High Prevalence of Gametocyte Carriage among Individuals with Asymptomatic Malaria: Implications for Sustaining Malaria Control and Elimination Efforts in Ethiopia

Asymptomatic malaria often contributes to the reservoir of infection in disease transmission. This study reports the prevalence of gametocyte carriage among asymptomatic individuals and assesses the risk factors associated with asymptomatic malaria in the suburbs of Jimma town, southwestern Ethiopia. A cohort of 582 individuals residing in the suburbs of Jimma town was followed up for three months from September 2013 to November 2013. A total of 1,746 blood films were collected using active case detection. Sociodemographic profile of the study participants was collected using a pretested semistructured questionnaire. The incidence of asymptomatic Plasmodium falciparum malaria was 17.18/1,000 person-months at risk, and for Plasmodium vivax, it was 17.8/1,000 person-months at risk. The gametocyte carriage rates of P. falciparum and P. vivax were 66.7% and 12.9% among asymptomatic P. falciparum- and P. vivax-infected individuals, respectively. Geometric mean gametocyte and asexual parasite density among asymptomatic malaria cases were 412.66 (interquartile range [IQR], 300–660) and 1,866.61 (IQR, 900–6,540) parasites/μL, respectively. Age, place of residence, and distance from vector-breeding site were the main predictors of asymptomatic malaria. The high gametocyte carriage among individuals with asymptomatic malaria in the study area calls for screening and treatment of asymptomatic carriers to interrupt transmission and enhance malaria elimination efforts.