Defining the Geographical Range of the Plasmodium knowlesi Reservoir

Abstract

BackgroundThe simian malaria parasite, Plasmodium knowlesi, can cause severe and fatal disease in humans yet it is rarely included in routine public health reporting systems for malaria and its geographical range is largely unknown. Because malaria caused by P. knowlesi is a truly neglected tropical disease, there are substantial obstacles to defining the geographical extent and risk of this disease. Information is required on the occurrence of human cases in different locations, on which non-human primates host this parasite and on which vectors are able to transmit it to humans. We undertook a systematic review and ranked the existing evidence, at a subnational spatial scale, to investigate the potential geographical range of the parasite reservoir capable of infecting humans.Methodology/Principal FindingsAfter reviewing the published literature we identified potential host and vector species and ranked these based on how informative they are for the presence of an infectious parasite reservoir, based on current evidence. We collated spatial data on parasite occurrence and the ranges of the identified host and vector species. The ranked spatial data allowed us to assign an evidence score to 475 subnational areas in 19 countries and we present the results on a map of the Southeast and South Asia region.Conclusions/SignificanceWe have ranked subnational areas within the potential disease range according to evidence for presence of a disease risk to humans, providing geographical evidence to support decisions on prevention, management and prophylaxis. This work also highlights the unknown risk status of large parts of the region. Within this unknown category, our map identifies which areas have most evidence for the potential to support an infectious reservoir and are therefore a priority for further investigation. Furthermore we identify geographical areas where further investigation of putative host and vector species would be highly informative for the region-wide assessment.

Malaria diagnosis for malaria elimination

“…(4) Variable numbers of merozoites are present in iRBCs [36][37][38]. (5) P. falciparum and P. vivax are often coendemic globally [39,40], whereas P. knowlesi is a zoonotic infection of humans and macaques in Southeast Asia [41]. Although travelers have become infected there are no reports of human-to-human transmission beyond this region [42 & ].…”

A Review of Plasmodium knowlesi among Macaques in Malaysia

“…The increase in number of identified cases is due to the availability of better diagnostic tools and the increase in transmission of P. knowlesi from macaques host to humans via mosquitoes (Divis et al, 2015). Its symptoms among humans may be found similar to other malaria parasites (Moyes et al, 2014).…”

„Affenmalaria“ nach Thailandreise

“…Verzögerte Diagnose und Therapie sind erwartungsgemäß ein Risiko für schwere Verlaufsformen [10,12,20]. Allerdings hatten 2 der deutschen Patienten, wie auch Patienten einer prospektiven indonesischen Studie [20] [9,10]. In einigen Gebieten Malaysias wurden mittels PCR-Diagnostik hohe und in den letzten Jahren zunehmende Prävalenzen beim Menschen gefunden.…”