Plasmodium falciparum infection in humans and mosquitoes influence natural Anopheline biting behavior and transmission

The human infectious reservoir of Plasmodium falciparum is governed by transmission efficiency during vector–human contact and mosquito biting preferences. In a 15‑month cohort in western Kenya, we detected P. falciparum in indoor‑resting Anopheles and human blood samples by qPCR and matched mosquito bloodmeals to cohort participants using short‑tandem repeat genotyping. Using risk factor analysis and discrete choice models, we assessed mosquito biting behavior with respect to parasite transmission. Biting was highly unequal; 20% of people received 86% of bites. Biting rates were higher on males (biting rate ratio [BRR]: 1.68; 95% CI: 1.28–2.19), children 5–15 years (BRR: 1.49; 95% CI: 1.13–1.98), and P. falciparum‑infected individuals (BRR: 1.25; 95% CI: 1.01–1.56). In aggregate, P. falciparum‑infected school‑age boys accounted for 50% of bites potentially leading to onward transmission and had an entomological inoculation rate 6.4× higher than any other group. Infectious mosquitoes were nearly 3× more likely than non‑infectious mosquitoes to bite P. falciparum‑infected individuals (relative risk ratio 2.76, 95% CI: 1.65–4.61). Persistent transmission was characterized by disproportionate onward transmission from school‑age boys and by the preference of infected mosquitoes to feed upon infected people.

Christine F. Markwalter, Zena Lapp, Lucy Abel, Emmah Kimachas, Evans Omollo, Elizabeth Freedman, Tabitha Chepkony, Mark Amunga, Tyler McCormick, Sophie Bérubé, Judith N. Mangeni, Amy Wesolowski, Andrew A. Obala, Steve M. Taylor, Wendy Prudhomme O'Meara