General information

Questions about West Nile Virus

How can I protect myself from West Nile Virus?

The best way to protect yourself from West Nile virus is to avoid exposure to mosquito bites:

  • Keep mosquitoes out of your home by keeping doors and windows closed or tightly screened.
  • Wear insect repellent when outdoors, especially at dusk and dawn when the mosquitoes that transmit West Nile virus are active. Wear long sleeves and pants to protect yourself from bites.
  • Eliminate standing water around your home where mosquitoes can reproduce.

Can I use natural repellents?

Products containing DEET, Picaridin, oil of lemon eucalyptus, or IR3535 are recommended for prevention of mosquito bites. Both oil of lemon eucalyptus and IR3535 are considered biopesticide repellents by the US EPA.

Some ‘home remedies’ or products marketed as insect repellents may not contain active ingredients that have been tested for safety and effectiveness. If you choose to use a product containing another active ingredient, be aware that it may need to be applied more often or may not be effective at preventing mosquito bites.

What is West Nile Virus?

West Nile Virus is a mosquito-borne disease that originated in Africa. It first appeared in the United States in 1999 and it moved West until it reached California in 2003. It is present throughout the year, although illness is often associated with peaks during hot summer months. You can learn more here.

How dangerous is West Nile Virus?

Illness associated with West Nile virus varies by the severity of symptoms: 1) Severe illness associated with nervous system malfunctions 2) An extended flu-like illness with high fever and excessive sleep 3) No illness at all.

  • Serious Symptoms: Less than 1% (1/150) of those infected with West Nile virus will have more severe symptoms that may include: high fever, headache, neck stiffness, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness, and paralysis.
  • Milder Symptoms: About 20% (1/5) of those infected display milder symptoms which can include: fever, headache, body aches, nausea, vomiting, and a skin rash. Symptoms generally last for a few days, although some people have been sick for several weeks.
  • No Symptoms: About 80% (4/5) of those infected with West Nile virus have no symptoms and feel nothing at all. In this group, the body produces an antibody that attacks the virus and the individual never gets sick.

Adults over age 50 are at increased risk for serious illness associated with West Nile virus infection.

Is there a vaccine for West Nile Virus?

There is not a human West Nile virus vaccine, but there is a vaccine available for horses.

What do dead birds have to do with West Nile Virus?

Dead birds, especially corvids (crows, ravens, and jays) are often a sign that West Nile virus is present in an area. Testing dead birds for West Nile virus is one of the most important disease surveillance tools we have.

What should I do if I find a dead bird?

If the bird appears to have been dead less than 24 hours, shows no signs of decomposition, and does not have any obvious trauma or injury, call 877-WNV-BIRD or report it online at

Do all mosquitoes have West Nile Virus?

Not all mosquito species carry West Nile virus, and even among mosquitoes capable of carrying the virus, most are NOT infected. Being bitten by a mosquito does not automatically mean you will be infected with West Nile virus.

What should I do if I think I have West Nile Virus?

If you believe you have West Nile virus, or any other medical problem, consult a medical professional.

Can I get West Nile virus from birds or animals?

There has never been any documented case of West Nile virus transmission to humans from an animal other than a mosquito.

What are sentinel chickens?

You can learn about our sentinel chicken program here.

How do you monitor West Nile virus?

You can learn about our West Nile virus and other mosquito-borne disease surveillance programs here.