Identification of malaria parasite among macaques in central and South Kalimantan Provinces, Indonesia

Human invasion in the forest domain results in close contact between humans and macaques which may increase the potential transmission of zoonotic diseases, including malaria. Primate-to-human cross-species transmission of infectious agents has become a focus of significant scientific interest over the years. This present study aims to identify malaria parasites among macaques in Central and South Kalimantan Provinces, Indonesia. Whole blood of macaques was served as sample and collected from macaques in four sites (Pulang Pisau and Palangkaraya in Central Kalimantan, Tanah Laut and Banjar in South Kalimantan). Malaria parasite species identification was conducted by using microscopy gold standard assessment and Nested Polymerase Chain Reaction (Nested PCR) using specific primer sets against Plasmodium knowlesi, Plasmodium cynomolgi, and Plasmodium inui. A total of 224 macaques had successfully been trapped, of these 215 (96%) were Macaca fascicularis and 9 (4%) were Macaca nemestrina. Out of 224 whole blood samples tested, 49% were Plasmodium positive, with P. inui (57.3%), P. cynomolgi (16.3%), and P. knowlesi (9.9%), both single or mixed infections. With the increasing of humans and macaques contact being reported in Indonesia, particularly in Kalimantan Provinces as a result of deforestation, the cross-species transmission of malaria becomes a significant health issue to be considered. Moreover, discovering many cases of Plasmodium positive macaques in Kalimantan also increases the potential transmission to humans due to contact between both species. Consequently, appropriate malaria excellent surveillance and diagnostic capacity should be significantly improved to support malaria elimination strategy.