What is West Nile Virus?

West Nile is a mosquito-borne virus that can cause encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord). It first appeared in the U.S. in 1999 in New York City.

West Nile virus is spread to humans by the bite of an infected mosquito. A mosquito becomes infected by biting a bird that carries the virus. You or your child cannot get West Nile virus from a person who has the disease. West Nile virus is not spread by person-to-person contact such as touching, kissing or caring for someone who is infected.

Yes. While the chance of anyone becoming infected with West Nile virus is very low, most cases have occurred in people older than 50. People in this age group, especially the elderly, are also more likely to develop severe diseases, such as encephalitis or meningitis, if they become infected.

Outbreaks of West Nile viral disease have occurred in Africa, Egypt, Israel, Asia, Romania, Russia and France. Before 1999, however, West Nile virus had never before been found in the Americas. The most likely explanation for its appearance here is that the virus was introduced by an infected bird that was imported or an infected person returning from a country where the virus is common.

Can you get West Nile virus directly from birds?

There is currently no evidence that West Nile virus can be spread directly from birds to people. However, dead birds can carry a variety of diseases and, therefore, should never be handled with bare hands. Use gloves to carefully place dead birds in double-plastic bags and then place in the outdoor trash. Please visit How to Report a Dead or Sick Bird or Mammal to submit a report, or contact your local health department.

No. There is no evidence to suggest that ticks or other insects transmit West Nile virus.

Most people who are infected with West Nile virus either have no symptoms or experience mild illness such as a fever, headache and body aches. Some persons may develop a mild rash or swollen lymph glands. In some individuals, particularly the elderly, West Nile virus can cause serious disease that affects brain tissue. At its most serious, it can cause permanent neurological damage and can be fatal. Symptoms of encephalitis (inflammation of the brain) include the rapid onset of severe headache, high fever, stiff neck, confusion, loss of consciousness (coma) or muscle weakness, and may be fatal.

There is no specific therapy. In more severe cases, intensive supportive therapy is indicated, such as hospitalization, intravenous (IV) fluids and nutrition, airway management, ventilatory support (ventilator) if needed and prevention of secondary infections (pneumonia, urinary tract, etc.).

No. Human vaccines are still being developed and may be available in the future. There is currently a vaccine available for horses.

Being bitten by an infected mosquito will not necessarily make you sick. Most people who are infected with West Nile virus have no symptoms or experience only mild illness. If illness were to occur, it would occur within 3 to 15 days of being bitten by an infected mosquito.

From April to October, take the following precautions: If outside from dusk to dawn when mosquitoes are most active, or during the day in an area where there are weeds, tall grass or bushes, people should wear protective clothing, such as long pants, loose-fitting, long-sleeved shirts and socks. Consider the use of an insect repellent containing DEET, according to the manufacturer's directions on the label.

Mosquitoes lay their eggs in standing or slow-moving water such as streams or creeks. Weeds, tall grass and bushes provide an outdoor home for mosquitoes. They can enter homes through unscreened windows or doors, or broken screens.

• Make sure that doors and windows have tight-fitting screens. Repair or replace all screens that have tears or holes.

• Drain all standing water in the yard weekly. Empty water from mosquito breeding sites, such as flower pots, pet bowls, clogged rain gutters, swimming pool covers, discarded tires and similar sites in which mosquitoes can lay eggs.

• Remind or help neighbors to eliminate breeding sites on their properties.

If you develop signs of encephalitis with fever, muscle weakness, and confusion, you should seek medical care immediately.

Rare cases have been reported in dogs and cats. They are not a source of infection for people and other animals. There is no specific therapy beyond supportive care.