What is West Nile virus?

West Nile virus is transmitted to humans by the bite of an infected mosquito. It doesn't spread from person to person.

Most people with West Nile virus recover fully and may not even have symptoms. But some people have mild signs and symptoms such as fever, headache, muscle aches, nausea, vomiting, and sometimes swollen glands or a rash on the chest, stomach, and back. These can last 3 to 6 days.

A few people have more serious problems, such as high fever, a stiff neck, confusion, tremors, seizures, muscle weakness, loss of vision, and numbness. These can last several weeks and may lead to permanent muscle weakness or brain damage, which can be fatal. Of nearly 981 Americans infected with West Nile virus in 2010, 45 died.

If you have any serious signs and symptoms, see a healthcare provider at once or call 911. People over age 50 and those with weakened immune systems are at most risk for serious problems and death.

How will my healthcare provider know I have West Nile virus?

Signs and symptoms of West Nile virus can mimic other illnesses, so your healthcare provider will want to find out if you could have been exposed to the virus. Tell your healthcare provider if you've been bitten by mosquitoes recently or if you've been in an area where people or animals have been sick with West Nile virus. Your healthcare provider will take a blood sample to test for the virus.

If you're sick enough to be admitted to the hospital, your healthcare provider may also need to test a sample of your spinal fluid.

How is West Nile virus treated?

No specific medicine or treatment is available for West Nile virus. Most people recover fully with rest and -routine care. Your healthcare provider will tell you how to manage a headache, fever, and nausea. But if you have a severe illness, you may need to be hospitalized for I.V. medicine and breathing support while you recover.

What can I do to protect myself and my family?

Make yourself less attractive to mosquitoes by following these tips:

* Limit your time outside between dusk and dawn.

* Wear protective clothing (long sleeves, long pants, and socks).

* Place mosquito netting over infant carriers or strollers when outdoors.

* Use an insect repellent containing DEET. Follow the directions on the label when applying the repellent. Don't use repellents containing DEET on infants under 2 months old.

* Keep swimming pools, outdoor saunas, and hot tubs clean and properly chlorinated.

* Remove standing water from pool covers and other places where mosquitoes can breed. Drain plastic wading pools and set them on their sides when you're not using them. Don't let containers become filled with standing water. Store empty flowerpots or trash cans indoors or drill holes in the bottom.

* Make sure rain gutters drain properly so water doesn't collect.

* Install or repair window and door screens on your house so mosquitoes can't get indoors.