Host feeding preferences of malaria vectors in an area of low malaria transmission
Résumé
Studying the behaviour and trophic preferences of mosquitoes is an important step in understanding the exposure of vertebrate hosts to vector-borne diseases. In the case of human malaria, transmission increases when mosquitoes feed more on humans than on other animals. Therefore, understanding the spatio-temporal dynamics of vectors and their feeding preferences is essential for improving vector control measures. In this study, we investigated the feeding behaviour of Anopheles mosquitoes at two sites in the Sudanian areas of Senegal where transmission is low following the implementation of vector control measures. Blood-fed mosquitoes were collected monthly from July to November 2022 by pyrethrum spray catches in sleeping rooms of almost all houses in Dielmo and Ndiop villages, and blood meals were identified as from human, bovine, ovine, equine and chicken by ELISA. Species from the An. gambiae complex were identified by PCR. The types and numbers of potential domestic animal hosts were recorded in each village. The Human Blood Index (HBI) and the Manly Selection Ratio (MSR) were calculated to determine whether hosts were selected in proportion to their abundance. Spatio-temporal variation in HBI was examined using the Moran's index. A total of 1251 endophilic Anopheles females were collected in 115 bedrooms, including 864 blood fed females of 6 species. An. arabiensis and An. funestus were predominant in Dielmo and Ndiop, respectively. Of the 864 blood meals tested, 853 gave a single host positive result mainly on bovine, equine, human, ovine and chicken in decreasing order in both villages. Overall, these hosts were not selected in proportion to their abundance. The human host was under-selected, highlighting a marked zoophily for the vectors. Over time and space, the HBI were low with no obvious trend, with higher and lower values observed in each of the five months at different points in each village. These results highlight the zoophilic and exophagic behaviour of malaria vectors. This behaviour is likely to be a consequence of the distribution and use of LLINs in both villages and may increase risk of residual outdoor transmission. This underlines the need to study the feeding host profile of outdoor resting populations and how domestic animals may influence malaria epidemiology in order to tailor effective malaria vector control strategies in the two villages. To better understand the dynamics of malaria transmission, the identification of blood meal sources of Anopheles vectors is essential to assess the risk of human exposure 1. Of the 500 described Anopheles species, about 60 are responsible for the majority of malaria cases 2,3. In most regions where they occur, An. gambiae, An. arabiensis, An. coluzzii and An. funestus are the most prevalent and most involved in malaria transmission and are therefore, considered the main vectors of malaria in sub-Saharan Africa 4-6. Considered for a long time as highly anthropophilic and endophilic species, several recent papers have highlighted a zoophilic tendency following the implementation of vector control strategies 7-9. Furthermore, known for their crepuscular and nocturnal biting activity, a switch in biting behaviour has been demonstrated at times and places where humans are not protected 10,11. Thus, determining the trophic preferences of vectors and their human blood index are important for understanding their biting behaviour, especially in areas where additional
| Origine | Fichiers éditeurs autorisés sur une archive ouverte |
|---|---|
| licence |
