Frontiers in Public Health (Aug 2014)
Zoonotic Malaria – Global Overview and Research and Policy Needs
Abstract
The four main Plasmodium species that cause human malaria, P. falciparum, P. vivax, P. malaria and P. ovale, are transmitted between humans by mosquito vectors belonging to the genus Anopheles. It has recently become evident that P. knowlesi, a parasite that typically infects forest macaque monkeys, can be transmitted by anophelines to cause malaria in humans in Southeast Asia. Plasmodium knowlesi infections are frequently misdiagnosed microscopically as P. malariae. Direct human to human transmission of P. knowlesi by anophelines has not yet been established to occur in nature. Knowlesi malaria must therefore be presently considered a zoonotic disease. PCR is now the definitive method for differentiating P. knowlesi from P. malariae and other human malaria parasites. The origin of P. falciparum and P. vivax in African apes are examples of ancient zoonoses that may be continuing at the present time with at least P. vivax, and possibly P. ovale and P. malariae. Other primate malaria species e.g. P. cynomolgi in Southeast Asia and P. brasilianum and P. simium in South America, can be naturally transmitted to humans further emphasising the potential for continuing zoonoses. The potential for zoonosis is influenced by human habitation and behaviour as well the adaptive capabilities of parasites and vectors. There is insufficient knowledge of the bionomics of Anopheles vector populations relevant to the cross-species transfer of malaria parasites and the real extent of malaria zoonoses. Appropriate strategies, based on more research, need to be developed for the prevention, diagnosis and treatment of zoonotic malaria.
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