Seroprevalence and Parasite Rates of Plasmodium malariae in a High Malaria Transmission Setting of Southern Nigeria

Although continues to be the main target for malaria elimination, other species persist in Africa. Their clinical diagnosis is uncommon, whereas rapid diagnostic tests (RDTs), the most widely used malaria diagnostic tools, are only able to distinguish between and non- species, the latter as "pan-species." Blood samples from health facilities were collected in southern Nigeria (Lagos and Calabar) in 2017 (October-December) and Calabar only in 2018 (October-November), and analyzed by several methods, namely, microscopy, quantitative real-time PCR (qPCR), and peptide serology targeting candidate antigens ( apical membrane antigen, . lactose dehydrogenase, and . circumsporozoite surface protein). Both microscopy and qPCR diagnostic approaches detected comparable proportions (∼80%) of all RDT-positive samples infected with the dominant malaria parasite. However, higher proportions of non- species were detected by qPCR than microscopy, 10% against 3% infections for and 3% against 0% for , respectively. No infection was detected. Infection rates for varied between age-groups, with the highest rates in individuals aged > 5 years. -specific seroprevalence rates fluctuated in those aged < 10 years but generally reached the peak around 20 years of age for all peptides. The heterogeneity and rates of these non-falciparum species call for increased specific diagnosis and targeting by elimination strategies.