West Nile Disease Epidemiology in North-West Africa: Bibliographical Review

Abstract

West Nile fever (WNF) or West Nile disease (WND) is a mosquito-borne viral disease that can affect birds, humans and horses. West Nile virus (WNV) is a member of the genus Flavivirus in the family Flaviviridae. WNV is maintained in a mosquito-bird-mosquito transmission cycle, whereas humans and horses are considered dead-end hosts. In human and horses, symptoms range from unapparent infection to mild febrile illness, meningitis, encephalitis or death. WNV has a wide geographical range that includes portions of Europe, Asia, Africa, Australia (Kunjin virus), and in North, Central and South America. Migratory birds are thought to be primarily responsible for virus dispersal, including reintroduction of WNV from endemic areas into regions that experience sporadic outbreaks (Fields Virology, 2001, Lippincott Williams and Wilkins, Philadelphia, Pennsylvania, USA, 1043-1125). The occurrence of disease in humans and animals along with birds and mosquitoes surveillance for WNV activity demonstrates that the virus range has dramatically expanded including North, Central and South America as well as Europe and countries facing the Mediterranean Basin. WND infection in humans has been reported in Morocco in 1996 (Virologie, 1, 1997, 248), in Tunisia in 2007 (Ann. N. Y. Acad., 951, 2001, 117) (Med. Trop., 61, 2001, 487) and 2003 (Epidémiologie de la fièvre West Nile, 2012, Thèse de doctorat, Université Montpellier II, Sciences et techniques du Langueduc, Montpellier, France), and in Algeria in 1994 (Rev. Sci. Tech., 31, 2012, 829). Outbreaks of equine encephalitis have been also reported in Morocco in 1996 (Bull. OIE, 11, 1996, 867), in 2003 (Emerg. Infect. Dis., 11, 2005, 306) and in 2010 (World Animal Health Information Database. WAHID, 2010). Serological evidence of WNV has been demonstrated in the three countries in many species. The aim of this review was to assess the epidemiological situation of WND in north-west Africa comprising Morocco, Algeria and Tunisia, with an updated literature review based on of human cases and equine outbreaks reports as well as serological studies in these countries.

Keywords: Algeria; Morocco; North Africa; Tunisia; West Nile Virus; horse; human.