York Township, Michigan

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West Nile Virus

What is West Nile Virus?

West Nile Virus (WNV) is a mosquito-borne virus that can cause encephalitis or meningitis in humans and other animals. People get WNV from the bite of a mosquito that is infected with the virus.

How is WNV spread?

Mosquitoes become infected with WNV when they feed on infected birds that carry the virus in their blood. After 10-14 days the mosquitoes can transmit the virus to humans and animals while biting to take blood. Once the virus is in someone's bloodstream, it multiplies and may cause illness. You cannot "catch" the virus from touching someone with the disease.

What is the risk of illness in humans?

The risk of getting West Nile encephalitis/meningitis is limited to people who are in areas where WNV is present. The chances you will become seriously ill from any one mosquito bite are extremely small. The risk of getting sick is higher for people who are over 50 years of age, or persons with a weakened immune system.

What are the symptoms?

Most people infected with WNV do not have any symptoms of illness, but some (1 in 4) may become ill 3-15 days after the bite of an infected mosquito. In a few cases, mostly among the elderly, death may occur. Mild illness: Slight fever, headache, body aches, and sometimes a skin rash and swollen glands. Serious illness: High fever, severe headache, stiff neck, mental confusion, convulsions, muscle weakness and paralysis.

How is WNV treated?

There is no specific treatment for West Nile encephalitis/meningitis since antibiotics are not effective against this virus. Hospitalization is usually necessary for supportive care, which may include intravenous fluids (IV), prevention of pneumonia, and breathing assistance, if necessary.

How is West Nile encephalitis prevented?

There is no vaccine for humans available, but there are many steps that you can take to reduce your risk of becoming infected...they include:

1. Avoid activities in areas where there are large numbers of mosquitoes and at the times when they are most active, which is as the sun rises and sets.

2. Wear long-sleeved shirts and long pants whenever your are in mosquito-filled areas.

3. Apply insect repellent that contains DEET to exposed skin; spray clothing with repellent because mosquitoes may bite through thin clothing. Wash repellent off after coming back indoors. NOTE: whenever you use an insect repellent, be sure to read and follow the label directions for safe use. CAUTION: do not use DEET repellent on children under 2 yrs. of age or during pregnancy.

4. Avoid applying repellent to the hands of children because repellents may irritate the eyes and mouth.

5. Repair and maintain window and door screens to keep mosquitoes out of buildings.

6. Limit mosquito breeding sites by draining standing water in your yard. Empty water from flower pots/saucers, clogged drain gutters, wading pools, swimming pool and patio furnature covers, discarded tires, pails and buckets and other similar items that can collect water. Change the water in birdbaths and horse troughs at least 2 times per week.

7. Cut tall weeds and grass to remove mosquito hiding and resting areas.

How do we monitor for the disease?

We collect and test mosquitoes and dead crows for WNV. We also monitor and test ill humans and horses for WNV, St. Louis Encephalitis (SLE) and Eastern Equine Encephalitis (EEE).

Can West Nile Virus infect other animals?

Although the vast majority of infections have been identified in birds, the Centers for Disease Control have received reports of WNV in horses, dogs, cats, bats, chipmunks, skunks, squirrels, domestic rabbits and raccoons. There is NO evidence that WNV can be transmitted from animals to humans.

How to report a dead crow?

Please call the Washtenaw County West Nile Virus Hotline at: 734-484-7200, or call the State of Michigan West Nile Virus Hotline at: 1-888-668-0869


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