Natural Plasmodium infection in wild macaques of three states in peninsular Malaysia

Zoonotic cases of Plasmodium knowlesi account for most malaria cases in Malaysia, and humans infected with P. cynomolgi, another parasite of macaques have recently been reported in Sarawak. To date the epidemiology of malaria in its natural Macaca reservoir hosts remains little investigated. In this study we surveyed the prevalence of simian malaria in wild macaques of three states in Peninsular Malaysia, namely Pahang, Perak and Johor using blood samples from 103 wild macaques (collected by the Department of Wildlife and National Parks Peninsular Malaysia) subjected to microscopic examination and nested PCR targeting the Plasmodium small subunit ribosomal RNA gene. As expected, PCR analysis yielded significantly higher prevalence (64/103) as compared to microscopic examination (27/103). No relationship between the age and/or sex of the macaques with the parasitaemia and the Plasmodium species infecting the macaques could be identified. Wild macaques in Pahang had the highest prevalence of Plasmodium parasites (89.7%), followed by those of Perak (69.2%) and Johor (28.9%). Plasmodium inui and P. cynomolgi were the two most prevalent species infecting the macaques from all three states. Half of the macaques (33/64) harboured two or more Plasmodium species. These data provide a baseline survey, which should be extended by further longitudinal investigations that should be associated with studies on the bionomics of the anopheline vectors. This information will allow an accurate evaluation of the risk of zoonotic transmission to humans, and to elaborate effective strategies to control simian malaria

The Effects of Temperature on the ABAcard HemaTrace kit for the Identification of Human Blood

Blood is often cited as the most informative form of evidence at a violent crime scene. DNA analysis enables the identification of individuals involved in a crime whilst blood pattern analysis enables the reconstruction of a crime scene. Prior to analysis, potential bloodstains found at a crime scene are processed via observation, documentation, followed by presumptive testing. This screening process eliminates substances that have a similar appearance to human blood therefore ensuring that time and resources are not wasted on samples with little or no forensic value. The ABACard® HemaTrace® kit is a lateral flow immunochromatographic assay that targets human haemoglobin using antibodies and is used by the Western Australia (WA) Police as a test for the identification of human blood. However, WA Police officers have noted that in the northern regions of Western Australia, HemaTrace® kits have resulted in false negatives. It was postulated that this is due to prolonged exposure of the HemaTrace® kits to elevated storage temperatures resulting in a decrease in the HemaTrace® kit sensitivity and efficacy. However, a temperature stress test on HemaTrace has yet to be reported in the scientific literature and thus this hypothesis remains inconclusive. Thus, this literature review aims to critically assess the current literature pertaining to the HemaTrace® kits with emphasis on the sensitivity, specificity and robustness of the kits. As there are currently no studies that have investigated the effects of temperature on the performance of ABACard® HemaTrace® kit, this literature review will explore temperature studies on antibodies and other lateral flow immunochromatographic assays in order to postulate the effects of temperature on the HemaTrace® kits. Lastly, this literature review will outline parameters for potential research in order to evaluate whether elevated temperature exposure for prolonged periods is potentially responsible for the HemaTrace® false negatives obtained in northern WA

Molecular evidence of Sarcocystis nesbitti in water samples of Tioman Island, Malaysia

Abstract Background Sarcocystis are intracellular protozoan parasites that are characterised by their ability to invade muscle tissue and form intramuscular sarcocysts. A muscular sarcocystosis outbreak was reported by travellers returning from Tioman Island in 2011 and 2012 where Sarcocystis nesbitti was identified as the main cause. The source of the S. nesbitti that was involved has remained elusive, although water is hypothesised to be the main cause of transmission. A surveillance study was therefore undertaken in the northern regions of Tioman Island to identify the source of S. nesbitti by screening rivers, water tanks, wells and seawater. Methods Water samples were collected from rivers, water tanks, wells and seawater on Tioman Island over the course of April to October 2015. Water samples were indirectly screened for Sarcocystis species by obtaining sediment from respective water sources. PCR amplification of the 18S rRNA gene region was conducted to identify positive samples. Microscopy was used in an attempt to reappraise PCR results, but no sporocysts were detected in any of the samples. Results A total of 157 water samples were obtained and 19 were positive for various Sarcocystis species. Through BLASTn and phylogenetic analysis, these species were found to be S. singaporensis, S. nesbitti, Sarcocystis sp. YLL-2013 and one unidentified Sarcocystis species. Conclusions This is the first positive finding of S. nesbitti in water samples on Tioman Island, which was found in a water tank and in river water samples. This finding supports the hypothesis that water was a potential medium for the transmission of S. nesbitti during the outbreak. This will potentially identify areas in which preventive measures can be taken to prevent future outbreaks

Cytoadherence properties of Plasmodium knowlesi-infected erythrocytes

Plasmodium knowlesi is responsible for zoonotic malaria infections that are potentially fatal. While the severe pathology of falciparum malaria is associated with cytoadherence phenomena by Plasmodium falciparum-infected erythrocytes (IRBC), information regarding cytoadherence properties of P. knowlesi-IRBC remained scarce. Here, we characterized the cytoadherence properties of RBC infected with the laboratory-adapted P. knowlesi A1-H.1 strain. We found that late-stage IRBC formed rosettes in a human serum-dependent manner, and rosettes hampered IRBC phagocytosis. IRBC did not adhere much to unexposed (unstimulated) human endothelial cell lines derived from the brain (hCMEC/D3), lungs (HPMEC), and kidneys (HRGEC). However, after being "primed" with P. knowlesi culture supernatant, the IRBC-endothelial cytoadherence rate increased in HPMEC and HRGEC, but not in hCMEC/D3 cells. Both endothelial cytoadherence and rosetting phenomena were abrogated by treatment of P. knowlesi-IRBC with trypsin. We also found that different receptors were involved in IRBC cytoadherence to different types of endothelial cells. Although some of the host receptors were shared by both P. falciparum- and P. knowlesi-IRBC, the availability of glycoconjugates on the receptors might influence the capacity of P. knowlesi-IRBC to cytoadhere to these receptors.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)Published versionW-CL, SN, and LR were supported by core funding from A ∗ STAR. W-CL was funded by the Open Fund-Young Individual Research Grant (OF-YIRG NMRC/OFYIRG/0070/2018). LR was funded by A∗ STAR grant (JCO-DP BMSI/15-800006-SIGN) and Singapore Ministry of Education AcRF Tier 3 grant (MOE2019- T3-1-007). SN was also supported by a postgraduate scholarship from the Yong Loo Lin School of Medicine, NUS

Molecular Evidence of Sarcocystis Species Infecting Reptiles in Peninsular Malaysia

Background: The genus Sarcocystis consists of intracellular coccidian protozoan parasites with the ability to invade muscle tissue and mature into sarcocysts, causing the zoonotic disease sarcocystosis. These parasites have an obligatory two-host life cycle, which correlates with prey-predator relationship. The distribution and prevalence of Sarcocystis in reptiles remains unclear, despite several previous reports. The aim of this study was to identify the genetic assemblage of the species of Sarcocystis infecting Malaysian snakes and lizards by screening stool samples. Methods: Overall, 54 fecal samples of various snake species and four fecal samples of several lizard species in Malaysia were taken within the course of August 2015 to January 2016 from Seremban, Melaka, Tioman Island, Pahang, Klang and Langkawi Wildlife Park located in Malaysia. The samples were examined for Sarcocystis through PCR amplification of the 18S rDNA sequence at the Department of Parasitology, University of Malaya Results: Fourteen snake fecal samples were positive via PCR; however, only eight samples (14%) were found positive for Sarcocystis species, whereas four were positive for other genera and the identity of another three samples was unable to be determined. Further phylogenetic analysis of the 18S rDNA sequences revealed that the snakes were infected with either S. singaporensis, S. lacertae, or undefined Sarcocystis species closely related to either S. singaporensis or S. zuoi. Sarcocystis nesbitti infection was not identified in any of the infected snakes. Conclusion: This is the first report of identification of S. lacertae in the black-headed cat snake. © 2019, Tehran University of Medical Sciences (TUMS). All rights reserved

The prevalence of simian malaria in wild long-tailed macaques throughout Peninsular Malaysia

Abstract The parasite Plasmodium knowlesi has been the sole cause of malaria in Malaysia from 2018 to 2022. The persistence of this zoonotic species has hampered Malaysia’s progress towards achieving the malaria-free status awarded by the World Health Organisation (WHO). Due to the zoonotic nature of P. knowlesi infections, it is important to study the prevalence of the parasite in the macaque host, the long-tailed macaque (Macaca fascicularis). Apart from P. knowlesi, the long-tailed macaque is also able to harbour Plasmodium cynomolgi, Plasmodium inui, Plasmodium caotneyi and Plasmodium fieldi. Here we report the prevalence of the 5 simian malaria parasites in the wild long-tailed macaque population in 12 out of the 13 states in Peninsular Malaysia using a nested PCR approach targeting the 18s ribosomal RNA (18s rRNA) gene. It was found that all five Plasmodium species were widely distributed throughout Peninsular Malaysia except for states with major cities such as Kuala Lumpur and Putrajaya. Of note, Pahang reported a malaria prevalence of 100% in the long-tailed macaque population, identifying it as a potential hotspot for zoonotic transmission. Overall, this study shows the distribution of the 5 simian malaria parasite species throughout Peninsular Malaysia, the data of which could be used to guide future malaria control interventions to target zoonotic malaria

Natural Plasmodium infection in wild macaques of three states in peninsular Malaysia

International audienceZoonotic cases of Plasmodium knowlesi account for most malaria cases in Malaysia, and humans infected with P. cynomolgi, another parasite of macaques have recently been reported in Sarawak. To date the epidemiology of malaria in its natural Macaca reservoir hosts remains little investigated. In this study we surveyed the prevalence of simian malaria in wild macaques of three states in Peninsular Malaysia, namely Pahang, Perak and Johor using blood samples from 103 wild macaques (collected by the Department of Wildlife and National Parks Peninsular Malaysia) subjected to microscopic examination and nested PCR targeting the Plasmodium small subunit ribosomal RNA gene. As expected, PCR analysis yielded significantly higher prevalence (64/103) as compared to microscopic examination (27/103). No relationship between the age and/or sex of the macaques with the parasitaemia and the Plasmodium species infecting the macaques could be identified. Wild macaques in Pahang had the highest prevalence of Plasmodium parasites (89.7%), followed by those of Perak (69.2%) and Johor (28.9%). Plasmodium inui and P. cynomolgi were the two most prevalent species infecting the macaques from all three states. Half of the macaques (33/64) harboured two or more Plasmodium species. These data provide a baseline survey, which should be extended by further longitudinal investigations that should be associated with studies on the bionomics of the anopheline vectors. This information will allow an accurate evaluation of the risk of zoonotic transmission to humans, and to elaborate effective strategies to control simian malaria