Exposure and infection to Plasmodium knowlesi in case study communities in Northern Sabah, Malaysia and Palawan, The Philippines

摘要

Author summary Plasmodium knowlesi is a species of malaria parasite found in wild macaque populations which is now the main cause of human malaria in Malaysian Borneo. Spread from macaques to people through infected mosquitoes, human P. knowlesi malaria cases have primarily been reported in adult men working in forests or plantations. However, little data is available on the extent of asymptomatic infections or people exposed to P. knowlesi not reporting to clinics. We conducted comprehensive surveys of three case study communities in Malaysian Borneo and Palawan, the Philippines with varying numbers of P. knowlesi cases reported. In addition to testing for infection, we measured species-specific antibody responses to P. knowlesi and other malaria species to identify exposed individuals. Few asymptomatic infections were detected and varying levels of P. knowlesi exposure was detected between sites. P. knowlesi exposure was identified in both men and women and associated with farm work and forest and clearing around the house. Spatial patterns and risk factors for P. knowlesi differed from other malaria species, highlighting the need for knowlesi specific disease control measures. Results suggest more people are exposed to P. knowlesi than are identified at clinics and exposure to P. knowlesi may occur in different demographic groups and geographic areas than previously reported.