Oral Presentation First Malaria World Congress 2018

An inconvenient truth: the rise of knowlesi malaria in the elimination era (#33)

Nick Anstey 1
  1. Menzies School of Health Research, Casuarina, Darwin, NT, Australia

Plasmodium falciparum and P. vivax remain the major causes of malaria morbidity and mortality in the Asia-Pacific, and the elimination agenda rightfully targets these two species. With the success of national malaria control programs in moving toward elimination of these human-only species, a number of countries have seen parallel rises in zoonotic malaria from the monkey parasite, Plasmodium knowlesi. In Sabah, Malaysia, over 2000 cases of knowlesi malaria occurred in 2017, including fatalities, more than double the number seen in 2015, and accounting for over 98% of all malaria. Knowlesi malaria has now been reported in all countries across SE Asia and is now the commonest cause of malaria in Malaysia, a number of districts in western Indonesia and the only malaria occurring in Brunei and Singapore. Despite this, knowlesi incidence is not reported in the World Malaria Report and its incidence in co-endemic countries outside of Malaysia (where molecular surveillance is routine) is likely to be underestimated. With 6-9% of clinical cases being severe, including ongoing fatal cases, its recognition is important for appropriate clinical management. P. knowlesi is microscopically indistinguishable from P. malariae and is also commonly misidentified as P. falciparum and P. vivax in routine microscopy in co-endemic regions: PCR is required for identification. As well as clinical risk, misdiagnosis as falciparum, vivax or malariae malaria underestimates the success of elimination programs for human-only species. More widespread molecular surveillance in knowlesi-endemic countries is needed. While the elimination agenda for human-only species targets elimination of infection, goals for zoonotic malaria should include elimination of disease and death.