West Nile Virus

What is West Nile encephalitis?
Viruses and bacteria can cause encephalitis (an inflammation of the brain) in humans and animals. West Nile encephalitis is a mosquito-borne infection of the brain caused by West Nile Virus(WNV).

How do people get West Nile encephalitis?
People get West Nile encephalitis from the bite of a mosquito that is infected-primarily the Culex group of species. The mosquito gets infected by biting a bird that carries the virus. WNV is not spread by person-to-person contact or directly from birds to people.

What is the transmission cycle of WNV in the environment?
Mosquitos become infected with WNV when they feed on infected birds. These infected mosquitos can then transmit WNV to humans and to other birds.

Is it only humans who become ill when infected with WNV?
No. Certain animals can also become ill. For example horses can develop encephalitis. Also certain birds, such as crows, blue jays, robins, and some hunting birds, like hawks and falcons.

What are the symptoms of West Nile encephalitis?
Most people who are infected with WNV have no symptoms or experience a mild illness, with fever and a headache. In some people, WNV can cause serious disease that affects the brain. It can cause serious neurological damage and be fatal. Symptoms generally occur 3 to 5 days following the bite of an infected mosquito and range from slight fever, headache, rash, swollen lymph nodes and conjunctivitis(irritation of the eye), to rapid onset of a severe headache, high fever, stiff neck, disorientation, muscle weakness, coma or death.

What percentage of WNV cases are fatal?
The fatality rate is 3% to 15% of people infected.

What is the risk of contracting West Nile encephalitis?
It is limited to persons in areas where there is virus activity, and is higher in persons 50 years of age or older. A 1999 survey of residents living in the most affected area of New York City showed that about 3% of the residents had been infected, and had either no illness or only mild illness.

Is there a treatment for West Nile encephalitis?
There is no specific therapy. In severe cases, supportive therapy-hospitalization, IV fluids, airway management, prevention of secondary infections (pneumonia) and nursing care-is needed.

Is there a vaccine for West Nile encephalitis?
There is no human vaccine at this time. There is a vaccine for horses, so consult with your veterinarian if you would like to vaccinate your horses.

If bitten by a mosquito should I be tested?
Illness related to mosquito bites are rare. However, see a doctor immediately if you develop symptoms such as, high fever, confusion, muscle weakness or severe headaches. People with mild symptoms are likely to recover completely and do not require any medication or lab testing.

Why is the state testing birds, and what should I do if I find a dead bird?
Crows, blue jays, and robins seem to be sensitive to WNV and provide an early warning system for detection of WNV activity. If a dead crow, blue jay, or robin is found between May 1 and October 15 and appears to have died of natural causes, please report to the Woodford County Health Department. We will be keeping a log of dead birds and locations. We will also be sending in up to ten birds (crows, blue jays, robins or other perching birds) for testing. Any birds submitted for testing must be dead less than 48 hours..

How can West Nile Virus infection be prevented?

  • Elimination of breeding sites:
    • get rid of old tires
    • store buckets, pet bowls, any containers, inside
    • change the water in bird baths and toddler pools weekly
    • put goldfish or bubblers in ornamental ponds
    • cover hot tubs, boats, canoes when not in use
    • maintain swimming pools
    • municipalities should consider applying larvicides in storm sewers in areas active with WNV
  • Protect self and others from bites:
    • apply insect repellents' containing Deet to clothing and skin, follow label directions
    • avoid activities in areas where mosquitos are present
    • wear long-sleeved shirt and pants when outdoors
    • alert health authorities to potential breeding sites in your area
    • report dead birds to OCHD
    • maintain window and door screens in your home

    Click Here for the IDPH West Nile Virus Web Page

    Click Here for the CDC West Nile Virus Web Page

    Click Here for the National Pesticide Information WNV Resource Web Page

    Illinois Bird Images:

  • http://www.illinoisraptorcenter.org/Field%20Guide/birdguide.htm
  • http://users.mrl.uiuc.edu/petrov/birds/

     

    Links

Pest Control Fact Sheets

CDC Lyme Disease

 

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