West Nile Virus Infection

摘要

West Nile virus (WNV) is the cause of West Nile disease (WND), a re-emerging disease of humans and animals transmitted by mosquitoes. Extensive epidemics of WND recently have occurred in Mediterranean and Eastern Europe, North Africa, and Asia. The first reported outbreak of WND in the Western Hemisphere began in New York City in 1999 and spread rapidly in subsequent years to affect humans, horses, birds and other species throughout North America. WNV currently is widely distributed throughout Africa, Asia, the Middle East, Europe and increasingly extensive portions of the Americas. WNV persists in an enzootic bird/mosquito cycle with wild birds as the primary reservoir hosts and Culex species as the major mosquito vectors. A remarkable variety of bird species (>140) have been infected during the North American epidemic of WNV infection, and mortality is very high in some of these (especially corvids [crows, raven, jays and magpies] and raptors [hawks, eagles and owls]). Humans, horses and some other animal species are incidental, dead-end hosts that are unimportant to the natural cycle of WNV transmission, although substantial numbers of both humans and horses have been affected during the transcontinental North American march of WNV (Table 1).