Asymptomatic Plasmodium falciparum Infection Was Not Associated with Exposure to Soil-Transmitted Helminths in...

Asymptomatic carriage of Plasmodium falciparum is a major public health threat hindering malaria eradication. Many areas with ongoing malaria transmission are coendemic for soil-transmitted helminths (STHs). Proteins secreted by helminths can regulate host inflammatory immune responses as a survival strategy. Given that malaria is a disease mediated by inflammation, we tested the hypothesis that STH infection and/or exposure might be associated with asymptomatic Plasmodium infection. We performed a 1-month longitudinal study of 134 primary school children across three school-based study sites in Esse, Centre Region, Cameroon. At our initial screening time point, 94.8% of children were microscopy positive for P. falciparum infection, and 85.8% had asymptomatic microscopic P. falciparum infection. A total of 87.4% of children had serologic positivity for at least one STH recombinant antigen. Comparing children with asymptomatic P. falciparum infection and uncomplicated symptomatic malaria at baseline, we found no significant difference in the percentage of children with STH exposure (85.7% versus 90.9%, P >0.05). Daily temperature checks were performed over the course of 1 month to assess whether children with asymptomatic P. falciparum infection developed uncomplicated symptomatic malaria. Of the children who experienced fever, the development of fever was associated with increased reactivity to STH antigens. No correlation was found between anti-STH antibody level and P. falciparum load (P >0.05), and no association was observed between STH exposure and persistent asymptomatic P. falciparum infection. These data suggest that STH exposure is not a major factor that contributes to the asymptomatic carriage of P. falciparum in children.