| West Nile emerged in 1937 in
Africa
and first appeared in
North America
in 1999 in New York. Similar to the other encephalitis, it is cycled between birds and
mosquitoes and transmitted to mammals including horses and man by infected
mosquitoes.
Over 36 species of mosquitoes have tested positive for WN virus, the Culex
pipiens pipiens complex seems to be the most common species associated with
human and horse cases. In 2006, there were 4,256 human cases in the United
States. Three human cases were reported in Florida. |
