Spatial modeling of risk factors for human exposure to West Nile virus in rural Madagascar
- 1IRD: Institut de recherche pour le developpement
Abstract
BackgroundWest Nile virus (WNV) is an emerging disease transmitted from bird hosts to humans by Culex mosquitoes. Thousands of human cases of WNV infection are reported each year in the United States and Europe, and circulation has been confirmed in Africa and the Indian Ocean, including Madagascar. However, little is known about the current riskscape for people in Madagascar, and what determines its local distribution and human exposure across the population. The goal of this study was to assess WNV seroprevalence and identify associated socio-ecological risk factors in rural Madagascar.
Methodology and principal findingsA cross-sectional serological survey was conducted in Ifanadiana District in 2021, nested within a representative longitudinal cohort. We evaluated serological responses to WNV in 3,948 individuals using a multiplex bead assay. We estimated WNV seroprevalence using a Gaussian Mixture Model (GMM) and characterized environmental, socioeconomic, and demographic factors that could be associated with exposure to WNV using various data sources, including optical and Synthetic Aperture Radar (SAR) satellite images, climate variables, and household survey data. Overall seroprevalence was 43%, and populations living in geographically isolated areas and those engaged in agricultural activities were at higher risk, while proximity to dense forests and residential areas were protective against WNV exposure.
ConclusionsThis study found high rates and local heterogeneity in WNV exposure in a rural district of Madagascar. In addition, environmental, climatic, and socio-demographic data were determinants of WNV transmission, providing a valuable tool for surveillance and decision-making in arbovirus prevention and control. Extending this approach to other orthoflaviviruses could improve understanding of local viral co-circulation and promote the development of more precise and context-specific prevention strategies.
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BibTeX
@misc{randriamihaja2026spatial,
title = {{Spatial modeling of risk factors for human exposure to West Nile virus in rural Madagascar}},
author = {M. Randriamihaja and L. T. Rasoloharimanana and S. Veeragandham and A. C. Miller and K. E. Finnegan and S. Bos and B. Razafinjato and E. Mitsinjoniala and J. A. Kotchofa and P. Garneret and H. L. Razanadranaivo and F. A. Ihantamalala and R. J. L. Rakotonanahary and V. Chevalier and M. H. Bonds and M. Schoenhals and M. V. Evans and S. J. Popper and A. Garchitorena},
howpublished = {medRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.19.26364157},
url = {https://www.medrxiv.org/content/10.64898/2026.10.19.26364157v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Spatial modeling of risk factors for human exposure to West Nile virus in rural Madagascar
AU - M. Randriamihaja
AU - L. T. Rasoloharimanana
AU - S. Veeragandham
AU - A. C. Miller
AU - K. E. Finnegan
AU - S. Bos
AU - B. Razafinjato
AU - E. Mitsinjoniala
AU - J. A. Kotchofa
AU - P. Garneret
AU - H. L. Razanadranaivo
AU - F. A. Ihantamalala
AU - R. J. L. Rakotonanahary
AU - V. Chevalier
AU - M. H. Bonds
AU - M. Schoenhals
AU - M. V. Evans
AU - S. J. Popper
AU - A. Garchitorena
PY - 2026
DA - 2026/10/19
PB - medRxiv
DO - 10.64898/2026.10.19.26364157
UR - https://www.medrxiv.org/content/10.64898/2026.10.19.26364157v1
AB - BackgroundWest Nile virus (WNV) is an emerging disease transmitted from bird hosts to humans by Culex mosquitoes. Thousands of human cases of WNV infection are reported each year in the United States and Europe, and circulation has been confirmed in Africa and the Indian Ocean, including Madagascar. However, little is known about the current riskscape for people in Madagascar, and what determines its local distribution and human exposure across the population. The goal of this study was to assess WNV seroprevalence and identify associated socio-ecological risk factors in rural Madagascar. Methodology and principal findingsA cross-sectional serological survey was conducted in Ifanadiana District in 2021, nested within a representative longitudinal cohort. We evaluated serological responses to WNV in 3,948 individuals using a multiplex bead assay. We estimated WNV seroprevalence using a Gaussian Mixture Model (GMM) and characterized environmental, socioeconomic, and demographic factors that could be associated with exposure to WNV using various data sources, including optical and Synthetic Aperture Radar (SAR) satellite images, climate variables, and household survey data. Overall seroprevalence was 43%, and populations living in geographically isolated areas and those engaged in agricultural activities were at higher risk, while proximity to dense forests and residential areas were protective against WNV exposure. ConclusionsThis study found high rates and local heterogeneity in WNV exposure in a rural district of Madagascar. In addition, environmental, climatic, and socio-demographic data were determinants of WNV transmission, providing a valuable tool for surveillance and decision-making in arbovirus prevention and control. Extending this approach to other orthoflaviviruses could improve understanding of local viral co-circulation and promote the development of more precise and context-specific prevention strategies.
ER -