West Nile Virus (WNV) infection is an illness transmitted to humans primarily by mosquitoes. The pathogen that causes WNV infection is a virus that is known to infect birds and other animals as well as humans. People working outside are at risk, particularly in warmer weather (when mosquitoes are more likely to be present). The following information is designed to educate and offer ways to reduce the risks of infection.
In most cases, persons infected with WNV either show no symptoms or have very mild flu-like symptoms, called West Nile fever. These mild cases of West Nile fever normally last only a few days and are not believed to cause any long-term effects. The typical time from infection to the onset of signs and symptoms is 3 to 14 days. Signs and symptoms of the milder illness, West Nile fever, include headache, fever, body aches, swollen lymph nodes, and/or a skin rash on the body.
According to the Centers for Disease Control and Prevention (CDC), severe illness is reported to occur in about 1 in every 150 persons infected with WNV. Symptoms of severe disease may last several weeks and may have permanent neurological effects. The signs and symptoms of more severe infection (West Nile encephalitis or meningitis) include headache, high fever, stiffness in the neck, disorientation (in very severe cases, coma), tremors and convulsions and muscle weakness (in very severe cases, paralysis).
Persons who develop symptoms of severe WNV illness should seek medical attention immediately, as this disease can be fatal.
How can people become exposed? Flooded areas, particularly in warm climates, provide the opportunity for mosquitoes to breed in stagnant water. Bites from infected mosquitoes may result in WNV.
Keep in mind that elimination of mosquito breeding grounds is a highly effective way of reducing mosquito populations and reducing the number of mosquito bites. Mosquitoes lay eggs in standing water. People working in and around areas of stagnant water should:
It may not always be possible to eliminate all potential mosquito breeding grounds. Minimizing the risk of mosquito bites is important in reducing the risk of WNV infection. People who work outdoors should be aware that the use of personal protective equipment and techniques is essential to preventing mosquito bites. Everyone should: