West Nile Virus (WNV) is an infection is transmitted by mosquitoes. West Nile Virus is a flavivirus commonly found in Africa, West Asia, and the Middle East. It is not known how long it has been in the United States, but CDC scientists believe the virus has probably been in the eastern US since the early summer of 1999, possibly longer. The virus can infect humans, birds, mosquitoes, horses, and some other mammals. West Nile fever is a case of mild disease in people, characterized by flu-like symptoms. West Nile fever typically lasts only a few days and does not appear to cause any long-term health effects.
Symptons of severe West Nile Virus illness can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological effects may be permanent. Up to 20 percent of the people who become infected have milder symptoms such as fever, headache, and body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Milder symptoms can last for as short as a few days, though even healthy people have become sick for several weeks. Approximately 80 percent of people (about 4 out of 5) who are infected with WNV will not show any symptoms at all. (more)
The best way to prevent West Nile Virus disease is to avoid mosquitoes and prevent mosquitoes from breeding. (more)
Mosquitoes become infected when they feed on infected birds, which may circulate the virus in their blood for a few days. Infected mosquitoes can then transmit West Nile virus to humans and animals when they bite.