SUBMICROSCOPIC EVIDENCE OF THE SIMIAN MALARIA PARASITE, PLASMODIUM KNOWLESI, IN AN ORANG ASLI COMMUNITY

Malaria continues to be a public health burden in Malaysia especially in the interior areas, which are largely populated by the hinterland Orang Asli (OA) community, which constitutes only 0.6% of the total population in Malaysia. Since the re-emergence of Plasmodium knowlesi in the rural area of Malaysian Borneo, reports on the incidence of P. knowlesi cases among the OAs is scarce. Hence, the aim of this current study is to determine the presence of the knowlesi malaria among the asymptomatic aborigine population of Malaysia. The study was conducted on a representative of samples of 306 Orang Asli. Microscopic examination was carried out on all samples. DNA was extracted from dried bloodspots on filter paper and then characterized with nested PCR assay to detect the presence of human malaria parasites and Plasmodium knowlesi. Of these 306 samples that were tested, 193 (63%) were negative for malaria parasites by PCR, whereas another 37 (12%), 23 (8%), 12 (4%), and 10 (3%) were found positive for P. vivax, P. knowlesi, P. falciparum and P. malariae, respectively. Thirty-one (10%) samples were of mixed infection, including 13 (42%) that were multiple infections of human malaria species and P. knowlesi; while another 18 (58%) were multiple infections due to human malaria species. Sequencing of the partial SSUrRNA gene was carried out on all P. knowlesi samples. The OAs were observed to be a healthy population despite presence of malaria infections. More studies should be carried out to determine burden of knowlesi malaria added to the existing human malaria infections.