ORCID Profile
0000-0002-2037-2165
Current Organisation
University of Malaya
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Publisher: American Society for Microbiology
Date: 10-2013
DOI: 10.1128/AAC.00682-13
Abstract: Ex vivo antimalarial sensitivity testing in human malaria parasites has largely depended on microscopic determination of schizont maturation. While this microscopic method is sensitive, it suffers from poor precision and is laborious. The recent development of portable, low-cost cytometers has allowed us to develop and validate a simple, field-optimized protocol using SYBR green and dihydroethidium for the accurate and objective determination of antimalarial drug sensitivity in freshly isolated Plasmodium vivax and Plasmodium falciparum .
Publisher: American Society of Hematology
Date: 27-02-2018
DOI: 10.1182/BLOODADVANCES.2017013730
Abstract: RBC-D is reduced in humans with knowlesi malaria in proportion to disease severity. In humans, but not the macaque hosts, deformability of uRBCs is reduced and is related to the presence of echinocytes.
Publisher: Public Library of Science (PLoS)
Date: 23-10-2013
Publisher: Elsevier BV
Date: 04-2019
Publisher: Elsevier BV
Date: 11-2021
Publisher: American Society of Tropical Medicine and Hygiene
Date: 12-07-2017
Publisher: Oxford University Press (OUP)
Date: 07-2015
Publisher: Springer Science and Business Media LLC
Date: 03-07-2014
Publisher: American Society of Tropical Medicine and Hygiene
Date: 06-06-2018
Publisher: American Society of Hematology
Date: 05-2014
DOI: 10.1182/BLOOD-2013-12-541698
Abstract: P vivax infected cells rosette exclusively to normocytes. Thus, rosetting does not directly facilitate P vivax merozoite invasion. Glycophorin C (CD236R) mediates vivax malaria parasite rosetting. This finding will help in the search for the P vivax rosette ligand.
Publisher: Oxford University Press (OUP)
Date: 25-04-2016
DOI: 10.1093/JME/TJW014
Abstract: We report a case of human intestinal myiasis in a 41-yr-old female patient presented at a clinic in Seri Kembangan, Selangor, Malaysia. Larvae passed out in the patient's feces were sent to the Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. DNA barcoding confirmed the second case of intestinal myiasis in Malaysia involving the larvae of Clogmia albipunctatus (Duckhouse) (Diptera: Psychodidae). We review reported cases of myiasis and discuss the present case of intestinal myiasis in an urban patient.
Publisher: Public Library of Science (PLoS)
Date: 05-08-2016
DOI: 10.1371/JOURNAL.PNTD.0004915
Abstract: Infection by the simian malaria parasite, Plasmodium knowlesi, can lead to severe and fatal disease in humans, and is the most common cause of malaria in parts of Malaysia. Despite being a serious public health concern, the geographical distribution of P. knowlesi malaria risk is poorly understood because the parasite is often misidentified as one of the human malarias. Human cases have been confirmed in at least nine Southeast Asian countries, many of which are making progress towards eliminating the human malarias. Understanding the geographical distribution of P. knowlesi is important for identifying areas where malaria transmission will continue after the human malarias have been eliminated. A total of 439 records of P. knowlesi infections in humans, macaque reservoir and vector species were collated. To predict spatial variation in disease risk, a model was fitted using records from countries where the infection data coverage is high. Predictions were then made throughout Southeast Asia, including regions where infection data are sparse. The resulting map predicts areas of high risk for P. knowlesi infection in a number of countries that are forecast to be malaria-free by 2025 (Malaysia, Cambodia, Thailand and Vietnam) as well as countries projected to be eliminating malaria (Myanmar, Laos, Indonesia and the Philippines). We have produced the first map of P. knowlesi malaria risk, at a fine-scale resolution, to identify priority areas for surveillance based on regions with sparse data and high estimated risk. Our map provides an initial evidence base to better understand the spatial distribution of this disease and its potential wider contribution to malaria incidence. Considering malaria elimination goals, areas for prioritised surveillance are identified.
Publisher: Springer Science and Business Media LLC
Date: 08-07-2019
DOI: 10.1038/S41598-019-46398-Z
Abstract: The zoonotic Plasmodium knowlesi parasite is the most common cause of human malaria in Malaysia. Genetic analysis has shown that the parasites are ided into three subpopulations according to their geographic origin (Peninsular or Borneo) and, in Borneo, their macaque host ( Macaca fascicularis or M . nemestrina ). Whilst evidence suggests that genetic exchange events have occurred between the two Borneo subpopulations, the picture is unclear in less studied Peninsular strains. One difficulty is that P . knowlesi infected in iduals tend to present with low parasitaemia leading to s les with insufficient DNA for whole genome sequencing. Here, using a parasite selective whole genome lification approach on unprocessed blood s les, we were able to analyse recent genomes sourced from both Peninsular Malaysia and Borneo. The analysis provides evidence that recombination events are present in the Peninsular Malaysia parasite subpopulation, which have acquired fragments of the M . nemestrina associated subpopulation genotype, including the DBPβ and NBPXa erythrocyte invasion genes. The NBPXb invasion gene has also been exchanged within the macaque host-associated subpopulations of Malaysian Borneo. Our work provides strong evidence that exchange events are far more ubiquitous than expected and should be taken into consideration when studying the highly complex P . knowlesi population structure.
Publisher: Public Library of Science (PLoS)
Date: 10-08-2016
Publisher: Elsevier BV
Date: 04-2020
DOI: 10.1016/J.ACTATROPICA.2020.105330
Abstract: The public health burden of dengue is most likely under reported. Current dengue control measures only considered symptomatic dengue transmission. Hence, there is a paucity of information on the epidemiology of inapparent dengue. This study reports that many people have been unknowingly exposed to dengue infection. Almost 10% and 70% of in iduals without any history of dengue infection and living in a dengue hotspot, in Selangor, Malaysia, were dengue IgM and IgG positive respectively. When dengue-positive mosquitoes were detected in the hotspot, 11 (6.3%) of the 174 in iduals tested were found to have dengue viremia, of which 10 were asymptomatic. Besides, upon detection of a dengue-infected mosquito, transmission was already widespread. In a clinical setting, it appears that people living with dengue patients have been exposed to dengue, whether asymptomatic or symptomatic. They can either have circulating viral RNA and/or presence of NS1 antigen. It is also possible that they are dengue seropositive. Collectively, the results indicate that actions taken to control dengue transmission after the first report of dengue cases may be already too late. The current study also revealed challenges in diagnosing clinically inapparent dengue in hyperendemic settings. There is no one best method for diagnosing inapparent dengue. This study demonstrates empirical evidence of inapparent dengue in different settings. Early dengue surveillance in the mosquito population and active serological/virological surveillance in humans can go hand in hand. More studies are required to investigate the epidemiology, seroprevalence, diagnostics, and control of inapparent dengue. It is also crucial to educate the public, health staff and medical professionals on asymptomatic dengue and to propagate awareness, which is important for controlling transmission.
Publisher: Public Library of Science (PLoS)
Date: 02-04-2013
Publisher: eLife Sciences Publications, Ltd
Date: 18-02-2020
DOI: 10.7554/ELIFE.51546
Abstract: In malaria, rosetting is described as a phenomenon where an infected erythrocyte (IRBC) is attached to uninfected erythrocytes (URBC). In some studies, rosetting has been associated with malaria pathogenesis. Here, we have identified a new type of rosetting. Using a step-by-step approach, we identified IGFBP7, a protein secreted by monocytes in response to parasite stimulation, as a rosette-stimulator for Plasmodium falciparum- and P. vivax-IRBC. IGFBP7-mediated rosette-stimulation was rapid yet reversible. Unlike type I rosetting that involves direct interaction of rosetting ligands on IRBC and receptors on URBC, the IGFBP7-mediated, type II rosetting requires two additional serum factors, namely von Willebrand factor and thrombospondin-1. These two factors interact with IGFBP7 to mediate rosette formation by the IRBC. Importantly, the IGFBP7-induced type II rosetting h ers phagocytosis of IRBC by host phagocytes.
Publisher: Springer Science and Business Media LLC
Date: 09-05-2015
Publisher: Proceedings of the National Academy of Sciences
Date: 14-06-2016
Abstract: Plasmodium knowlesi is a parasite that naturally infects cynomolgus monkeys but is also a major cause of severe zoonotic malaria in humans in South East Asia. Comparing the genomes of parasites restricted to growth in culture with cynomolgus RBCs and those adapted to growth in human RBCs identified a gene specifically required for invasion of human RBCs, a process that is critical for parasite replication. This gene encodes normocyte-binding protein Xa, a protein previously shown to bind human RBCs and implicated in invasion. Disruption of this gene blocks invasion of human but not cynomolgus RBCs, thus confirming a key mediator of human infection and a potential target for inclusion in vaccines to prevent human infection.
Publisher: Springer Science and Business Media LLC
Date: 21-04-2016
DOI: 10.1038/SREP24623
Abstract: Plasmodium knowlesi is extensively used as an important malaria model and is now recognized as an important cause of human malaria in Malaysia. The strains of P. knowlesi currently used for research were isolated many decades ago, raising concerns that they might no longer be representative of contemporary parasite populations. We derived a new P. knowlesi line (University Malaya line, UM01), from a patient admitted in Kuala Lumpur, Malaysia, and compared it with a human-adapted laboratory line (A1-H.1) derived from the P. knowlesi H strain. The UM01 and A1-H.1 lines readily invade human and macaque ( Macaca fascicularis ) normocytes with a preference for reticulocytes. Whereas invasion of human red blood cells was dependent on the presence of the Duffy antigen/receptor for chemokines (DARC) for both parasite lines, this was not the case for macaque red blood cells. Nonetheless, differences in invasion efficiency, gametocyte production and the length of the asexual cycle were noted between the two lines. It would be judicious to isolate and characterise numerous P. knowlesi lines for use in future experimental investigations of this zoonotic species.
No related grants have been discovered for Yee Ling Lau.