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West Nile virus human cases in Wyoming occur primarily in the late summer or early Fall, although the mosquito season is April through October. The majority of people who get infected with the virus have no illness, or at most, have an infection similar to a mild flu with fever, headache and fatigue. Rarely will the virus multiply in the central nervous system and cause the brain disease called encephalitis.

It can occur however. In fact, two-thirds of people who develop encephalitis or meningitis have serious long-term health problems and some people never fully recover.

Wyoming has three kinds of arboviral encephalitis: West Nile encephalitis, Saint Louis encephalitis, and Western Equine encephalitis.

An arboviral Encephalitis is an infectious disease that affects the brain. The disease is caused by a virus which attacks and destroys some nerve cells and causes brain inflammation and swelling. Encephalitis arboviruses belong to several families of viruses that usually infect birds and are transmitted from bird to bird by mosquitoes.

What is West Nile Encephalitis?

West Nile Encephalitis is caused by West Nile virus, a flavivirus previously only found in Africa, Eastern Europe, and West Asia. West Nile virus is closely related to St. Louis Encephalitis Virus (SLEV) which is found in the United States and to the Japanese Encephalitis virus from South East Asia and to Murray Valley fever virus from Australia and New Guinea.

How can I get it?

The principle route of human infection is through the bite of an infected mosquito.   

In 2002, additional routes became apparent; however, this represented a very small proportion of cases. These routes include receiving transplanted organs and blood transfusions, transplacental and possibly breast-feeding transmission, and laboratory workers working with West Nile infected products.

Who is most at risk?

Anyone can get the virus; however, people over 50 years of age have the highest risk of developing a severe illness because as we age, our bodies have a harder time fighting off disease. People with compromised immune systems are also at increased risk.

What are the symptoms?

People with mild infections may experience fever, headache, body aches, skin rash and swollen lymph glands. This is called West Nile fever.

People with more severe infections may experience high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, and paralysis. This is called West Nile encephalitis. If you have any of these symptoms, contact your health care provider.

Are there long-term consequences?

While most infections are usually mild, West Nile Encephalitis can result in death or serious brain damage. The CDC notes that neurological effects may be permanent. Some improvements may be seen over time.

Is there treatment or a vaccine?

There is no specific treatment for West Nile virus infection, nor a vaccine. While most people fully recover from the viral infection, in some severe cases hospitalization may be needed.

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