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What is West Nile virus?

West Nile virus is a viral infection that is spread through the bite of mosquitoes that carry the virus. It can affect people and animals. In people, the symptoms are usually very mild. The CDC estimates that 8 out of 10 people have no symptoms at all. If symptoms do occur, they usually include fever, headache, general aching, a skin rash and swollen glands that get better without treatment. People with weak immune systems are at risk of more serious symptoms and complications from the virus. This includes encephalitis (life-threatening inflammation in the brain), which can occur if the virus travels to the brain. There is no vaccine for human use or specific cure for West Nile virus, so preventing mosquito bites is an important way to protect yourself, your family and your pets.
During the late 1990s and early 2000s, an outbreak of the West Nile virus had people reaching for the mosquito repellant in droves, as the brief epidemic resulted in 18 deaths, according to the U.S. Centers for Disease Control and Prevention. In 2002, a total of 284 fatalities were reported, spurring widespread public concern over the infection.

Vaccines, mosquito control and better treatment have vastly lowered the death rate of the West Nile virus. However, it remains a significant concern, especially for people whose immune systems are compromised or who are very young, very old or pregnant.

Symptoms of the virus include abdominal pain, diarrhea, fever, headache, loss of appetite, nausea, muscle pain, rash, sore throat and vomiting. In more severe cases, confusion, loss of consciousness, weakness, neck stiffness and loss of some sensation in one arm or leg may also occur.
Peter DeLucia
Health Education
West Nile virus is an arbovirus that is carried by mosquitos; it can be very serious, but generally its asymptomatic and those infected don't even realize they have it. Watch public health specialist Peter DeLucia, MPA, discuss West Nile virus.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.