Abstract:
The human infectious reservoir of Plasmodium falciparum is governed by
transmission efficiency during vector-human contact and mosquito biting
preferences. Understanding biting bias in a natural setting can help target
interventions to interrupt transmission. 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 analyses 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; CI:
1.28–2.19), children 5–15 years (BRR: 1.49; CI: 1.13–1.98), and P. falciparuminfected individuals (BRR: 1.25; CI: 1.01–1.55). In aggregate, P. falciparuminfected school-age (5–15 years) boys accounted for 50% of bites potentially
leading to onward transmission and had an entomological inoculation rate
6.4x higher than any other group. Additionally, infectious mosquitoes were
nearly 3x more likely than non-infectious mosquitoes to bite P. falciparuminfected individuals (relative risk ratio 2.76, 95% CI 1.65–4.61). Thus, persistent
P. falciparum transmission was characterized by disproportionate onward
transmission from school-age boys and by the preference of infected mosquitoes to feed upon infected people.
