West Nile Virus
West Nile virus was recently introduced in wild birds and poses a potentially serious threat to people and horses. The virus spread quickly across the United States between 1999 and 2003.
Experts believe it is now established as a seasonal epidemic in North America, flaring up in the summer and continuing into the fall. The virus is most often spread when mosquitoes bite infected birds (such as house sparrows or robins), acquire the virus, and then pass it on to other animals or to humans. However, West Nile virus is fatal to many species of wild birds, such as crows, which are then only minimally involved in the spread of the infection. Many people infected with the virus do not become ill. Some experience mild symptoms, including fever, headache, body aches, nausea, vomiting, swollen lymph nodes, or a skin rash. About 1 in 150 develop severe illness and have symptoms that include high fever, headaches, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness, and paralysis.
Source: U.S. Fish and Wildlife Service.
Source: U.S. Fish and Wildlife Service.
End Notes
1 Insufficient laboratory resources also affected veterinarians’ and other responders’ abilities to
control outbreaks in a timely manner, according to numerous federal and state agency officials.
2 CDC officials told us that additional veterinarians may have been beneficial in getting more
horses vaccinated. In addition, they said difficulties implementing effective mosquito control programs and getting residents to adopt effective personal protection could also have contributed to a higher number of animal and human infections.
3 See GAO-06-467T.