Asymptomatic P. falciparum Infection is Not Associated with Exposure to Soil Transmitted Helminths in Children from a Multi School-Based Study in Esse, Cameroon

Asymptomatic carriage of Plasmodium falciparum is a major public health threat hindering malaria eradication. Many areas with ongoing malaria transmission are co-endemic for soil transmitted helminths (STH). 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 an asymptomatic phenotype of Plasmodium infection. We performed a one-month longitudinal study of 134 primary school children across 3 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 malaria and uncomplicated symptomatic malaria at baseline, we found no significant difference in the percentage of children with STH exposure (85.7% vs 90.9%, p >0.05). Daily temperature checks were performed over the course of one month to assess whether children with asymptomatic malaria developed uncomplicated symptomatic malaria. Of the children that developed uncomplicated malaria, 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. This data suggests that STH exposure is not a major factor that contributes to the asymptomatic carriage of P. falciparum in children.