Transmission dynamics and changing epidemiology of West Nile virus

Abstract

West Nile virus (WNV) is a flavivirus that is maintained in a bird-mosquito transmission cycle. Humans, horses and other non-avian vertebrates are usually incidental hosts, but evidence is accumulating that this might not always be the case. Historically, WNV has been associated with asymptomatic infections and sporadic disease outbreaks in humans and horses in Africa, Europe, Asia and Australia. However, since 1994, the virus has caused frequent outbreaks of severe neuroinvasive disease in humans and horses in Europe and the Mediterranean Basin. In 1999, WNV underwent a dramatic expansion of its geographic range, and was reported for the first time in the Western Hemisphere during an outbreak of human and equine encephalitis in New York City. The outbreak was accompanied by extensive and unprecedented avian mortality. Since then, WNV has dispersed across the Western Hemisphere and is now found throughout the USA, Canada, Mexico and the Caribbean, and parts of Central and South America. WNV has been responsible for >27,000 human cases, >25,000 equine cases and hundreds of thousands of avian deaths in the USA but, surprisingly, there have been only sparse reports of WNV disease in vertebrates in the Caribbean and Latin America. This review summarizes our current understanding of WNV with particular emphasis on its transmission dynamics and changing epidemiology.

Household survey of container–breeding mosquitoes and climatic factors influencing the prevalence of Aedes aegypti (Diptera: Culicidae) in Makkah City, Saudi Arabia

“…mosquitoes are known to be the most important vectors of West Nile virus (WNV) [53] of which infections are increasingly occurring in many parts of the world [54,55] including the Arabian Peninsula [56] . In nature, this flavivirus is maintained by a bird-mosquito transmission cycle [57,58] . Many people rear birds inside homes (Aziz, pers.…”

Le virus West Nile: diagnostic, surveillance et évolution épidémiologique en Europe

“…De plus, le VWN a été détecté pour la première fois en 1999 sur le continent américain, aux Etats-Unis et depuis, s'est répandu sur tout le continent nord américain ainsi qu'en Amérique centrale et latine (Blitvich 2008 (Kutasi et al 2011).…”

Characterization of West Nile Viruses Isolated from Captive American Flamingoes (Phoenicopterus ruber) in Medellin, Colombia

“…1,2 The virus can affect the nervous system of humans, horses, and birds, causing mild to severe illness and sometimes death. The WNV is a member of the Japanese encephalitis virus antigenic complex in the family Flaviviridae, genus Flavivirus.…”

“…In the following years, the virus spread through Canada, 10 Mexico, 11 Central America, the Caribbean, [12][13][14] and South America. 2,15 Despite causing disease in more than 12,000 humans, at least 25,000 equids, and hundreds of thousands of birds in the United States and Canada, there have been only a few reports of WNV disease in the Caribbean and Latin America. 2 The first report of the virus in Colombia appeared in 2005 following serological surveys of equids from the northern coastal area.…”

“…2,15 Despite causing disease in more than 12,000 humans, at least 25,000 equids, and hundreds of thousands of birds in the United States and Canada, there have been only a few reports of WNV disease in the Caribbean and Latin America. 2 The first report of the virus in Colombia appeared in 2005 following serological surveys of equids from the northern coastal area. 16,17 Recently, serologic evidence of WNV activity was found in horses from two Colombian provinces, Antioquia and El Meta, located in the northwestern and central-eastern regions of the country.…”