Influence of the dry and humid seasons on the assessment of human exposure to malaria vector bites in Bobo-Dioulasso, Burkina Faso

---

Résumé

Residual malaria transmission in urban Bobo-Dioulasso persists due to mosquito adaptations. This study examines the ecological and behavioral factors sustaining transmission, based on seasonal Anopheles collections
along riverbanks using residual fauna and human landing catch methods from 2023 to 2024. Our study aimed to
assess human exposure to malaria vector bites in Bobo-Dioulasso. Entomological collections, including Human
Landing Catches (HLC) and Pyrethrum Spray Catches (PSC), were conducted during the study. A total of 1455
mosquitoes were cotocluding 922 through Human Landing Catches (HLC) and 533 through Pyrethrum Spray
Catches (PSC), enabling the analysis of (i) species composition within the Anopheles gambiae complex, (ii) the
detection of Plasmodium infections, and (iii) the identification of blood meal sources to assess the trophic preferences of vectors across seasons. As result, three species of the An. gambiae complex were identified: An.
arabiensis (91.20 %), An. coluzzii (5.09 %), and An. gambiae (3.71 %), with the latter absent during the dry
season. Plasmodium falciparum infections were detected year-round, with 0.16 % of mosquitoes carrying dual
infections (Plasmodium falciparum and Plasmodium malariae) in July. Blood meal analysis revealed predominantly mixed feeding (59.63 %), followed by zoophilic (24.41 %) and anthropophilic (15.96 %) behaviors,
highlighting high trophic plasticity. In urban Bobo-Dioulasso, malaria transmission remains persistent due to the
ecological flexibility of vector species like An. coluzzii, with Entomological Inoculation Rates rising during the
humid season. The continuous presence of infected mosquitoes and their diverse feeding behavior underscores
the need for locally adapted, targeted interventions to effectively address residual transmission.

Mots-clés

Malaria Anopheles s.l., Plasmodium, Residual transmission, Bobo-Dioulasso