West Nile Virus

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Need more information?
Call the Health Department's West Nile virus/EEE information line
1-800-913-1139 • Monday through Friday • 8:00 a.m.- 4:30 p.m.

What is West Nile virus?

West Nile virus is a disease caused by a mosquito-borne virus. West Nile virus first appeared in the United States in 1999, when at least 62 people in the New York City area got sick and seven people died. Since that time, the virus has spread throughout the United States, including Vermont. Horses are also commonly affected by this disease.

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How do people get West Nile virus?

The vast majority of infections come from the bite of an infected mosquito. Mosquitoes are infected when they feed on an infected bird. When an infected mosquito bites a person, the virus is injected into the person and may cause illness. West Nile virus can also be spread by organ transplantation, blood transfusion, from a mother to fetus, and possibly by breast milk.

Although birds and other animals may be infected with West Nile virus, there is no evidence that a person can get the virus from handling live or dead animals. However, wear gloves whenever handling a dead animal, including birds.

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If a mosquito bites me, will I get sick?

Most mosquitoes are NOT infected with West Nile virus. Even if an infected mosquito bites you, your chances of getting sick are low. Most people who are infected do not have any symptoms. Less than 1 percent of people who are infected develop severe illness, like encephalitis or meningitis. Another 20 percent of people who are infected have a milder illness.

People aged 50 and older have the highest risk of getting severely ill if bitten by a mosquito infected with West Nile virus.

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What are symptoms of West Nile virus infection?

In milder illness, symptoms may include fever, headache, body aches, skin rash and swollen lymph glands. Symptoms can last for as little as a few days but can last for several weeks. With more severe illness, people may have headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, paralysis and, rarely, death.

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How is West Nile virus infection treated?

There is no specific treatment for West Nile virus, but the symptoms can be treated. With severe illness, hospitalization and treatment in an intensive care unit may be required.

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How common is West Nile virus in Vermont ?

West Nile virus has been detected in dead birds, mosquitoes, and horses in Vermont. It is a relatively uncommon cause of illness in people. Since 2011, two or three infections in people have been reported each year. Prior to that, the most recent documented case of human illness was in 2003. The last reported case in a horse was in 2005. However, West Nile virus has been detected in mosquitoes and dead birds every year.

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Protect yourself from West Nile virus

The best way to protect yourself is to prevent mosquito bites.
You can take steps to reduce mosquito breeding areas near your home and prevent mosquito bites.

Keep mosquitoes from biting

Reduce the number of mosquitoes around your home

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More information

West Nile virus - Centers for Disease Control and Prevention

Arbovirus - Vermont Department of Health

Preventing Mosquito Bites:

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