November 20, 2015
Current status of evidence about Plasmodium vivax transmission in Africa
Howes et al published 'Plasmodium vivax transmission in Africa', in Public Library of Science Neglected Tropical Diseases, which reviews the current status of evidence about Plasmodium vivax transmission in Africa.
Plasmodium vivax (Pv) is the most widely distributed malaria parasite globally, but conspicuously “absent” from Africa. The majority of African populations do not express the Duffy blood group antigen, which is the only known receptor for Pv infection. Since this discovery in the 1970s, the low clinical incidence of Pv in Africa has resulted in a perception of Pv being completely absent and any apparent cases being misdiagnoses, and no public health allowances are made for this parasite in terms of diagnosis, treatment or surveillance reporting.As more sensitive diagnostics become available, Pv infection in Africa is increasingly reported from a variety of different survey types: entomological, serological, community prevalence surveys, as well as clinical infection data from local residents and travellers returning to malaria-free countries.
A literature review was conducted to assemble these reports and assess the current status of evidence about Pv transmission in Africa. Moderate to conclusive evidence of transmission was available from 18 of the 47 malariaendemic countries examined, distributed across all parts of the continent. Mechanisms explaining this reported transmission are evaluated, as well as alternative explanations for the observations. Combinations of complementary explanations are likely, varying according to regional ecology and population characteristics. The public health implications of these observations and recommendations for increased awareness of Pv transmission on this continent are discussed.