Modelling RVF vector population dynamics in a tropical setting in South-Eastern Madagascar

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Chevalier, Laure, J. G. | Chevalier, Véronique | Balenghien, Thomas | Durand, Benoit | Tantely, Michaël Luciano | Ezanno, Pauline

Edité par CCSD -

International audience. Introduction and Objectives : Rift valley fever (RVF) is an emerging zoonotic arbovirosis circulating in Africa, the Middle East and the Indian Ocean. It has been identified by the WHO as a priority disease for research, surveillance and prevention, due to the high human, animal and economic toll it has on affected communities. Three large epizootic waves have hit Madagascar since RVF virus (RVFV) was introduced there, including in 2021 in South-Eastern Madagascar. Interepizootic circulation has been demonstrated. We studied the population dynamics of two suspected RVFV vector species in South-Eastern Madagascar: Anopheles coustani and Culex antennatus. The outputs will be used to model RVFV transmission, and ultimately allow for risk assessment of RVF flares according to climate variables.Materials and Methods : A generic mechanistic compartmental model, representing mosquito life cycle and driven by temperature and rainfall, was adapted to each of the two vector species. We used the model to estimate the relative abundances of host-seeking mosquitoes over time, which we then compared to observed mosquito captures.Results, Discussion and Conclusion : Our model was able to predict vector population dynamics according to climate variables, with predictions in good agreement with field observations, especially for Anopheles coustani. Peaks in predicted mosquito abundance occurred at the end of the wet season, which is concurrent to a high RVFV circulation. These first results are promising when it comes to incorporating the population dynamic model into a transmission model for RVFV in Madagascar.

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