West Nile Virus (WNV) Frequently Asked Questions

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  • How do people get West Nile Virus?

    Mosquitoes become infected with West Nile virus by biting an infected bird. When these mosquitoes then bite a human, the human contracts the virus. West Nile virus is not spread by person-to-person contact and there is no evidence of the virus spreading to people by handling infected live or dead birds.

  • Who is at the highest risk for the West Nile virus?

    All residents of areas where the virus has been identified are at risk of getting the West Nile virus. Individuals over the age of 50, those with diabetes, those with high blood pressure, and those with compromised immune systems are at the highest risk of developing serious complications.

  • What are the symptoms of West Nile virus? How many people experience these symptoms?

    About 80% of people infected with the West Nile virus experience no symptoms. The remaining 20% who become infected may have fevers, headaches, body aches, nausea, vomiting, swollen lymph glands or a skin rash on the chest, stomach and back. Symptoms can last for a few days to several weeks. About one in 150 people infected with WNV develop serious illness. The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks and neurological effects may be permanent. Serious symptoms may lead to long-term illness or death.

  • What is the death rate for West Nile Virus?

    The percentage of fatal cases of West Nile virus is less than 1%.

  • How long does it take to get sick if bitten by an infected mosquito?

    Since most infected people experience no symptoms, being bitten by an infected mosquito does not necessarily mean you will get sick. When illness does occur, it usually develops between 3 and 15 days after being bitten by an infected mosquito.

  • How long has West Nile Virus been in the United States?

    United States health officials first detected the virus in 1999. Since then, 48 states have reported confirmed cases of West Nile virus.

  • Is West Nile virus contagious? Can it be passed between humans or from animal to human?

    West Nile virus can not be transmitted from person-to-person. You can not get West Nile virus from touching or kissing a person who has the disease or from a health care worker who has treated someone with the disease. Scientists also believe that a human cannot be infected with the virus by handling a live or dead animal infected with the West Nile virus.

  • What is the peak season for West Nile Virus?

    In most areas of the country, the time when the West Nile virus is most prevalent is from August to October.

  • What should I do if I find a dead bird? How do I report it, and which kinds of birds should I report?

    If you find a dead bird, please report it to the County of San Diego Vector Control Program by calling (858) 694-2888 or fill out an online reporting form. Dead birds will be collected and tested for the West Nile virus. Please report the bird only if it has been dead for less than 24 hours, is not covered by ants and is intact.

    Types of dead birds to report: Crow family (crows, ravens, and jays) and birds of prey (hawks, owls, falcons)

  • What precautions can I take to prevent mosquito bites?

    When outdoors, especially at dawn and dusk, wear long-sleeved, light colored shirts and long pants. Insect repellent containing DEET, picaridin, and lemon of eucalyptus oil work best. You can also prevent mosquito bites by preventing mosquito breeding. Mosquitoes breed in standing water sources, such as neglected pools, plant saucers, spare tires, birdbaths and decorative ponds. Removing these types of standing water sources from your property will stop mosquitoes from breeding, and in turn, stop them from biting you. If you do have standing water sources on your property, drain them or stock them with mosquito eating fish or mosquito donuts. Mosquito fish are small, guppy-like fish that eat mosquito larvae before they turn into biting adults. You can get them for free throughout the county at 13 different locations. Mosquito donuts are small, donut-shaped tablets that contain Bti, a naturally occurring bacteria that kills mosquito larvae in water.