West Nile Virus Information

Commonly Asked Questions about West Nile Virus

West Nile Virus (WNV) is transmitted by the bite of an infected mosquito. It first appeared in the United States in 1999 in the greater New York City area. In 2000, it spread to all of the New England states and south to North Carolina. It has caused illness in humans, wildlife, and domestic animals, especially birds and horses.

For most individuals with a healthy immune system, WNV infection may cause no symptoms or mild flue-like symptoms with no long-term complications. For those with a weakened immune system or over 50 years of age, WNV may result in illness. Approximately 20% of those infected develop mild illness with symptoms generally lasting 3 to 6 days.

Surveillance of the West Nile Virus is important because it affects not only people, but also wildlife (including many game animals) and some domestic animals.

What is West Nile?
How is the disease spread?
History of West Nile in Ohio
What are the risks?
What are the Symptoms?
What to do if you think you may have it?
Why do local health departments want to know about dead birds?
What should I do if I find a dead crow or blue jay?
Are animals at risk?
What can I do to protect myself?
What can I do to reduce the number of mosquitoes on my property?

For more information, please see the links below:

Center for Disease Control
Ohio Department of Health
Ohio State University
National Pesticide Communications Network
ODH Vector Borne Disease Program: (614) 752-1029 Email

What is West Nile?
Primarily a wild-bird disease, West Nile Virus, or WNV, is a mosquito-borne virus which generally causes mild symptoms that mimic the flu in humans. In rare instances, however, WNV can cause encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord). The very old, the very young, and those with compromised immune systems are most susceptible to the serious complication related to the virus.

For a description of the virology of the disease CLICK HERE

How is the disease spread?
West Nile virus is spread to humans by the bite of an infected mosquito. When a mosquito bites a bird that carries the virus, the mosquito becomes infected. Once a mosquito is infected, it may transmit the virus to people or animals when it bites them. About 1 in 150 people bitten by an infected mosquito develop symptoms.

WNV is not transmitted person-to-person or animal-to-person

For a detailed history of the disease’s spread in the United States CLICK HERE

For a map of states affected by the disease, please CLICK HERE to be sent to the National Wildlife Health Center

History of West Nile in Ohio
WNV was first detected in Ohio in August 2001 in a Lake County blue jay. By the end of summer, the virus had been detected in 54 blue jays and 226 crows around the state. To date in 2002, the Ohio Department of Health in cooperation with local health officials has found WNV in 456 birds in 79 counties.

What are the risks?
Fewer than 1 percent of mosquitoes are infected, even in areas where the virus has been detected. Only 1 in 150 people bitten by an infected mosquito will develop symptoms. Most people will have a mild illness, but 10 to 15 percent of them will develop a more serious illness.

Among those with severe illness due to West Nile virus, case-fatality rates range from 3% to 15% and are highest among the elderly. Less than 1% of persons infected with West Nile virus will develop severe illness.

What are the Symptoms?
Most people who are bitten by an infected mosquito will have no symptoms or only mild symptoms that will last a couple of days. These symptoms may include:

Fever
Headache
Body aches
Persons infected often develop a skin rash and swollen lymph glands.

A more serious infection may cause headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, occasional convulsions, and paralysis. At its most serious, it can cause permanent brain damage and can be fatal.

What to do if you think you may have it?
If you feel you may have symptoms of West Nile, see your doctor.

Why do local health departments want to know about dead birds?
West Nile is a bird-borne disease. As carriers, birds can carry the virus to new locales before dying. A dead bird that shows no other sign of injury or reason for death may have died from a West Nile virus infection.

Blue jays and crows are being tested because they are the birds most susceptible to West Nile and are predictors of the disease’s presence.

To see more information on Ohio’s surveillance plan, please CLICK HERE

What should I do if I find a dead crow or blue jay?
If you find a dead crow or blue jay with no visible sign of injury or cause of death, contact your local health department.

Note the location(address, county, zip), how many, and when it was found.
Always avoid bare handed contact with a dead bird. Use gloves and double bag the bird before disposing of the bird.

There is no evidence that a person can get the virus from handling live or dead infected birds. There is no evidence that a person can get the virus from handling live or dead infected birds. However, persons should avoid bare-handed contact when handling any dead animals.

To see pictures of crows and blue jays please CLICK HERE

Are animals at risk?
WNV is not considered a major risk to dogs and cats. Only a few have been reported with WNV infection.

Horses can become infected. Clinical signs of West Nile virus infection in horses include: listlessness, stumbling, lack of coordination, partial paralysis, and death. Horses with West Nile virus often do not have a fever. Horses can be protected by vaccination.

For more information CLICK HERE

What can I do to protect myself?
You can take the following steps to protect yourself from being bitten by an infected mosquito:
Personal Prevention Measures

Avoid being outdoors during peak mosquito biting periods, which are dawn and dusk.
Wear light-colored, long-sleeved shirts and long pants.
Use mosquito repellent containing DEET according to label directions. Adults should use repellent with no more than 30 percent DEET; for children, 10 percent or less(for more information on the use of repellents please CLICK HERE)
Make sure that doors and windows have and keep them in good repair

Remember that using Vitamin B, ultrasonic devices, incense and bug zappers has not been shown to be effective in preventing mosquito bites.

What can I do to reduce the number of mosquitoes on my property?
The most effective way to reduce the presence of mosquitoes is to eliminate potential breeding grounds. Standing water of any nature can become a haven for mosquito larva.

Remove old, used tires from your property or put them under cover so the don’t collect water
Dispose of tin cans, plastic containers, ceramic pots, or similar water-holding containers.
Make sure roof gutters drain properly. Clean clogged gutters in spring and fall.
Clean and chlorinate swimming pools, outdoor saunas and hot tubs. If not in use, keep empty and covered.
Drain water from pool covers.
Change the water in birdbaths at least once a week.
Turn over plastic wading pools, wheelbarrows, etc. when not in use.
Eliminate any standing water that collects on your property.
Remind or help neighbors to eliminate breeding sites on their properties.

Repellents
If you will be outside during evening, nighttime and dawn hours, consider the use of an over the counter insect repellant. Before use, it is important that you review the safety precautions listed on the repellent and know the emergency response if misused. Some specific suggestions are listed below but are not inclusive and may not apply to all brands.

Some common brands include Off, Rutgers 6-12, Cutter’s, Repel, Deep Woods Off!, Muscol, and Ben’s. Common ingredients include ethyl haxanediol, dimethl phthalate, dimethyl carbate and DEET.

When using DEET, use 10% or less DEET (N, N-diethyl-methyl-meta-toluamide) for children and no more than 30% DEET for adults. DEET is effective for approximately four hours. Avoid prolonged or excessive use of DEET and use it sparingly to cover exposed skin and clothing.
Do not use DEET on infants or pregnant women and do not apply DEET directly to children. Apply it to your own hands and then put it on the child. Always use repellants according to the manufacturer’s instructions.
Community-wide mosquito spraying, which kills adult mosquitoes, called adulticiding, is also not recommended. It is considered by the Ohio Department of Health to be the least desirable method of control due to its temporary effect, lasting only 3-4 hours maximum.

For more specific information on the use of repellents and pesticides, please click the link below to be transferred to the National Pesticide Information Center