Risk factors for malaria infection in central Madagascar: insights from a cross-sectional population survey

Journal article

Community prevalence of infection is a widely used, standardized metric for evaluating malaria endemicity. Conventional methods for measuring prevalence include light microscopy and rapid diagnostic tests (RDT), but their detection thresholds are inadequate for diagnosing low density infections. The significance of sub-microscopic malaria infections is poorly understood in Madagascar, a country of heterogeneous malaria epidemiology. A cross-sectional community survey in the western foothills of Madagascar during the March 2014 transmission season found malaria infection to be predominantly sub-microscopic and asymptomatic. Prevalence of Plasmodium infection diagnosed by microscopy, RDT, and molecular diagnosis was 2.4%, 4.1% and 13.8%, respectively. This diagnostic discordance was greatest for Plasmodium vivax infection, which was 98.5% sub-microscopic. Village location, ITN ownership and fever were significantly associated with infection outcomes, as was presence of another infected individual in the household. Duffy negative individuals were diagnosed with P. vivax, but with reduced odds relative to Duffy positive hosts. The observation of high proportions of sub-microscopic infections calls for a wider assessment of the parasite reservoir in other regions of the island, particularly given the country’s current focus on malaria elimination and the poorly documented distribution of the non-P. falciparum parasite species.

Authors: Howes, R; Franchard, T; Rakotomanga, A; Ramiranirina, B; Zikursh, M

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Society of Tropical Medicine and Hygiene
• Journal: American Journal of Tropical Medicine and Hygiene
• Volume: 99
• Issue: 4
• Pages: 995-1002
• Publication date: 2018-09-04
• Acceptance date: 2018-07-20
• DOI: 10.4269/ajtmh.18-0417
• EISSN: 1476-1645
• ISSN: 0002-9637
• Keywords: Madagascar; malaria; diagnostics; Duffy blood group; sub-microscopic infection