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  • West Nile Virus

    West Nile Virus - Fight the BiteWest Nile virus (WNV) has emerged in recent years in temperate regions of Europe and North America, presenting a threat to public and animal health. The most serious manifestation of WNV infection is fatal encephalitis (inflammation of the brain) in humans and horses, as well as mortality in certain domestic and wild birds. WNV has also been a significant cause of human illness in the United States. It first appeared in North America in 1999, and subsequently spread across the United States. WNV was first detected in Arizona in 2003.


    The best way to protect you and your family from WNV, or any other mosquito-borne illness, is to reduce the number of mosquitoes around your home and neighborhood and to take personal precautions to avoid mosquito bites.

    These are some of the preventative steps that you can easily take:

    • Eliminate standing water where mosquitoes can breed.
    • Check for items outside the home that collect rain or sprinkler water, such as cans, bottles, jars, buckets, old tires, drums, wheelbarrows, boats, kid pools, and other containers.
    • Change water in flower vases, birdbaths, planters and animal watering pans at least twice a week.
    • Repair leaky pipes and outside faucets, and move air conditioner drain hoses frequently.
    • Avoid being bitten by mosquitoes when going outside at night by using insect repellent.
    • Wear lightweight clothing that covers the arms and legs.
    • Report mosquito breeding problems (e.g. green pools) to your local environmental health office.
    • Limit time outdoors from dusk until dawn.
    • Use mosquito repellents that contain DEET, Picaridin, or Oil of Lemon Eucalyptus.
    • Check the screening on your windows and doors.
    West Nile Virus Hotline
    (520) 243-7999

    Information on Illness in Humans and Horses
    (520) 243-7797


    The chance of getting sick from West Nile Virus is low. Most people who are exposed to the West Nile virus do not have any symptoms, or have a mild illness that goes away on its own within a few days to a few weeks.

    Less than one out of 150 people who become ill with West Nile Virus will develop a more serious form of the infection such as meningitis or encephalitis, which will require hospitalization. Treatment is mostly supportive care. Currently, there is no vaccine for humans.

    Vaccines are available for horses. People are encouraged to vaccinate their horses. Pet birds should be kept indoors to limit mosquito exposure. Other livestock and pets are rarely affected by the West Nile virus. If you have questions or concerns about your livestock, please consult your veterinarian.

    West Nile Virus Transmission Cycle

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    Health Department

    3950 S. Country Club Road
    Ste. 100
    Tucson, AZ 85714

    (520) 243-7770

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