Drivers of Rift Valley fever epidemics in Madagascar.

Renaud Lancelot (1) , Marina Béral (1, 2) , Vincent Michel Rakotoharinome (3) , Soa-Fy Andriamandimby (4) , Jean-Michel Heraud (4) , Caroline Coste (1) , Andrea Apolloni (1) , Cécile Squarzoni-Diaw (5) , Stéphane de La Rocque (1, 6, 7) , Pierre B H Formenty (8) , Jérémy Bouyer (1) , G R William Wint (9) , Eric Cardinale (10, 1)

1 UMR ASTRE - Animal, Santé, Territoires, Risques et Ecosystèmes
2 CRVOI - Centre de Recherche et de Veille sur les Maladies Émergentes dans l'Océan Indien
3 Centre National de la Recherche Appliquée au Développement Rural (FOFIFA), DSV [Antananarivo]
4 IPM - Unité d'Epidémiologie [Antananarivo, Madagascar]
5 Animal Production and Health Division [Rome]
6 World Organization for Animal Health
7 International Health Regulations Monitoring Procedure and Information Team
8 Emerging and Epidemic Zoonotic Diseases
9 Department of Zoology [Oxford]
10 CYROI - Cyclotron Réunion Océan Indien

Rift Valley fever (RVF) is a vector-borne viral disease widespread in Africa. The primary cycle involves mosquitoes and wild and domestic ruminant hosts. Humans are usually contaminated after contact with infected ruminants. As many environmental, agricultural, epidemiological, and anthropogenic factors are implicated in RVF spread, the multidisciplinary One Health approach was needed to identify the drivers of RVF epidemics in Madagascar. We examined the environmental patterns associated with these epidemics, comparing human and ruminant serological data with environmental and cattle-trade data. In contrast to East Africa, environmental drivers did not trigger the epidemics: They only modulated local Rift Valley fever virus (RVFV) transmission in ruminants. Instead, RVFV was introduced through ruminant trade and subsequent movement of cattle between trade hubs caused its long-distance spread within the country. Contact with cattle brought in from infected districts was associated with higher infection risk in slaughterhouse workers. The finding that anthropogenic rather than environmental factors are the main drivers of RVF infection in humans can be used to design better prevention and early detection in the case of RVF resurgence in the region.

Keywords: zoonosis; El Niño; One Health; cattle trade; vector-borne infection

Domains: Life Sciences [q-bio]; Microbiology and Parasitology; Virology

Renaud Lancelot, Marina Béral, Vincent Michel Rakotoharinome, Soa-Fy Andriamandimby, Jean-Michel Heraud, et al.. Drivers of Rift Valley fever epidemics in Madagascar.. Proceedings of the National Academy of Sciences of the United States of America, 2017, 114 (5), pp.938-943. ⟨10.1073/pnas.1607948114⟩. ⟨pasteur-01498224⟩