Malaria Parasites In Macaques In Thailand: Stump-Tailed Macaques (Macaca Arctoides) Are New Natural Hosts Forplasmodium Knowlesi,Plasmodium Inui, Plasmodium Coatneyiandplasmodium Fieldi

Background Certain species of macaques are natural hosts ofPlasmodium knowlesiandPlasmodium cynomolgi, which can both cause malaria in humans, andPlasmodium inui,which can be experimentally transmitted to humans. A significant number of zoonotic malaria cases have been reported in humans throughout Southeast Asia, including Thailand. There have been only two studies undertaken in Thailand to identify malaria parasites in non-human primates in 6 provinces. The objective of this study was to determine the prevalence ofP. knowlesi, P. cynomolgi, P. inui, Plasmodium coatneyiandPlasmodium fieldiin non-human primates from 4 new locations in Thailand. Methods A total of 93 blood samples fromMacaca fascicularis,Macaca leoninaandMacaca arctoideswere collected from four locations in Thailand: 32 were captiveM. fascicularisfrom Chachoengsao Province (CHA), 4 were wildM. fascicularisfrom Ranong Province (RAN), 32 were wildM. arctoidesfrom Prachuap Kiri Khan Province (PRA), and 25 were wildM. leoninafrom Nakornratchasima Province (NAK). DNA was extracted from these samples and analysed by nested PCR assays to detectPlasmodium,and subsequently to detectP. knowlesi, P. coatneyi,P. cynomolgi, P. inuiandP. fieldi. Results Twenty-seven of the 93 (29%) samples werePlasmodium-positive by nested PCR assays. Among wild macaques, all 4 M. fascicularisat RAN were infected with malaria parasites followed by 50% of 32 M. arctoidesat PRA and 20% of 25 M. leoninaat NAK. Only 2 (6.3%) of the 32 captiveM. fascicularisat CHA were malaria-positive. All 5 species ofPlasmodiumwere detected and 16 (59.3%) of the 27 macaques had single infections, 9 had double and 2 had triple infections. The composition ofPlasmodiumspecies in macaques at each sampling site was different.Macaca arctoidesfrom PRA were infected withP. knowlesi, P. coatneyi,P. cynomolgi, P. inuiandP. fieldi. Conclusions The prevalence and species ofPlasmodiumvaried among the wild and captive macaques, and between macaques at 4 sampling sites in Thailand.Macaca arctoidesis a new natural host forP. knowlesi, P. inui, P. coatneyiandP. fieldi.