title: Identifying Areas Suitable for the Occurrence of Rift Valley Fever in North Africa: Implications for Surveillance.
abstract: Rift Valley fever (RVF) is a vector-borne zoonotic disease that has caused widespread outbreaks throughout Africa and the Arabian Peninsula, with serious consequences for livestock-based economies and public health. Although there have never been any reports of RVF in Morocco, Algeria, Tunisia and Libya, it is a priority disease in the Maghreb, due to the threat of introduction of the virus through transboundary livestock movements or infected mosquito vectors. However, the implementation of surveillance activities and early warning contingency plans requires better knowledge of the epidemiological situation. We conducted a multicriteria decision analysis, integrating host distribution with a combination of important ecological factors that drive mosquito abundance, to identify hotspots and suitable time periods for RVF enzootic circulation (i.e. stable transmission at a low to moderate level for an extended period of time) and an RVF epizootic event (i.e. a sudden occurrence of a large number of infected animals over a large geographic area) in the Maghreb. We also modelled vector species distribution using available information on vector presence and habitat preference. We found that the northern regions of the Maghreb were moderately suitable for RVF enzootics, but highly suitable for RVF epizootics. The vector species distribution model identified these regions as the most favourable mosquito habitats. Due to the low density of animal hosts and arid conditions, the desert region showed low RVF suitability, except in oases. However, the presence of competent vectors in putative unsuitable areas underlines the need for further assessments of mosquito habitat preference. This study produced monthly RVF suitability maps useful for animal health managers and veterinary services involved in designing risk-based surveillance programmes. The suitability maps can be further enhanced using existing country-specific sources of information and by incorporating knowledge - as it becomes available - on the epidemiology of the disease and distribution of vectors in the Maghreb.
authors: Unité Epidémiologie, Laboratoire de Lyon, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES), Lyon, France.
authors: E
authors: E
authors: Arsevska
authors: Institut de Recherche Vétérinaire de Tunisie (IRVT), Tunis, Tunisie.
authors: J
authors: J
authors: Hellal
authors: Institut de Recherche Vétérinaire de Tunisie (IRVT), Tunis, Tunisie.
authors: S
authors: S
authors: Mejri
authors: Centre Nationale de Veille Zoosanitaire (CNVZ), Tunis, Tunisie.
authors: S
authors: S
authors: Hammami
authors: Unité Virologie, Laboratoire de Lyon, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES), Lyon, France.
authors: P
authors: P
authors: Marianneau
authors: Unité Epidémiologie, Laboratoire de Lyon, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES), Lyon, France.
authors: D
authors: D
authors: Calavas
authors: Unité Epidémiologie, Laboratoire de Lyon, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES), Lyon, France. viviane.henaux@anses.fr.
authors: V
authors: V
authors: Hénaux
mesh_terms: D000352:Africa, Northern; D000818:Animals; D009033:Culicidae / Q000821:virology*; D004196:Disease Outbreaks / Q000517:prevention & control*; D006801:Humans; D058751:Livestock / Q000821:virology; D011159:Population Surveillance; D012295:Rift Valley Fever / Q000453:epidemiology*; D015047:Zoonoses
keywords: Rift Valley fever; mosquito habitat distribution; multicriteria decision analysis; spatial risk; vector-borne disease; zoonotic disease