and an improved pig breed are fully susceptible to CSFV infection and the mortality rate is high. LWC pigs demonstrated lower (or shorter) survival times (50% survival time: 11 days), earlier and higher pyrexia and earlier onset of viraemia compared to ML pigs (50% survival time: 18 days). In the context of village-based pig production, the longer time from infection to death in native ML pigs means that incubating or early sick pigs are likely to be sold once an outbreak of CSF is recognized in a village. This increased longevity probably contributes to the maintenance and spread of disease in a population where generally the contact rate is low.
Publisher: MDPI AG
Date: 18-05-2022
DOI: 10.3390/TROPICALMED7050077
Abstract: Rickettsial infections are among the leading etiologies of acute febrile illness in Southeast Asia. However, recent data from Malaysia are limited. This prospective study was conducted in Teluk Intan, Peninsular Malaysia, during January to December 2016. We recruited 309 hospitalized adult patients with acute febrile illness. Clinical and biochemistry data were obtained, and patients were stratified into mild and severe infections based on the sepsis-related organ failure (qSOFA) scoring system. Diagnostic assays including blood cultures, real-time PCR, and serology (IFA and MAT) were performed. In this study, pathogens were identified in 214 (69%) patients, of which 199 (93%) patients had a single etiology, and 15 (5%) patients had etiologies. The top three causes of febrile illness requiring hospitalization in this Malaysian study were leptospirosis (68 (32%)), dengue (58 (27%)), and rickettsioses (42 (19%)). Fifty-five (18%) patients presented with severe disease with a qSOFA score of ≥2. Mortality was documented in 38 (12%) patients, with the highest seen in leptospirosis (16 (42%)) followed by rickettsiosis (4 (11%)). While the significance of leptospirosis and dengue are recognized, the impact of rickettsial infections in Peninsular Malaysia remains under appreciated. Management guidelines for in-patient care with acute febrile illness in Peninsular Malaysia are needed.
Publisher: Elsevier BV
Date: 04-2001
Publisher: Springer Science and Business Media LLC
Date: 02-03-2015
Publisher: American Society of Tropical Medicine and Hygiene
Date: 04-2015
Publisher: MDPI AG
Date: 26-03-2018
Publisher: Mary Ann Liebert Inc
Date: 12-2019
Publisher: American Society of Tropical Medicine and Hygiene
Date: 15-11-2016
Publisher: Springer Science and Business Media LLC
Date: 11-11-2015
Publisher: Public Library of Science (PLoS)
Date: 30-03-2016
Publisher: Oxford University Press (OUP)
Date: 15-04-2006
DOI: 10.1086/501358
Abstract: The serological diagnosis of acute dengue virus infection relies on the detection of dengue-specific immunoglobulin M (IgM) antibodies. Immunochromatographic tests are rapid diagnostic tests (RDTs) that can be performed at the bedside, but they have not been fully validated for diagnosis of dengue infection. More than 20 RDTs for diagnosis of acute dengue infection are commercially available. Of these, 8 were selected for evaluation of performance by use of characterized dengue and nondengue serum specimens, and results were compared with those of a previously published dengue IgM/IgG enzyme-linked immunosorbent assay in conjunction with dengue virus serotyping by reverse-transcriptase polymerase chain reaction. Assay sensitivities were low, ranging from 6.4% (95% confidence interval [CI], 4.0%-9.7%) to 65.3% (95% CI, 59.9%-70.5%), and specificities ranged from 69.1% (95% CI, 61.4%-76.0%) to 100% (95% CI, 97.8%-100%). Of the 8 tests, only 2 had sensitivities of >50%, the level considered to be clinically useful, and, of these, 1 had relatively low specificity (69.1%). S les collected early in the infection were less likely to test positive than those collected later. A thermal stability study demonstrated a loss in performance of some RDTs when they were stored at a high ambient temperature for 3 months. Users of RDTs for dengue should be aware that many of these tests have a diagnostic accuracy that falls well below the manufacturers' claims. If an acute specimen yields a negative result, a convalescent serum s le should be tested to confirm the result. No RDT adequately differentiated primary and secondary dengue infections, and the tests should not be used for this purpose.
Publisher: Centers for Disease Control and Prevention (CDC)
Date: 04-2018
Publisher: Oxford University Press (OUP)
Date: 10-08-2019
DOI: 10.1093/CID/CIY675
Abstract: The highest-risk activities for scrub/murine typhus laboratory-acquired infections were working with infectious laboratory animals. Eight scrub typhus deaths occurred during the preantibiotic era. Risk-based biosafety approaches would improve efficiencies of in vitro/in vivo growth of scrub/murine typhus.
Publisher: Oxford University Press (OUP)
Date: 04-2008
Publisher: MDPI AG
Date: 23-12-2022
DOI: 10.3390/TROPICALMED8010010
Abstract: Scrub typhus is a mite-borne disease caused by a Gram-negative obligately intracellular bacillus, Orientia tsutsugamushi. The disease is endemic in the Asia–Australia–Pacific region, including Thailand. Scrub typhus generally manifests as acute undifferentiated febrile fever along with myalgia, rash, and lymphadenopathy. An eschar can be a valuable diagnostic clue, but this skin lesion may be missed in some patients. The disease symptoms resemble those of other febrile illnesses such as leptospirosis, typhoid, murine typhus, malaria, and dengue fever, making a laboratory diagnosis necessary for the definitive diagnosis. In this study, we expressed a recombinant protein derived from 56-kDa type-specific antigen of O. tsutsugamushi Karp serotype and tested its ability to detect and differentiate scrub typhus infection. IgM and IgG antibodies were determined in sera from scrub typhus (n = 92) and other febrile illness patients (murine typhus (n = 25), melioidosis (n = 36), leptospirosis (n = 42), and dengue (n = 35)) from Thailand. Sensitivities of 87.0% and 59.8% with a specified assay cut-off were obtained for IgM and IgG indirect ELISAs, respectively, with a specificity of 100% in both tests. The sensitivity was increased to 95.7% when a combination of IgM and IgG ELISAs results was considered. Our study suggested a potential of the 56-kDa recombinant protein for further development and evaluation for use in scrub typhus serodiagnosis.
Publisher: Elsevier BV
Date: 07-2013
Publisher: American Society for Microbiology
Date: 11-2015
DOI: 10.1128/JCM.01680-15
Abstract: We determined the optimal cutoff titers in admission and convalescent-phase s les for scrub typhus indirect immunofluorescence assay using Bayesian latent class models. Cutoff titers of ≥1:3,200 in an admission s le or of a ≥4-fold rise to ≥1:3,200 in a convalescent-phase s le provided the highest accuracy (sensitivity, 81.6% specificity, 100%).
Publisher: Public Library of Science (PLoS)
Date: 09-03-2018
Publisher: Public Library of Science (PLoS)
Date: 31-07-2014
Publisher: American Society for Microbiology
Date: 11-2007
DOI: 10.1128/CVI.00482-06
Abstract: There is an urgent need for accurate and simple dengue virus infection diagnostic assays in limited-resource settings of dengue endemicity, to assist patient management. Using a panel of reference s les (S. D. Blacksell, P. N. Newton, D. Bell, J. Kelley, M. P. Mammen, D. W. Vaughn, V. Wuthiekanun, A. Sungkakum, A. Nisalak, and N. P. Day, Clin. Infect. Dis. 42:1127-1134, 2006), we recently evaluated eihgt commercially available immunochromatographic rapid diagnostic tests (RDTs) designed to detect dengue virus-specific immunoglobulin M (IgM) and/or IgG. We found that 6/8 RDTs had sensitivities of less than 50% (range, 6 to 65%), but specificities were generally high. Here, in conjuction with dengue virus serotyping by reverse transcriptase PCR and in the limited-resource setting of Laos, where dengue virus is endemic, we evaluated the same eight RDTs against a previously validated dengue IgM/IgG enzyme-linked immunosorbent assay for diagnosis of acute dengue virus infection. Paired serum s les were collected from 87 patients, of whom 38 had confirmed dengue virus infections (4 had primary infections, 33 had secondary infections, and 1 had an infection of indeterminate status). RDT sensitivity was low, with 7/8 RDTs having admission s le sensitivities of less than 20% (range, 4 to 26%). The majority (6/8) of the RDTs, demonstrated high specificity ( %). Kappa statistic values ranged from 6 to 54% for the RDTs, demonstrating poor to moderate variation between three operators. No RDT adequately differentiated between primary and secondary dengue virus infections. The findings of this study suggest that currently available RDTs based on the detection of IgM antibodies for the diagnosis of acute dengue virus infections are unlikely to be useful for patient management.
Publisher: Springer Science and Business Media LLC
Date: 12-2005
DOI: 10.1007/S11262-005-3253-0
Abstract: The 5' non-coding region (5'-NCR) of 27 classical swine fever virus (CSFV) isolates from Lao People's Democratic Republic (Lao PDR) during 1997 and 1999 were lified by RT-PCR. A 150-bp region of the 5'-NCR licons was analysed and compared with reference CSFV of European and Asian origin and a phylogenetic dendrogram constructed. Following analysis, all viruses were determined to belong to genogroup 2. Viruses from Lao PDR grouped on a geographical basis with the majority of northern/central isolates falling into subgroup 2.1 and southern/central isolates falling into subgroup 2.2. These results concur with previous studies of CSF viruses from Lao PDR, although this study recognized the first occurrence of subgroup 2.1 in southern Lao PDR.
Publisher: Mary Ann Liebert Inc
Date: 06-2013
Publisher: Oxford University Press (OUP)
Date: 02-2007
DOI: 10.1086/510585
Abstract: A review was performed to determine the evidence base for scrub typhus indirect immunofluorescence assay (IFA) methodologies and the criteria for positive results. This review included a total of 109 publications, which comprised 123 eligible studies for analysis (14 publications included 2 substudies). There was considerable underreporting of the IFA methodology and seropositivity criteria used, with most studies using a defined cutoff titer rather than an increase in the titer in paired s les. The choice of positivity cutoff titer varied by country and purpose of the IFA test. This variation limits the comparability of seroprevalence rates between studies and, more seriously, raises questions about the appropriateness of the cutoffs for positive IFA results chosen for diagnosis of acute scrub typhus infection. We suggest that the diagnosis of scrub typhus using IFA should be based on a > or =4-fold increase in the titer in paired serum s les and should only be based on a single s le titer when there is an adequate local evidence base.
Publisher: Oxford University Press (OUP)
Date: 06-2005
DOI: 10.1016/J.TRSTMH.2004.08.007
Abstract: We conducted a randomized open trial of oral chlor henicol (50mg/kg/day in four ided doses for 14 days) versus ofloxacin (15 mg/kg/day in two ided doses for 3 days) in 50 adults with culture-confirmed uncomplicated typhoid fever in Vientiane, Laos. Patients had been ill for a median (range) of 8 (2-30) days. All Salmonella enterica serotype typhi isolates were nalidixic acid-sensitive, four (8%) were chlor henicol-resistant and three (6%) were multidrug-resistant. Median (range) fever clearance times were 90 (24-224) hours in the chlor henicol group and 54 (6-93) hours in the ofloxacin group (P<0.001). One patient in the chlor henicol group developed an ileal perforation. Three days ofloxacin was more effective than 14 days chlor henicol for the in-patient treatment of typhoid fever, irrespective of antibiotic susceptibility, and was of similar cost.
Publisher: Oxford University Press (OUP)
Date: 07-2007
DOI: 10.1016/J.TRSTMH.2007.02.015
Abstract: Serological testing of paired (i.e. admission and convalescent) sera from 103 fever patients in Kathmandu, Nepal, was performed to estimate the prevalence rates of scrub typhus, murine typhus, Leptospira and dengue virus antibodies and to determine their role in the cause of active infections. Blood cultures from 15 patients grew Salmonella enterica serovar Typhi, 8 grew S. Paratyphi A and 6 grew other bacteria. Diagnostic antibody levels were detected against murine typhus (27/103 26%), scrub typhus (23/103 22%), Leptospira (10/103 10%) and dengue virus (8/103 8%). Nineteen patients (18%) had diagnostically raised antibodies to more than one infectious agent. Seven S. Typhi (7/15 47%) and two S. Paratyphi A (2/8 25%) patients had significant scrub typhus, murine typhus, Leptospira or dengue virus IgM antibody titres. This study confirms the presence of leptospiral, rickettsial and dengue infections in Kathmandu as well as evidence for mixed infections with S. Typhi and Orientia tsutsugamushi or Rickettsia typhi. These infections should be kept in mind when considering the differential diagnoses of fever and empirical treatment options in Nepal. Many patients demonstrated static IgM antibody results between paired serum collections, suggesting recent rather than acutely active infections.
Publisher: Elsevier BV
Date: 03-2021
Publisher: Elsevier BV
Date: 09-2009
Abstract: It is well understood that sociocultural practices strongly influence Taenia solium transmission however, the extent to which interspecific parasite competition moderates Taenia transmission has yet to be determined. This is certainly the case in Southeast Asia where T. solium faces competition in both the definitive host (people) and the intermediate host (pigs). In people, adult worms of T. solium, T. saginata and T. asiatica compete through density-dependent crowding mechanisms. In pigs, metacestodes of T. solium, T. hydatigena and T. asiatica compete through density-dependent immune-mediated interactions. Here, we describe the biological and epidemiological implications of Taenia competition and propose that interspecific competition has a moderating effect on the transmission dynamics of T. solium in the region. Furthermore, we argue that this competitive ecological scenario should be considered in future research and surveillance activities examining T. solium cysticercosis and taeniasis in Southeast Asia.
Publisher: Public Library of Science (PLoS)
Date: 28-08-2015
Publisher: Elsevier BV
Date: 06-1994
DOI: 10.1016/0166-0934(94)90088-4
Abstract: The humoral immune response of sheep infected with bluetongue virus serotypes 3, 9 and 16 was monitored by plaque inhibition (PI), blocking ELISA (BELISA) and indirect ELISA over a period of 63 days post-infection. Results indicated that testing of a single plasma or serum s le by both a BELISA and an indirect ELISA using a recombinant streptococcal protein G (PrG) peroxidase conjugate enabled an assessment of the proximity of a recent infection based on the failure of PrG to bind ovine IgM class antibodies. When BELISA and indirect ELISA results were expressed as a ratio, values indicative of recent infection (> or = 5) were observed for an average duration of 16.5 days (range 8 to 23 days) following the initial detection of antibody by BELISA. This approach has potential to improve diagnosis of a wide range of virus infections by providing an indicator for the relationship of serological status with a recent infection. However, where reinfection may occur, as with bluetongue virus, alternative methods may be required for definitive diagnosis.
Publisher: Mary Ann Liebert Inc
Date: 10-2012
Abstract: Bovine-associated zoonotic infectious diseases pose a significant threat to human health in the Lao People's Democratic Republic (Lao PDR). In all, 905 cattle and buffalo serum s les collected in northern Lao PDR in 2006 were used to determine seroprevalence of five major bovine zoonotic infectious diseases that included Taenia saginata cysticercosis, bovine tuberculosis, Q-fever, bovine brucellosis, and bovine leptospirosis. Five enzyme-linked immunosorbent assays (ELISAs) were used to test for the presence of antibodies to the diseases, except Taenia saginata, for which we tested for the presence of Taenia metacestode circulating antigens. The overall highest prevalence was for T. saginata (46.4%), with lower prevalence for Q-fever (4%), leptospirosis (3%), tuberculosis (1%), and brucellosis (0.2%). Although there were no significant differences in the proportion of seroprevalence between sex and age of the animals s led, there were significant differences between the provincial distributions. Further studies are required to determine the seroprevalence of these infections in other locations in Lao PDR, as well as other animal species including humans, in order to develop effective prevention and control strategies. This is the first study to investigate the prevalence of bovine zoonotic infectious agents in the Lao PDR. Positivity was demonstrated for all diseases investigated, with the highest prevalence for T. saginata antigen and Coxiella burnetti antibodies. For T. saginata, there were significant differences in the provincial distribution. Approximately 16% seroprevalence of Coxiella burnetti was noted in Xayabuly Province however, there are no clear reasons why this was the case, and further studies are required to determine risk factors associated with this observation.
Publisher: Springer Science and Business Media LLC
Date: 2007
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.PREVETMED.2018.11.012
Abstract: Pigs in Lao People's Democratic Republic are important for income and food security, particularly in rural households. The majority of pigs are reared in smallholder systems, which may challenge the implementation of any disease control strategies. To investigate risk factors for pig production diseases in such farming systems in the country a serological survey was conducted during 2011. A total of 647 pigs were s led, accounting for 294 households in Luang Prabang and 353 in Savannakhet province representing upland and lowland, respectively. The results demonstrated that pigs in Lao PDR had antibodies against erysipelas (45.2%), CSF (11.2%), PRRS (8.6%), FMD O (17.2%) and FMD Asia 1, (3.5%). Differences in the housing systems influenced disease risk, for ex le, penned pigs had reduced odds of FMD and CSF, compared to those in scavenger systems. Pigs owned by farms using a sanaam (a communal area where pigs are kept for some time of the year) had 3.93 (95% confidence interval (CI): 1.09-14.7) times the odds of having pigs seropositive for FMD. Farms on which sudden piglet deaths had been experienced were more likely to have pigs seropositive for FMD O and erysipelas. These diseases constrain the development of village farming and the wider livestock industry due to their impact on productivity and trade. Vaccination coverage for FMD and CSF was low and there was a lack of national funding for livestock disease control at the time of the study. Further investigation into sustainable low-cost control strategies for these pathogens is warranted.
Publisher: American Physiological Society
Date: 11-2019
DOI: 10.1152/JAPPLPHYSIOL.00660.2018
Abstract: Tracheal displacement is thought to be the primary mechanism by which changes in lung volume influence upper airway patency. Caudal tracheal displacement during inspiration may help preserve the integrity of the upper airway in response to increasing negative airway pressure by stretching and stiffening pharyngeal tissues. However, tracheal displacement has not been previously quantified in obstructive sleep apnea (OSA). Accordingly, we aimed to measure tracheal displacements in awake in iduals with and without OSA. The upper head and neck of 34 participants [apnea-hypopnea index (AHI) = 2–74 events/h] were imaged in the midsagittal plane using dynamic magnetic resonance imaging (MRI) during supine awake quiet breathing. MRI data were analyzed to identify peak tracheal displacement and its timing relative to inspiration. Epiglottic pressure was measured separately for a subset of participants ( n = 30) during similar experimental conditions. Nadir epiglottic pressure and its timing relative to inspiration were quantified. Peak tracheal displacement ranged from 1.0–9.6 mm, with a median (25th–75th percentile) of 2.3 (1.7–3.5) mm, and occurred at 89 (78–99)% of inspiratory time. Peak tracheal displacement increased with increasing OSA severity (AHI) ( R 2 = 0.28, P = 0.013) and increasing negative nadir epiglottic pressure ( R 2 = 0.47, P = 0.023). Relative inspiratory timing of peak tracheal displacement also correlated with OSA severity, with peak displacement occurring earlier in inspiration with increasing AHI ( R 2 = 0.36, P = 0.002). Tracheal displacements during quiet breathing are larger in in iduals with more severe OSA and tend to reach peak displacement earlier in the inspiratory cycle. Increased tracheal displacement may contribute to maintenance of upper airway patency during wakefulness in OSA, particularly in those with severe disease. NEW & NOTEWORTHY Tracheal displacement is thought to play an important role in stabilizing the upper airway by stretching/stiffening the pharyngeal musculature. Using dynamic magnetic resonance imaging, this study shows that caudal tracheal displacement is more pronounced during inspiration in obstructive sleep apnea (OSA) compared with healthy in iduals. Softer pharyngeal muscles and greater inspiratory forces in OSA may underpin greater tracheal excursion. These findings suggest that tracheal displacement may contribute to maintenance of pharyngeal patency during wakefulness in OSA.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 03-09-2014
Publisher: American Society for Microbiology
Date: 03-2012
DOI: 10.1128/CVI.05478-11
Abstract: S les from 160 prospectively recruited febrile patients with typhus-like illness in an area of Thailand (Chiang Rai, northern Thailand) where scrub typhus is endemic were used to evaluate the diagnostic capabilities of four rapid immunochromatographic tests (ICTs) for the detection of Orientia tsutsugamushi IgM and total antibodies during acute scrub typhus infection. Of the 160 cases, 54 (34%) had been confirmed to have scrub typhus using the reference scrub typhus infection criteria (STIC), i.e., positive cell culture isolation, an admission IgM antibody titer of ≥1:12,800, a 4-fold rising IgM antibody titer, and/or positivity for ≥2 out of 3 PCR gene targets). The ICTs gave the following sensitivities and specificities: the Panbio IgM ICT, 46% (95% confidence interval [CI], 33 to 60) and 95% (95% CI, 89 to 98), respectively the Standard Diagnostics IgM ICT, 68% (95% CI, 60 to 75) and 73% (95% CI, 68 to 78), respectively the AccessBio IgM ICT, 56% (95% CI, 48 to 63) and 90% (95% CI, 87 to 94), respectively and the AccessBio total antibody ABt ICT, 61% (95% CI, 53 to 68) and 68% (95% CI, 63 to 73), respectively. An isothermal loop lification (LAMP) PCR assay for scrub typhus demonstrated a sensitivity of 52% (95% CI, 38 to 66) and a specificity of 94% (95% CI, 88 to 98). This study has revealed the diagnostic limitations of antibody-based assays in an acute care setting. However, the combination of ICTs with LAMP usually increased sensitivity with a minimal reduction in specificity. The best combination, the Panbio IgM ICT and LAMP, resulted in a sensitivity of 67% (95% CI, 53 to 79) and a specificity of 91% (95% CI, 83 to 95). The combination of antibody-based assays with DNA- or antigen-based tests shows promise for improved diagnostic sensitivity.
Publisher: Public Library of Science (PLoS)
Date: 26-03-2018
Publisher: The American Association of Immunologists
Date: 15-02-2015
Abstract: We developed an intradermal (ID) challenge cynomolgus macaque (Macaca fascicularis) model of scrub typhus, the leading cause of treatable undifferentiated febrile illness in tropical Asia, caused by the obligate intracellular bacterium, Orientia tsutsugamushi. A well-characterized animal model is required for the development of clinically relevant diagnostic assays and evaluation of therapeutic agents and candidate vaccines. We investigated scrub typhus disease pathophysiology and evaluated two O. tsutsugamushi 47-kDa, Ag-based candidate vaccines, a DNA plasmid vaccine (pKarp47), and a virus-vectored vaccine (Kp47/47-Venezuelan equine encephalitis virus replicon particle) for safety, immunogenicity, and efficacy against homologous ID challenge with O. tsutsugamushi Karp. Control cynomolgus macaques developed fever, classic eschars, lymphadenopathy, bacteremia, altered liver function, increased WBC counts, pathogen-specific Ab (IgM and IgG), and cell-mediated immune responses. Vaccinated macaques receiving the DNA plasmid pKarp47 vaccine had significantly increased O. tsutsugamushi–specific, IFN-γ–producing PBMCs (p = 0.04), reduced eschar frequency and bacteremia duration (p ≤ 0.01), delayed bacteremia onset (p & 0.05), reduced circulating bacterial biomass (p = 0.01), and greater reduction of liver transaminase levels (p & 0.03) than controls. This study demonstrates a vaccine-induced immune response capable of conferring sterile immunity against high-dose homologous ID challenge of O. tsutsugamushi in a nonhuman primate model, and it provides insight into cell-mediated immune control of O. tsutsugamushi and dissemination dynamics, highlights the importance of bacteremia indices for evaluation of both natural and vaccine-induced immune responses, and importantly, to our knowledge, has determined the first phenotypic correlates of immune protection in scrub typhus. We conclude that this model is suitable for detailed investigations into vaccine-induced immune responses and correlates of immunity for scrub typhus.
Publisher: Public Library of Science (PLoS)
Date: 18-01-2013
Publisher: American Society of Tropical Medicine and Hygiene
Date: 07-08-2013
Publisher: American Society of Tropical Medicine and Hygiene
Date: 05-2013
Publisher: Wiley
Date: 02-02-2021
Publisher: Cambridge University Press (CUP)
Date: 2023
DOI: 10.1017/S095026882300016X
Abstract: National disease surveillance systems are essential to a healthy pig industry but can be costly and logistically complex. In 2019, Lao People's Democratic Republic (Lao PDR) piloted an abattoir disease surveillance system to assess for the presence of high impact pig diseases (HIPDs) using serological methods. The Lao Department of Livestock and Fisheries (DLF) identified Classical Swine Fever (CSF), Porcine Respiratory and Reproductive Syndrome (PRRS) and Brucella suis as HIPDs of interest for sero-surveillance purposes. Porcine serum s les ( n = 597) were collected from six Lao abattoirs in March to December of 2019. Serological enzyme-linked immunosorbent assay (ELISA) methods were chosen for their high-throughput and relatively low-costs. The true seroprevalence for CSF and PRRS seropositivity were 68.7%, 95% CI (64.8–72.3) and 39.5%, 95% CI (35.7–43.5), respectively. The results demonstrated no evidence of Brucella spp. seroconversion. Lao breed pigs were less likely to be CSF seropositive ( P 0.05), whilst pigs slaughtered at year of age were less likely to be PRRS seropositive ( P 0.01). The testing methods could not differentiate between seropositivity gained from vaccine or natural infection, and investigators were unable to obtain the vaccine status of the slaughtered pigs from the abattoirs. These results demonstrate that adequate s le sizes are possible from abattoir sero-surveillance and lifetime health traceability is necessary to understand HIPDs in Lao PDR.
Publisher: Public Library of Science (PLoS)
Date: 20-07-2010
Publisher: Public Library of Science (PLoS)
Date: 25-08-0009
DOI: 10.1371/JOURNAL.PNTD.0009685
Abstract: Scrub typhus (ST) and murine typhus (MT) are common but poorly understood causes of fever in Laos. We examined the spatial and temporal distribution of ST and MT, with the intent of informing interventions to prevent and control both diseases. This study included s les submitted from 2003 to 2017 to Mahosot Hospital, Vientiane, for ST and MT investigation. Serum s les were tested using IgM rapid diagnostic tests. Patient demographic data along with meteorological and environmental data from Laos were analysed. Approximately 17% of patients were positive for either ST (1,337/8,150 patients tested) or MT (1,283/7,552 patients tested). While both diseases occurred in inhabitants from Vientiane Capital, from the univariable analysis MT was positively and ST negatively associated with residence in Vientiane Capital. ST was highly seasonal, with cases two times more likely to occur during the wet season months of July-September compared to the dry season whilst MT peaked in the dry season. Multivariable regression analysis linked ST incidence to fluctuations in relative humidity whereas MT was linked to variation in temperature. Patients with ST infection were more likely to come from villages with higher levels of surface flooding and vegetation in the 16 days leading up to diagnosis. The data suggest that as cities expand, high risk areas for MT will also expand. With global heating and risks of attendant higher precipitation, these data suggest that the incidence and spatial distribution of both MT and ST will increase.
Publisher: Mary Ann Liebert Inc
Date: 05-2015
Publisher: Elsevier BV
Date: 05-2022
Publisher: American Society of Tropical Medicine and Hygiene
Date: 03-2010
Publisher: Centers for Disease Control and Prevention (CDC)
Date: 09-2008
Publisher: American Society of Tropical Medicine and Hygiene
Date: 04-11-2015
Publisher: Mary Ann Liebert Inc
Date: 09-2016
Publisher: Wiley
Date: 06-09-2020
DOI: 10.1111/OIK.07332
Publisher: American Society for Microbiology
Date: 10-2006
DOI: 10.1128/CVI.00219-06
Abstract: The diagnostic utility of immunochromatographic (Leptotek) and enzyme-linked immunosorbent assay (ELISA Panbio) tests for the detection of Leptospira immunoglobulin M antibodies was assessed in febrile adults admitted in Vientiane, Laos. Both tests demonstrated poor diagnostic accuracy using admission serum (Leptotek sensitivity of 47.3% and specificity of 75.5%: ELISA sensitivity of 60.9% and specificity of 65.6%) compared to the Leptospira “gold standard” microscopic agglutination test.
Publisher: American Chemical Society (ACS)
Date: 22-07-2021
Publisher: American Physiological Society
Date: 02-2014
DOI: 10.1152/JAPPLPHYSIOL.00668.2014
Abstract: Mandibular advancement (MA) increases upper airway (UA) patency and decreases collapsibility. Furthermore, MA displaces the hyoid bone in a cranial-anterior direction, which may contribute to MA-associated UA improvements via redistribution of peripharyngeal tissue stresses (extraluminal tissue pressure, ETP). In the present study, we examined effects of MA on ETP distributions, deformation of the peripharyngeal tissue surface (UA geometry), and hyoid bone position. We studied 13 supine, anesthetized, tracheostomized, spontaneously breathing adult male New Zealand White rabbits. Graded MA was applied from 0 to ∼4.5 mm. ETP was measured at six locations distributed throughout three UA regions: tongue, hyoid, and epiglottis. Axial computed tomography images of the UA (nasal choanae to glottis) were acquired and used to measure lumen geometry (UA length regional cross-sectional area) and hyoid displacement. MA resulted in nonuniform decreases in ETP (greatest at tongue region), ranging from −0.11 (−0.15 to −0.06) to −0.82 (−1.09 to −0.54) cmH 2 O/mm MA [linear mixed-effects model slope (95% confidence interval)], across all sites. UA length decreased by −0.5 (−0.8 to −0.2) %/mm accompanied by nonuniform increases in cross-sectional area (greatest at hyoid region) ranging from 7.5 (3.6–11.4) to 18.7 (14.9–22.5) %/mm. The hyoid bone was displaced in a cranial-anterior direction by 0.42 (0.36–0.44) mm/mm MA. In summary, MA results in nonuniform changes in peripharyngeal tissue pressure distributions and lumen geometry. Displacement of the hyoid bone with MA may play a pivotal role in redistributing applied MA loads, thus modifying tissue stress/deformation distributions and determining resultant UA geometry outcomes.
Publisher: Elsevier BV
Date: 07-1996
DOI: 10.1016/0378-1135(95)00204-9
Abstract: Quality control (QC) procedures for antigen detection enzyme-linked immunosorbent assays (ELISAs) for hog cholera (HC) virus, foot and mouth disease (FMD) virus, and an antibody detection ELISA for FMD virus were established at a regional veterinary laboratory in northern Thailand. A recently developed computer software package, QCEL, was used to facilitate management and analysis of QC data. The program was used to assess test performance by producing Shewhart-CUSUM control charts which monitored control data for unacceptable fluctuations or trends. QCEL-generated control charts and analyses are presented and discussed. The use of a simple integrated computerised system for storage and analysis of QC control data provided the laboratory with the opportunity to achieve increased confidence in the results of tests performed.
Publisher: Public Library of Science (PLoS)
Date: 03-04-2023
DOI: 10.1371/JOURNAL.PNTD.0011244
Abstract: In Cambodia, goat production and meat consumption are customary among Muslim communities. Recently, goat meat has gained popularity among Cambodians. Goat farmers use a traditional management system, including grazing, requiring minimal labour. The close proximity between humans and animals could increase the risk of zoonotic disease transmission. A serological survey was undertaken to estimate the prevalence of some priority zoonoses and high-impact animal diseases in the Cambodian goat population. A total of 540 s les were collected from goats in six provinces and analysed with commercially available enzyme-linked immunosorbent assays for Brucella species, Q fever (C oxiella burnetii ), Foot and Mouth Disease virus non-structural protein (FMDV NSP) and Peste des Petits Ruminants virus (PPRV). True seroprevalences with a 95% Confidence Interval (CI), taking into account imperfect tests, risk factors and odds ratios (ORs), were calculated to better understand the disease distribution and epidemiology. Independent variables used in statistical modellings included sex, body condition score, age, vaccination history, province and commune, while dependent variables were ELISA test results. The overall true prevalence of antibodies to Brucella spp ., C . burnetii , FMDV and PPRV, were 0.1% (95% CI 0.0, 1.0), 7.2% (95% CI 5.3, 9.7), 57.7% (95% CI 53.1, 62.3) and 0.0% (95% CI 0.0, 0.0), respectively. There was no identified risk factor for brucellosis and PPR. The two risk factors for C . burnetii seropositivity were sex (p-value = 0.0005) and commune (p-value .0001). However, only the OR of C . burnetii seropositive female goat was significant at 9.7 (95% CI 2.7, 35.5) times higher than male. The risk factors of FMD NSP seropositivity were age (p-value = 0.001) and commune (p-value .0001). Only the age ’more than two-year-old’ group with a significant OR of 6.2 (95% CI 2.1, 18.4) using the ’up to one-year-old’ group as the reference. In summary, Brucella spp . seroprevalence was low, while no evidence of PPRV antibodies was detected in the goat populations. C . burnetii seroprevalence in female goats was significantly higher than for males, and there were significant differences in C . burnetii seroprevalence between communes. The overall FMDV NSP seroprevalence was high, especially in older animals. Vaccination should be advocated to protect animals from FMDV and improve productivity. As the impacts of these zoonoses on human and animal health were still unknown, further investigation of these zoonotic diseases’ epidemiology is recommended.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 06-12-2010
Publisher: Oxford University Press (OUP)
Date: 09-2012
Publisher: Hindawi Limited
Date: 07-07-2021
DOI: 10.1111/TBED.14193
Publisher: American Society of Tropical Medicine and Hygiene
Date: 05-09-2012
Publisher: Massachusetts Medical Society
Date: 08-09-2016
Publisher: Oxford University Press (OUP)
Date: 23-05-2008
DOI: 10.1111/J.1365-2249.2008.03673.X
Abstract: Scrub typhus is responsible for a large proportion of undifferentiated fevers in south-east Asia. The cellular tropism and pathophysiology of the causative agent, Orientia tsutsugamushi, remain poorly understood. We measured endothelial and leucocyte activation by soluble cell adhesion molecule enzyme-linked immunosorbent assays in 242 Lao and Thai patients with scrub or murine typhus, leptospirosis, dengue, typhoid and uncomplicated falciparum malaria on admission to hospital. Soluble E-selectin (sE-selectin) levels were lowest in dengue, sL-selectin highest in scrub typhus with a high sE-selectin to sL-selectin ratio in leptospirosis patients. In scrub typhus patients elevated sL-selectin levels correlated with the duration of skin rash (P = 0·03) and the presence of eschar (P = 0·03), elevated white blood cell (WBC) count (P = 0·007), elevated lymphocyte (P = 0·007) and neutrophil counts (P = 0·015) and elevated levels of sE-selectin correlated with the duration of illness before admission (P = 0·03), the presence of lymphadenopathy (P = 0·033) and eschar (P = 0·03), elevated WBC (P = 0·005) and neutrophil counts (P = 0·0003). In comparison, soluble selectin levels in murine typhus patients correlated only with elevated WBC counts (P = 0·03 for sE-selectin and sL-selectin). Soluble intercellular adhesion molecule-1 and soluble vascular adhesion molecule-1 levels were not associated significantly with any clinical parameters in scrub or murine typhus patients. The data presented suggest mononuclear cell activation in scrub typhus. As adhesion molecules direct leucocyte migration and induce inflammatory and immune responses, this may represent O. tsutsugamushi tropism during early dissemination, or local immune activation within the eschar.
Publisher: Elsevier BV
Date: 10-2007
DOI: 10.1016/J.RVSC.2006.12.007
Abstract: Here we describe the diagnostic utility of the indirect immunofluorescence assay (IFA) during a recent outbreak of highly pathogenic avian influenza (HPAI) subtype H5N1 virus in southern Thailand and demonstrate the usefulness of the cardiac tissue from infected chickens, quail, and ducks for diagnosis. The most reliable s le for IFA diagnosis of influenza A virus was cardiac tissue (83.0% 44/53) which when ided by species (chicken, quail and duck cardiac tissues) gave respective positivity rates of 88% (22/25), 88.9% (16/18) and 60.0% (6/10). Cardiac tissue also gave the highest IFA intensity for the three species. We believe that the IFA method has wide applicability in developing countries or remote settings where clinically similar avian diseases with high morbidity and mortality such as Newcastle disease and fowl cholera are common and could be rapidly excluded thereby conserving valuable reference laboratory capacity for true HPAI outbreaks.
Publisher: Elsevier BV
Date: 11-2022
Publisher: Oxford University Press (OUP)
Date: 11-2006
Publisher: Elsevier BV
Date: 02-1994
DOI: 10.1016/0166-0934(94)90107-4
Abstract: A fluorescence inhibition test (FIT) is described for serotyping rapidly isolates of epizootic haemorrhagic disease of deer virus (EHDV). The test used a serogroup-reactive monoclonal antibody in a immunofluorescence procedure to detect virus which resisted neutralisation by antisera to any of the eight known EHDV serotypes. The EHDV FIT provided an accurate serotype identification procedure for all eight reference serotypes and, in comparison with the plaque inhibition assay, abbreviated the serotyping process by three to four days.
Publisher: Public Library of Science (PLoS)
Date: 09-05-2016
Publisher: MDPI AG
Date: 08-03-2021
DOI: 10.3390/ANI11030742
Abstract: Although animal health surveillance programmes are useful for gaining information to help improve global health and food security, these programmes can be challenging to establish in developing economies with a low-resource base. This study focused on establishing a national surveillance system initiated by the Lao PDR government using a passive surveillance system of abattoir s les as a pilot model, and to gain information on contagious zoonoses, particularly Q fever and brucellosis, in the large ruminant population. A total of 683 cattle and buffalo s les were collected from six selected provinces of Lao PDR between March–December 2019. Out of 271 s les tested, six s les (2.2%, 95% confidence interval (CI) of 1.0, 4.8) were positive in the Q fever antibody ELISA test. Only one s le (out of 683 0.2%, 95% CI 0.0, 0.8) tested positive to the Brucella antibody ELISA test. Seroprevalence of these important zoonoses in Lao PDR were relatively low in cattle and buffaloes however, extensive animal movement within the country was identified which could increase risks of spreading transboundary diseases. The study highlights the importance of ongoing animal health surveillance and the need to find cost-effective approaches for its long-term sustainability.
Publisher: Cambridge University Press (CUP)
Date: 2019
DOI: 10.1017/S0950268819000578
Abstract: Foot and mouth disease (FMD) is a major animal health problem within Southeast Asia (SEA). Although Indonesia and more recently the Philippines have achieved freedom from FMD, the disease remains endemic on continental SEA. Control of FMD within SEA would increase access to markets in more developed economies and reduce lost productivity in smallholder and emerging commercial farmer settings. However, despite many years of vaccination by in idual countries, numerous factors have prevented the successful control of FMD within the region, including unregulated ‘informal’ transboundary movement of livestock and their products, difficulties implementing vaccination programmes, emergence of new virus topotypes and lineages, low-level technical capacity and biosecurity at national levels, limited farmer knowledge on FMD disease recognition, failure of timely outbreak reporting and response, and limitations in national and international FMD control programmes. This paper examines the published research of FMD in the SEA region, reviewing the history, virology, epidemiology and control programmes and identifies future opportunities for FMD research aimed at the eventual eradication of FMD from the region.
Publisher: Elsevier BV
Date: 24-03-2011
DOI: 10.1016/J.VETMIC.2010.09.028
Abstract: A serological and virological surveillance program to investigate the HPAI H5N1 virus in wild bird populations was undertaken from February 2007 to October 2008. The purpose of the survey was to investigate the infection status in free ranging wild birds in Banglane district, Nakhon Pathom province, central Thailand. S les from wild birds were collected every two months. Choanal and cloacal swabs, serum and tissue s les were collected from 421 birds comprising 44 species. Sero-prevalence of the virus tested by H5N1 serum neutralization test (using a H5N1 virus clade 1 A/chicken/Thailand/vsmu-3-BKK/2004) was 2.1% (8 out of 385 s les 95% CI 0.7, 3.5). Species that were antibody positive included rock pigeons (Columba livia), Asian pied starling (Gracupica contra), spotted dove (Streptopelia chinensis), oriental magpie robin (Copsychus saularis), blue-tailed bee-eater (Merops philippinus), myna (Acridotheres spp.), and pond heron (Ardeola spp.). Prevalence by H5N1 virus isolation was 0.5% (2 out of 421 s les 95% CI 0.0, 1.1) the two H5N1 virus-positive s les were from Asian pied starling (Gracupica contra) and white vented myna (Acridotheres grandis). Positive virological s les were collected in June 2007 while all positive serology s les were collected between May and August except for one s le collected in December 2007. No positive s les were collected in 2008. Molecular studies revealed that the wild bird H5N1 viruses were closely related to poultry viruses isolated in other parts of Thailand. However, there was no poultry H5N1 prevalence study performed in the study site during the time of this wild bird survey. Interpretation of source of virus isolates would include spill-over of H5N1 viruses from contaminated sources due to movement of domestic poultry and/or fomites from other areas or infection of wild birds within the outbreak locations and then translocation by wild bird movement and interaction with wild birds inhabiting distant locations.
Publisher: American Society for Microbiology
Date: 12-2010
DOI: 10.1128/JCM.01526-10
Abstract: In July 2006, an Australian tourist returning from Dubai, in the United Arab Emirates (UAE), developed acute scrub typhus. Her signs and symptoms included fever, myalgia, headache, rash, and eschar. Orientia tsutsugamushi serology demonstrated a 4-fold rise in antibody titers in paired serum collections (1:512 to 1:8,192), with the sera reacting strongest against the Gilliam strain antigen. An Orientia species was isolated by the in vitro culture of the patient's acute blood taken prior to antibiotic treatment. The gene sequencing of the 16S rRNA gene ( rrs ), partial 56-kDa gene, and the full open reading frame 47-kDa gene was performed, and comparisons of this new Orientia sp. isolate to previously characterized strains demonstrated significant sequence ersity. The closest homology to the rrs sequence of the new Orientia sp. isolate was with three strains of O. tsutsugamushi (Ikeda, Kato, and Karp), with a nucleotide sequence similarity of 98.5%. The closest homology to the 47-kDa gene sequence was with O. tsutsugamushi strain Gilliam, with a nucleotide similarity of 82.3%, while the closest homology to the 56-kDa gene sequence was with O. tsutsugamushi strain TA686, with a nucleotide similarity of 53.1%. The molecular ergence and geographically unique origin lead us to believe that this organism should be considered a novel species. Therefore, we have proposed the name “ Orientia chuto ,” and the prototype strain of this species is strain Dubai, named after the location in which the patient was infected.
Publisher: Elsevier BV
Date: 05-2009
Publisher: American Physiological Society
Date: 04-2014
DOI: 10.1152/JAPPLPHYSIOL.01245.2013
Abstract: Caudal tracheal displacement (TD) leads to improvements in upper airway (UA) function and decreased collapsibility. To better understand the mechanisms underlying these changes, we examined effects of TD on peripharyngeal tissue stress distributions [i.e., extraluminal tissue pressure (ETP)], deformation of its topographical surface (UA lumen geometry), and hyoid bone position. We studied 13 supine, anesthetized, tracheostomized, spontaneously breathing, adult male New Zealand white rabbits. Graded TD was applied to the cranial tracheal segment from 0 to ∼10 mm. ETP was measured at six locations distributed around/along the length of the UA, covering three regions: tongue, hyoid, and epiglottis. Axial images of the UA (nasal choanae to glottis) were acquired with computed tomography and used to measure lumen geometry (UA length regional cross-sectional area) and hyoid bone displacement. TD resulted in nonuniform decreases in ETP (generally greatest at tongue region), ranging from −0.07 (−0.11 to −0.03) [linear mixed-effects model slope (95% confidence interval)] to −0.27 (−0.31 to −0.23) cmH 2 O/mm TD, across all sites. UA length increased by 1.6 (1.5–1.8)%/mm, accompanied by nonuniform increases in cross-sectional area (greatest at hyoid region) ranging from 2.8 (1.7–3.9) to 4.9 (3.8–6.0)%/mm. The hyoid bone was displaced caudally by 0.22 (0.18–0.25) mm/mm TD. In summary, TD imposes a load on the UA that results in heterogeneous changes in peripharyngeal tissue stress distributions and resultant lumen geometry. The hyoid bone may play a pivotal role in redistributing applied caudal tracheal loads, thus modifying tissue deformation distributions and determining resultant UA geometry outcomes.
Publisher: Wiley
Date: 19-02-2021
Publisher: Oxford University Press (OUP)
Date: 02-2008
DOI: 10.1016/J.TRSTMH.2007.11.001
Abstract: The high incidence of rickettsial diseases in Southeast Asia necessitates rapid and accurate diagnostic tools for a broad range of rickettsial agents, including Orientia tsutsugamushi (scrub typhus) and Rickettsia typhi (murine typhus), but also spotted fever group infections, which are increasingly reported. We present an SYBR-Green-based, real-time multiplex PCR assay for rapid identification and differentiation of scrub typhus group, typhus group and spotted fever group rickettsiae using 47kDa, gltA and ompB gene targets. Detection limits for lification of these genes in reference strains ranged from 24 copies/microl, 5 copies/microl and 1 copy/microl in multiplex and 2 copies/microl, 1 copy/microl and 1 copy/microl in single template format, respectively. Differentiation by melt-curve analysis led to distinct melt temperatures for each group-specific licon. The assay was subjected to 54 s les, of which all cell-culture and 75% of characterised clinical buffy coat s les were correctly identified. Real-time PCR has the advantage of reliably detecting and differentiating rickettsial and orientia cell-culture isolates in a single-template assay, compared with the more time-consuming and laborious immunofluorescence assay. However, further optimisation and validation on s les taken directly from patients to assess its clinical diagnostic utility is required.
Publisher: Public Library of Science (PLoS)
Date: 06-04-2016
Publisher: Public Library of Science (PLoS)
Date: 10-01-2012
Publisher: Elsevier BV
Date: 09-2008
DOI: 10.1016/J.PARINT.2008.04.002
Abstract: Taeniasis and cysticercosis are important but underreported parasitic zoonoses in the Lao People's Democratic Republic (Lao PDR). Reports of human and pig cysticercosis are rather limited and based largely on anecdotal evidence. To date, no structured surveys of disease prevalence or incidence have been reported. However, one unpublished pilot survey of pig cysticercosis in a slaughterhouse in northern Laos estimated prevalence to be 1.7%, without speciation of parasite cysts. Over the past 20 years, nine surveys of intestinal helminthic infection have been conducted the prevalence of human taeniasis ranged from 0 to 14.0%. The study designs and s le sizes varied greatly, however a high degree of spatial and age variation in taeniasis prevalence was evident. These results are however inconclusive as the species of tapeworm infecting the people was not determined. To further our knowledge of taeniasis and cysticercosis in Lao PDR, structured community-based surveys in high-risk areas are required in combination with the use of sensitive and specific diagnostic tests capable of identifying the pork tapeworm, Taenia solium. This will enable the development and implementation of control measures that are both appropriate and sustainable if T. solium is shown to be a public health threat.
Publisher: American Society for Microbiology
Date: 10-2015
DOI: 10.1128/CVI.00390-15
Abstract: This study investigated the comparative accuracy of a recombinant 56-kDa type-specific antigen-based rapid diagnostic test (RDT) for scrub typhus for the detection of IgM antibodies by using conventional serology in well-characterized serum s les from undifferentiated febrile illness patients. The RDT showed high specificity and promising comparative accuracy, with 82% sensitivity and 98% specificity for s les defined positive at an IgM indirect immunofluorescence assay positivity cutoff titer of ≥1:1,600 versus 92% and 95% at ≥1:6,400, respectively.
Publisher: Public Library of Science (PLoS)
Date: 29-05-2015
Publisher: Public Library of Science (PLoS)
Date: 05-02-2016
Publisher: Hindawi Limited
Date: 10-05-2023
DOI: 10.1155/2023/5151813
Abstract: African swine fever (ASF) is a devastating transboundary disease of swine. Following the first report of ASF in China in August 2018, ASF spread through South-East Asian nations in 2019. Without control and containment measures, ASF can decimate smallholder pig holdings and disrupt value chains. This study aimed to describe the spatiotemporal spread of the 2019 Lao PDR ASF epidemic in domestic pigs, identify environmental (protected areas and forests), production (pig ownership), transportation (roads), and social (poverty and ethnicity) risk factors, and recommend measures that could reduce ASF spread. A retrospective spatiotemporal study was conducted at the village level. Information on the date that ASF was first reported from each case location was collected, and the outcome variable of interest “epidemic day” was created. Risk factor information from different sources was extracted for each case location. The association or correlation between epidemic day and risk factors for the spread of ASF was investigated using Kruskal–Wallis tests and Spearman rank correlation statistics. The epidemic started on June 16 and lasted for 190 days, displaying a right-skewed epidemic curve. The directional distribution was rotated approximately 305°, from Southeast to Northwest Laos. Significant risk factors for ASF associated with epidemic day were location in terms of distance from the closest protected natural area P = 0.020 , pig ownership P = 0.005 , road networks P = 0.003 , and poverty indices P 0.001 . Cases were reported earlier in this epidemic at locations that were closer to protected natural areas, of higher pig ownership, more connected via the national road network, and which experienced elevated poverty. The spatiotemporal pattern described suggests that ASF was introduced via infected pigs from Vietnam. Based on study findings, recommendations for smallholder pig production in Southeast Asia include improving knowledge of swine value chains to inform disease risk and control, monitoring pig transportation, implementing stricter biosecurity measures on the domestic pig population, and providing biosecurity support and education to smallholder pig farmers in poverty.
Publisher: Springer Science and Business Media LLC
Date: 29-11-2009
DOI: 10.1007/S11250-008-9279-2
Abstract: Classical swine fever (CSF) is a highly contagious and severe viral disease of swine resulting in substantial production losses in different farming systems in many regions of the world. The accurate and rapid detection of CSF outbreaks is reliant on sensitive and specific laboratory testing and is a key component of disease control. Specific detection of CSF virus can be achieved by virus isolation in tissue culture, antigen capture or the detection of viral RNA using molecular techniques. In order to reduce the time taken to achieve a diagnostic result and simplify testing methods, an antigen capture ELISA using immunomagnetic beads (IMB) as the solid phase was developed and compared to a microplate-based antigen capture (AC)-ELISA. The IMB-ELISA has up to 64-fold greater analytical sensitivity than the AC-ELISA and initial estimates of diagnostic sensitivity and specificity are 100%. The IMB-ELISA has a highly robust, rapid and stable test format and is simpler to perform than the AC-ELISA. The IMB-ELISA has the added advantage that a result can be sensitively and specifically determined by eye, lending it to the possibility of adaptation to a near-to-field test with minimal equipment or expertise needed.
Publisher: Wiley
Date: 12-1982
Publisher: The American Association of Immunologists
Date: 03-2021
Abstract: Prophylactic human papillomavirus (HPV) vaccines are commercially available for prevention of infection with cancerogenic HPV genotypes but are not able to combat pre-existing HPV-associated disease. In this study, we designed a nanomaterial-based therapeutic HPV vaccine, comprising manganese (Mn4+)-doped silica nanoparticles (Mn4+-SNPs) and the viral neoantigen peptide GF001 derived from the HPV16 E7 oncoprotein. We show in mice that Mn4+-SNPs act as self-adjuvants by activating the inflammatory signaling pathway via generation of reactive oxygen species, resulting in immune cell recruitment to the immunization site and dendritic cell maturation. Mn4+-SNPs further serve as Ag carriers by facilitating endo/lysosomal escape via depletion of protons in acidic endocytic compartments and subsequent Ag delivery to the cytosol for cross-presentation. The Mn4+-SNPs+GF001 nanovaccine induced strong E7-specific CD8+ T cell responses, leading to remission of established murine HPV16 E7-expressing solid TC-1 tumors and E7-expressing transgenic skin grafts. This vaccine construct offers a simple and general strategy for therapeutic HPV and potentially other cancer vaccines.
Publisher: Elsevier BV
Date: 02-2013
Publisher: MDPI AG
Date: 09-2018
DOI: 10.3390/TROPICALMED3030095
Abstract: Here we estimated the accuracy of the InBios Scrub Typhus Detect™ immunoglobulin M (IgM) ELISA to determine the optimal optical density (OD) cut-off values for the diagnosis of scrub typhus. Patients with undifferentiated febrile illness from Chittagong, Bangladesh, provided s les for reference testing using (i) qPCR using the Orientia spp. 47-kDa htra gene, (ii) IFA ≥1:3200 on admission, (iii) immunofluorescence assay (IFA) ≥1:3200 on admission or 4-fold rise to ≥3200, and (iv) combination of PCR and IFA positivity. For sero-epidemiological purposes (ELISA vs. IFA ≥1:3200 on admission or 4-fold rise to ≥3200), the OD cut-off for admission s les was ≥1.25, resulting in a sensitivity (Sn) of 91.5 (95% confidence interval (95% CI: 96.8–82.5) and a specificity (Sp) of 92.4 (95% CI: 95.0–89.0), while for convalescent s les the OD cut-off was ≥1.50 with Sn of 66.0 (95% CI: 78.5–51.7) and Sp of 96.0 (95% CI: 98.3–92.3). Comparisons against comparator reference tests (ELISA vs. all tests including PCR) indicated the most appropriate cut-off OD to be within the range of 0.75–1.25. For admission s les, the best Sn/Sp compromise was at 1.25 OD (Sn 91.5%, Sp 92.4%) and for convalescent s les at 0.75 OD (Sn 69.8%, Sp 89.5%). A relatively high (stringent) diagnostic cut-off value provides increased diagnostic accuracy with high sensitivity and specificity in the majority of cases, while lowering the cut-off runs the risk of false positivity. This study underlines the need for regional assessment of new diagnostic tests according to the level of endemicity of the disease given the high levels of residual or cross-reacting antibodies in the general population.
Publisher: Mary Ann Liebert Inc
Date: 03-2010
Publisher: MDPI AG
Date: 31-01-2019
DOI: 10.3390/TROPICALMED4010023
Abstract: Murine typhus is a rarely diagnosed cause of acute febrile illness in Malaysia, and its true disease burden is unknown. We report a case of an acute murine typhus infection in a patient living in a small city in Peninsular Malaysia, presenting with fever, rash, and headache. Unresponsive to the initial empirical treatment for leptospirosis, he showed a rapid response to doxycycline when murine typhus was diagnosed later. This case highlights the importance of considering murine typhus as a diagnostic in cases of acute febrile illness in urban and sub-urban areas, such as that of in Peninsular Malaysia.
Publisher: American Society for Microbiology
Date: 10-2011
DOI: 10.1128/CVI.05288-11
Abstract: A Sri Lankan fever cohort ( n = 292 patients 17.8% prevalence) was used to assess two standard diagnostic Chikungunya IgM tests. The immunochromatographic test (ICT) acute s le sensitivity (SN) was 1.9 to 3.9%, and specificity (SP) was 92.5 to 95.0%. The enzyme-linked immunosorbent assay (ELISA) gave an acute s le SN of 3.9% and an SP of 92.5% and a convalescent s le SN of 84% and an SP of 91%. These assays are not suitable for the acute diagnosis of Chikungunya virus infection.
Publisher: Elsevier BV
Date: 08-2004
Publisher: Elsevier BV
Date: 04-1998
DOI: 10.1016/S0168-1702(98)00025-2
Abstract: A novel lyssavirus isolated from Pteropid bats in Australia (Australian Bat Lyssavirus, ABLV) has been characterised using gene sequence analyses, electron microscopy and a panel of monoclonal antibodies. Electron microscopic examination of Pteropid bat and mouse brain material as well as virus isolated from tissue culture medium, showed the presence of bullet-shaped rhabdovirus particles and structures characteristic of lyssavirus. Analysis using nucleocapsid (N) specific monoclonal antibodies, showed a strong relationship between this new lyssavirus and serotype 1 rabies. The nucleotide sequence of the prototype strain of ABLV was determined from the initiator methionine codon for the nucleocapsid protein (N protein) to the amino terminus of the polymerase gene (L protein), a distance of 5344 nucleotides. Comparisons of the deduced N, phosphoprotein (P), matrix protein (M), and glycoprotein (G) proteins showed that ABLV was more closely related to serotype 1 classic rabies viruses than to other members of the Lyssavirus genus. The percent relatedness of the ABLV proteins when compared to the cognate proteins of PV (Pasteur vaccine strain) rabies was 92, 75, 87 and 75% for the N, P, M and G proteins, respectively. Phylogenetic studies of N protein sequences showed clearly that ABLV is an unrecognised member of the Lyssavirus genus and represents a new genotype, genotype 7.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 09-12-2015
Publisher: MDPI AG
Date: 14-03-2018
Publisher: Elsevier BV
Date: 10-1993
DOI: 10.1016/0166-0934(93)90059-Z
Abstract: Rapid serotyping of bluetongue virus (BTV) isolates is required to facilitate the choice of an appropriate serotype-specific vaccine in a disease situation or to improve surveillance of BTV serotype prevalence. This communication describes the development and validation of a bluetongue virus fluorescent inhibition test (BTV FIT) as a rapid method to serotype Australian BTV isolates. The BTV FIT uses virus neutralisation principles similar to those used in the rabies rapid fluorescent focus inhibition test. The BTV FIT has the ability to provide an accurate serotype identification within 24 h thereby abbreviating the serotyping process by 3-4 days relative to conventional virus neutralisation assays and making the BTV FIT comparable time-wise with the polymerase chain reaction technique. The development of the BTV FIT is described using BTV reference viruses which have been isolated in Australia, and validation of the assay by assessment of five Australian BTV isolates of unknown serotype by comparison with the plaque inhibition method. The use of the BTV FIT readily facilitated rapid and accurate serotype identification of Australian BTV reference viruses and five unknown BTV isolates with results indicating full agreement with the plaque inhibition method.
Publisher: Public Library of Science (PLoS)
Date: 06-2016
Publisher: Elsevier BV
Date: 12-2012
Publisher: Oxford University Press (OUP)
Date: 06-2007
DOI: 10.1111/J.1574-6968.2007.00711.X
Abstract: Molecular typing of leptospiral strains based on variation within putative O-antigen polymerase gene (wzy) was determined among reference strains and those isolated from patients. Using the PCR primers designed from the flanking gene of wzy derived from Leptospira interrogans serovar Copenhageni, all L. interrogans serovars as well as human and rodent leptospiral isolates from Thailand could be lified. The size of PCR product ranged from 1 to 1.5 kb. The limitation of these primer pairs was the inability to lify those strains whose sequences differ in the region of the primers, these included Leptospira biflexa (serovar Patoc), Leptospira borgpetersenii (serovar Tarassovi) and Leptospira kirschneri (serovar Bim, Bulgarica, Butembo). Notably, lification was not limited to L. interrogans as demonstrated by the lification of some strains from L. kirschneri, Leptospira meyeri, Leptospira noguchii, Leptospira santarosai, L. borgpetersenii and Leptospira weilii. The phylogenetic tree of wzy sequence, inferred by posterior probability of the Bayesian, enabled the categorization of leptospiral serovars into seven genetically related group, of which its differentiation power was better than that of the more highly conserved 16S rRNA gene, which is used extensively for genotyping.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 05-08-2010
Publisher: Public Library of Science (PLoS)
Date: 04-02-2019
Publisher: Public Library of Science (PLoS)
Date: 16-11-2010
Publisher: American Physiological Society
Date: 04-2012
DOI: 10.1152/JAPPLPHYSIOL.01286.2011
Abstract: Increasing lung volume improves upper airway airflow dynamics via passive mechanisms such as reducing upper airway extraluminal tissue pressures (ETP) and increasing longitudinal tension via tracheal displacement. We hypothesized a threshold lung volume for optimal mechanical effects on upper airway airflow dynamics. Seven supine, anesthetized, spontaneously breathing New Zealand White rabbits were studied. Extrathoracic pressure was altered, and lung volume change, airflow, pharyngeal pressure, ETP laterally (ETPlat) and anteriorly (ETPant), tracheal displacement, and sternohyoid muscle activity (EMG%max) monitored. Airflow dynamics were quantified via peak inspiratory airflow, flow limitation upper airway resistance, and conductance. Every 10-ml lung volume increase resulted in caudal tracheal displacement of 2.1 ± 0.4 mm (mean ± SE), decreased ETPlat by 0.7 ± 0.3 cmH 2 O, increased peak inspiratory airflow of 22.8 ± 2.6% baseline (all P 0.02), and no significant change in ETPant or EMG%max. Flow limitation was present in most rabbits at baseline, and abolished 15.7 ± 10.5 ml above baseline. Every 10-ml lung volume decrease resulted in cranial tracheal displacement of 2.6 ± 0.4 mm, increased ETPant by 0.9 ± 0.2 cmH 2 O, ETPlat was unchanged, increased EMG%max of 11.1 ± 0.3%, and a reduction in peak inspiratory airflow of 10.8 ± 1.0%baseline (all P 0.01). Lung volume, resistance, and conductance relationships were described by exponential functions. In conclusion, increasing lung volume displaced the trachea caudally, reduced ETP, abolished flow limitation, but had little effect on resistance or conductance, whereas decreasing lung volume resulted in cranial tracheal displacement, increased ETP and increased resistance, and reduced conductance, and flow limitation persisted despite increased muscle activity. We conclude that there is a threshold for lung volume influences on upper airway airflow dynamics.
Publisher: Public Library of Science (PLoS)
Date: 12-04-2016
Publisher: Oxford University Press (OUP)
Date: 07-2010
Publisher: Elsevier BV
Date: 06-1997
DOI: 10.1016/S0166-0934(97)00046-3
Abstract: The Bunyavirus genus, belonging to the Bunyaviridae family, is comprised of a large group of antigenically and geographically disparate arthropod-borne viruses of medical and veterinary significance. In Australia, viruses belonging to the Simbu serogroup of the Bunyavirus genus, Akabane, Tinaroo, Peaton, Aino, Douglas, Thimiri and Facey's Paddock have been isolated. In this communication we describe two indirect ELISAs, referred to as the Simbu serogroup ELISA (SG-ELISA), and the Simbu typing ELISA (ST-ELISA), for the identification of these Simbu serogroup viruses. Infected cell lysate antigens prepared from Simbu serogroup virus isolates were assessed in the SG-ELISA for reactivity with a mouse monoclonal antibody (4H9/B11/F1). The monoclonal antibody reacted strongly with all Australian members of Simbu serogroup reference viruses and is proposed for use as a serogrouping reagent for Simbu viruses. Furthermore, the ST-ELISA enabled specific identification of viruses from within this group by recognition of characteristic reaction patterns between infected cell lysate antigens and a panel of polyclonal antisera raised to Simbu serogroup viruses.
Publisher: Centers for Disease Control and Prevention (CDC)
Date: 02-2006
Abstract: Rickettsial diseases have not been described previously from Laos, but in a prospective study, acute rickettsial infection was identified as the cause of fever in 115 (27%) of 427 adults with negative blood cultures admitted to Mahosot Hospital in Vientiane, Laos. The organisms identified by serologic analysis were Orientia tsutsugamushi (14.8%), Rickettsia typhi (9.6%), and spotted fever group rickettsia (2.6% [8 R. helvetica, 1 R. felis, 1 R. conorii subsp. indica, and 1 Rickettsia "AT1"]). Patients with murine typhus had a lower frequency of peripheral lymphadenopathy than those with scrub typhus (3% vs. 46%, p<0.001). Rickettsioses are an underrecognized cause of undifferentiated febrile illnesses among adults in Laos. This finding has implications for the local empiric treatment of fever.
Publisher: Wiley
Date: 1996
DOI: 10.1111/J.1751-0813.1996.TB09953.X
Abstract: To explore the related risk factors of postoperative delirium (POD) after hip or knee arthroplasty in elderly orthopedic patients and the predictive value of related risk factors. 58 patients were included in each group after propensity score matching multivariable analysis demonstrated that LDH (OR = 4.364, Our study revealed that arrhythmia, operation duration, the increase of lactate dehydrogenase and Cystatin C, and the decrease of cholinesterase were reliable factors for predicting postoperative delirium after elderly hip and knee arthroplasty. Meanwhile, the nomogram we developed can assist the clinician to filtrate potential patients with postoperative delirium.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1SC05319A
Abstract: Na- IV Al-DMSN acts as both antigen carriers and modulators to “hyperactivate” dendritic cells (DCs) via potassium (K + ) efflux dependent pyroptosis, eventually leading to enhanced adaptive and innate immunity.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 04-2012
Publisher: Wiley
Date: 26-07-2012
DOI: 10.1111/J.1863-2378.2012.01515.X
Abstract: A questionnaire was used to collect data on small poultry farm management and wild bird observed in poultry keeping areas to identify putative risk factors for infection with HPAI H5N1. The study was conducted in 2008 in four subdistricts of central Thailand that had experienced outbreaks of HPAI H5N1 in poultry. Descriptive and inferential analyses including univariable analyses and multivariable logistic regression were used to identify putative risk factors. Risk factors included purchasing native chickens/fighting cocks from commercial hatcheries, replacing or restocking birds in idually, and observing lesser whistling ducks (Dendrocygna javanica) on the farm daily. Selecting healthy animals when purchasing animals to ensure that they were disease free was a protective factor. To fully understand the epidemiology of infection of small poultry farms with HPAI H5N1, control of movement of domestic poultry and serological and virological testing of the poultry population should be applied.
Publisher: Elsevier BV
Date: 2022
Location: No location found
Location: Australia
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Stuart Blacksell.