West Nile Virus is a virus that was first identified in Uganda in 1937. This virus was first identified in the United States in 1999 during an outbreak in New York. Since that time, the virus has been found in mosquitoes, birds, horses, and humans in various locations in the United States.

People may be exposed to WNV when an infected mosquito bites them. However, only a small percentage of mosquitoes are expected to carry the virus so the risk of being infected with WNV from any single mosquito bite is very small. For a mosquito to become infected with the virus, it must bite an infected bird.

No. Monitoring data in the United States have indicated that mosquitoes in the Culex group are most often infected with WNV. This is significant because most of the nuisance mosquitoes in Madison belong to the Aedes group, which are less likely to carry the West Nile Virus. Culex mosquitoes found in the Madison area (usually Culex pipens or Culex restuans) are considered to be evening and nighttime biters and commonly breed in stagnant or polluted water.

Most of the time, people infected with WNV will have no symptoms or will develop a mild illness that includes fever. In severe cases, encephalitis may develop. The Centers for Disease Control and Prevention (CDC) reports that less than 1% of persons that get infected will develop severe illness. Serious illness resulting from WNV can happen at any age; however, most cases of serious illness have occurred in persons greater than 50 years of age.

Reduce mosquito breeding sites. The Culex mosquitoes found in Madison prefer to breed in stagnant or polluted water. For this reason, eliminating standing water from your property may have a significant impact on reducing the number of Culex and other mosquitoes. Eliminate standing water around your home and neighborhood by: Keeping any containers from collecting rainwater (i.e. wheel barrows, flower pots, buckets, swimming pool covers, etc). Reduce the number of bites you receive.

When you are outdoors, use insect repellents containing DEET (N, N-diethyl-meta-toluamide). Follow the directions on the package. Many mosquitos are most active at dusk and dawn. Consider staying indoors during these times or use insect repellent and wear long sleeves and pants. Light colored clothing can help you see mosquitos that land on you. Get rid of mosquito breeding sites by emptying standing water from flower pots, buckets and barrels.

The virus was first detected in the West Nile region of Uganda in Africa in 1937. During the summer of 1999, the virus was detected in New York State. It is now found in most US states and across central and western Canada, but currently it is not in BC. While only a small number of mosquito species can carry and transmit the virus, some of these mosquitoes are present in BC.

WNV is spread only by adult mosquitoes that are infected with the virus. Humans and horses that have WNV infection cannot spread the disease directly to humans. The risk of getting WNV encephalitis is highest from late July through September. There is no evidence that a person can get WNV from handling live or dead infected birds. Still, you should avoid bare-handed contact when handling dead animals, including birds. If you must handle dead birds, use gloves or double plastic bags.

Besides birds, the virus has been identified in horses, cats, bats, chipmunks, skunks, squirrels, and domestic rabbits. Just recently it has been found in dogs. WNV is transmitted by infectious mosquitoes. There is no documented evidence that the virus is transmitted from animal to person.

There is currently no evidence that WNV can be spread directly from birds to people. However, dead birds carry a variety of diseases and therefore should never be handled with bare hands. Use gloves to carefully place dead birds in double-plastic bags and then place in the outdoor trash. Dead crows and blue jays that are found should be reported to the Macomb County Health Department for possible testing.

There is no specific treatment for WNV infection. In cases with mild symptoms, people experience symptoms such as fever and aches that pass on their own. In more severe cases, people usually need to go to the hospital where they can receive supportive treatment including intravenous fluids, help with breathing and nursing care.

For most, the risk is low. Less than 1 percent of people who are bitten by mosquitos develop any symptoms of the disease and relatively few mosquitos actually carry WNV. Greater risk for those outdoors a lot - People who spend a lot of time outdoors are more likely to be bitten by an infected mosquito. They should take special care to avoid mosquito bites.

Most mosquito bites cause itching and minor irritation. The symptoms of WNv range considerably and about 80 percent of people show no symptoms at all. Up to 20 percent have mild symptoms that may include fever, headache, vomiting and swollen lymph glands or a rash on the torso. These symptoms may last only a few days or persist for weeks. Less than 1 percent becomes seriously ill resulting in symptoms that can include meningitis, encephalitis, or polio-like paralysis.

Most WNV infections do not cause any symptoms. Mild WNV infections cause fever, headache and body aches, often with a skin rash and swollen lymph glands. In a small percentage of people infected by the virus, the disease can be serious, even fatal. More severe infections can cause headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, paralysis and, sometimes, death. Persons older that 50 years of age have a higher risk of developing severe illness.

There is no treatment for WNV infection. Doctors can treat the symptoms of WNV encephalitis. However, approximately 10% of people who become sick enough from the infection to be hospitalized die from it.

During 2001, three cases of WNV infection, including one death, were identified among residents of Massachusetts. Additionally, WNV has been found in horses, mosquitoes and many species of birds throughout the state. The mosquitoes that carry this virus are common throughout the state, and these mosquitoes are found in the city as well as in the woods and other less populated places.

Diagnosis of WNV infection is based on isolation of virus, demonstration of antibody to WNV, or demonstration of WN viral genomic sequences in tissue, blood, CSF or other body fluids. If you are a health care provider and suspect a case of WNV encephalitis, please call the MDPH's Division of Epidemiology and Immunization at (617) 983-6800.

WNV is NOT transmitted from person to person. For example, you cannot get infected by WNV from touching or kissing a person who has the disease, or from contact with a health care worker who has recently treated someone with the disease.

Since this virus was not detected in the Western Hemisphere until 1999, it is likely that native bird populations in the U.S. were not previously exposed to the virus. It is not unusual for a new disease to cause high rates of infection or death because they do not have natural immunity to the infection. It is not known if or how long it will take for populations to develop sufficient immunity.

No Symptoms In Most People:Approximately 80% of people who are infected with WNV will not show any symptoms at all. Mild Symptoms In Some People:Up to 20% of the people who become infected will display mild symptoms, including fever, headache, and body aches, nausea, vomiting and swollen lymph glands or a skin rash on the chest, stomach and back.Symptoms typically last a few days. Serious Symptoms In A Few People:About one in 150 people infected with WNV will develop severe illness.

WNV first appeared in California in 2002 with the identification of one human case. In 2003, three human cases occurred in California and WNV activity was detected in six southern California counties. By 2004, WNV activity was observed in all 58 counties in California and 830 human infections were identified. Click Here for a summary of West Nile Virus in California in 2004.

The continued expansion of WNV in the US indicates that it is permanently established in the Western Hemisphere. The virus is maintained within bird and mosquito populations.

This is a blood-borne disease transmitted by blood-sucking insects, primarily mosquitoes, most commonly the species Culex pipiens. Mosquitoes become infected after feeding on the blood of a bird that is carrying the virus. Infected mosquitoes may then transmit WNV to humans and other animals. Yes. By the end of 2001, there had been 149 human cases of WNV reported and confirmed in the US, including 18 fatalities.

Fatality rates of WNV range from 3 percent to 15 percent of those who become severely ill and are highest among the elderly and immuno-compromised individuals (such as cancer and AIDS patients).