ORCID Profile
0000-0003-2046-1093
Current Organisations
Université Paris Cité
,
University of Peradeniya
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Publisher: Public Library of Science (PLoS)
Date: 12-12-2022
DOI: 10.1371/JOURNAL.PONE.0278920
Abstract: Human intestinal nematode infections are a global public health issue as they can result in considerable morbidity in infected in iduals, mainly in developing countries. These infections continue to go undiagnosed, as they tend to be mainly endemic in resource-poor communities where there is a shortage of experienced laboratory staff and relevant diagnostic technologies. This is further exacerbated by the nature of intermittent shedding of eggs and larvae by these parasites. Diagnostic methods range from simple morphological identification to more specialised high-throughput sequencing technologies. Microscopy-based methods, although simple, are labour-intensive and considerably less sensitive than molecular methods which are rapid and have high levels of accuracy. Molecular methods use nucleic acid lification (NAA) to lify the deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) fragments of the parasite to detect and determine its presence using different technologies (NAAT). They have increased the sensitivity of detection and quantitation of intestinal nematode infections, especially in low infection intensity settings. The absence of a gold standard test limits current diagnosis and, in turn, restricts intervention measures and effective control efforts. The objective of this review is to determine the accuracy of NAATs in detecting human intestinal nematode infections using Kato-Katz as the reference test for the most common soil-transmitted helminth (STH) infections and the scotch tape test for enterobiasis and Baermann method for strongyloidiasis. Relevant studies will be identified by searches in electronic databases. Two reviewers will independently screen the literature against eligibility criteria. The methodological quality of studies will then be appraised by two reviewers using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Discrepancies will be addressed by a third reviewer. The true positives, false positives, true negatives and false negatives of all the studies will be extracted into contingency tables. In paired forest plots, study-specific sensitivity and specificity with a 95 per cent confidence interval will be displayed. The systematic review of this protocol will report the diagnostic accuracy of currently available NAATs for the detection of human intestinal nematode infections. This will help healthcare providers and administrators determine the diagnostic method to be used in different clinical and preventive settings. Trial registration : PROSPERO registration number for this protocol is CRD42022315730 .
Publisher: Public Library of Science (PLoS)
Date: 26-05-2021
DOI: 10.1371/JOURNAL.PMED.1003632
Abstract: A very large biomass of intact asexual-stage malaria parasites accumulates in the spleen of asymptomatic human in iduals infected with Plasmodium vivax . The mechanisms underlying this intense tropism are not clear. We hypothesised that immature reticulocytes, in which P . vivax develops, may display high densities in the spleen, thereby providing a niche for parasite survival. We examined spleen tissue in 22 mostly untreated in iduals naturally exposed to P . vivax and Plasmodium falciparum undergoing splenectomy for any clinical indication in malaria-endemic Papua, Indonesia (2015 to 2017). Infection, parasite and immature reticulocyte density, and splenic distribution were analysed by optical microscopy, flow cytometry, and molecular assays. Nine non-endemic control spleens from in iduals undergoing spleno-pancreatectomy in France (2017 to 2020) were also examined for reticulocyte densities. There were no exclusion criteria or s le size considerations in both patient cohorts for this demanding approach. In Indonesia, 95.5% (21/22) of splenectomy patients had asymptomatic splenic Plasmodium infection (7 P . vivax , 13 P . falciparum , and 1 mixed infection). Significant splenic accumulation of immature CD71 intermediate- and high-expressing reticulocytes was seen, with concentrations 11 times greater than in peripheral blood. Accordingly, in France, reticulocyte concentrations in the splenic effluent were higher than in peripheral blood. Greater rigidity of reticulocytes in splenic than in peripheral blood, and their higher densities in splenic cords both suggest a mechanical retention process. Asexual-stage P . vivax -infected erythrocytes of all developmental stages accumulated in the spleen, with non-phagocytosed parasite densities 3,590 times (IQR: 2,600 to 4,130) higher than in circulating blood, and median total splenic parasite loads 81 (IQR: 14 to 205) times greater, accounting for 98.7% (IQR: 95.1% to 98.9%) of the estimated total-body P . vivax biomass. More reticulocytes were in contact with sinus lumen endothelial cells in P . vivax - than in P . falciparum -infected spleens. Histological analyses revealed 96% of P . vivax rings/trophozoites and 46% of schizonts colocalised with 92% of immature reticulocytes in the cords and sinus lumens of the red pulp. Larger splenic cohort studies and similar investigations in untreated symptomatic malaria are warranted. Immature CD71 + reticulocytes and splenic P . vivax- infected erythrocytes of all asexual stages accumulate in the same splenic compartments, suggesting the existence of a cryptic endosplenic lifecycle in chronic P . vivax infection. Findings provide insight into P . vivax -specific adaptions that have evolved to maximise survival and replication in the spleen.
Publisher: Springer Science and Business Media LLC
Date: 05-04-2022
DOI: 10.1007/S11686-022-00543-3
Abstract: Sri Lanka has reported the highest prevalence of human dirofilariasis cases in Asia. Thus far, Dirofilaria repens is the only reported Dirofilaria species that affect humans, dogs, and cats in Sri Lanka. Therefore, this systematic review was carried out to analyse the studies performed on dirofilariasis in Sri Lanka. Peer-reviewed articles were searched on dirofilariasis published on Google Scholar, PubMed, Cochrane, and ResearchGate from January to March 2021. Articles were selected using inclusion and exclusion criteria. Three reviewers assessed the studies and extracted data independently to minimize the risk of bias. Extracted data were compiled, and then the results were compared and discussed in this systematic review. Twenty-five studies performed in Sri Lanka were analysed, and high prevalence areas, frequent clinical presentations, diagnostic methods, reservoir hosts, and treatment were identified. More than 173 cases of human dirofilariasis caused by D. repens were reported from 1962 to 2020 in 20 districts among 25 investigated. The highest number of cases (n = 80) was recorded during 2010-2012 period. Canine and feline dirofilariasis are reported countrywide, and a large number of potential mosquito breeding sites could be seen in Sri Lanka. The number of reported cases of human dirofilariasis has been varied from 1962 to 2020. The highest number of cases has reported in 2010-2012, and then the number of cases has dropped. This may be due to underreporting. Thus, awareness of Dirofilaria repens infection in humans, control measures in endemic areas and further research on dirofilariasis in other districts of Sri Lanka are crucial.
Publisher: Public Library of Science (PLoS)
Date: 13-10-2021
DOI: 10.1371/JOURNAL.PONE.0258556
Abstract: Trichomonas vaginalis infection is underreported due to nonspecific clinical presentation and the nonavailability of sensitive laboratory diagnostic tests at the clinical setup. Hence, this study was designed to compare the sensitivity and specificity of microscopy and culture methods with polymerase chain reaction (PCR). The socio-demographic factors associated with the infection were explored. The study was carried out at the National Sexually Transmitted Diseases and Acquired Immuno Deficiency Syndrome Control Programme in Colombo and Sexually Transmitted Diseases and Acquired Immuno Deficiency Syndrome Control Programme in Kandy. S les were collected from a total of 385 patients including, 272 females (70.7%) and 113 males (29.3%), and tested using microscopy (wet mount and Giemsa staining), culture, and PCR. Genus-specific primer set (TFR1/TFR2) that lifies 5.8S rRNA and species-specific primer sets (TV16Sf-2/TV16Sr-2 and TVK3/7) that lifies 18S rRNA and repetitive DNA, respectively, were used. Patient’s socio-demographic and sexual behaviour data were obtained using a standard interviewer-administered questionnaire. Data were analyzed with R statistical software Version 3.6.3. The overall prevalence of trichomoniasis was 4.4% (17/385). Of these, six (1.6%) were positive for microscopic examination, 7 (1.8%) were positive for culture, and 13 (3.4%) for TVK3/7, 15 (3.9%) for TV16Sf/r, and TFR1/2 17 (4.4%) were positive for PCR. Sensitivities of PCR using TFR1/2, TV16Sf/r, and TVK3/7 primer sets were 100%, 88.20%, and 76.50%, respectively, against the expanded gold standard. Trichomoniasis was associated with age above 36 ( p = 0.033), not using condoms in last three months ( p = 0.016), multiple sex partners ( p = 0.001), reason for attendance ( p = 0.027), symptomatic nature ( p = 0.015), and the presence of other sexually transmitted diseases ( p = 0.001). The study highlighted that age over 36 years, multiple sex partners, not using condoms, reason for attendance, symptomatic nature, and having other sexually transmitted diseases can increase the risk of acquiring trichomoniasis. Furthermore, this study confirmed PCR as highly sensitive and specific diagnostic test for the diagnosis of trichomoniasis in comparison to microscopy and culture methods.
Publisher: Massachusetts Medical Society
Date: 27-05-2021
DOI: 10.1056/NEJMC2023884
No related grants have been discovered for Susiji Wickramasinghe.