Occurrence and Distribution of Non-falciparum Malaria Parasite Species among Adolescents and Adults in Malawi.

BACKGROUND Plasmodium falciparum malaria dominates throughout sub-Saharan Africa, but the prevalence of P. malariae, P. ovale spp., and P. vivax increasingly contribute to infection in countries which control malaria using P. falciparum-specific diagnostic and treatment strategies. METHODS We performed qPCR on 2,987 dried blood spots from the 2015-2016 Malawi Demographic and Health Survey to identify the presence and distribution of non-falciparum infection. Bivariate models were used to determine species-specific associations with demographic and environmental risk factors. RESULTS Non-falciparum infections had a broad spatial distribution. Weighted prevalence was 0.025 (SE: 0.004) for P. malariae, 0.097 (SE: 0.008) for P. ovale spp., and 0.001 (SE: 0.0005) for P. vivax. Most infections (85.6%) had low-density parasitemias ≤10 parasites/µL, and 66.7% of P. malariae, 34.6% of P. ovale spp., and 40.0% of P. vivax infections were co-infected with P. falciparum. Risk factors for P. malariae were like those known for P. falciparum, however, there were few risk factors recognized for P. ovale spp. and P. vivax, perhaps due to the potential for relapsing episodes. CONCLUSIONS The prevalence of any non-falciparum infection was 11.7%, with infections distributed across Malawi. Continued monitoring of Plasmodium spp. becomes critical as non-falciparum infections become important sources of ongoing transmission.