West Nile Virus - Frequently Asked Questions

Has West Nile virus been found in Connecticut?
Yes, WNV has been found each year since 1999 in mosquitoes, horses, wild birds, or people. Some years the virus has been found in most areas of the state.

Where did West Nile virus come from?

West Nile virus is named after the West Nile district of Uganda where the virus was first isolated in 1937. Outbreaks of the West Nile illness have occurred in Egypt, Asia, Israel, South Africa, and parts of Europe and Australia. Before 1999, WNV had not been found in the United States. The virus may have been brought to the United States by an infected bird that was either imported or migrated from a country where the virus is common.

What is West Nile virus infection?

West Nile virus infection occurs when a person is bitten by an infected mosquito and the virus enters the person’s blood, multiplies, and spreads to other parts of the body. Usually, the body’s immune system can fight off the virus and stop it from causing illness.

What is West Nile virus illness?

Most people who are infected with WNV have no symptoms or may experience mild illness, such as a fever and headache before fully recovering. In some individuals, particularly persons over 50 years of age, West Nile virus can cause serious illness, including encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes covering the brain and spinal cord). Symptoms range from a slight fever, headache, rash, swollen lymph nodes, and nausea to the rapid onset of a severe headache, high fever, stiff neck, disorientation, muscle weakness, and coma. West Nile virus infection can lead to death in 3 to 15 percent of persons with severe forms of the illness.

How do people get West Nile virus?

West Nile virus is spread to humans by the bite of infected mosquitoes, primarily the Culex species commonly found in residential areas. A mosquito is infected by biting a bird that carries the virus. West Nile virus is not spread from person-to-person or from birds to people under normal circumstances.

Have there been any human cases of West Nile virus illness in Connecticut?

Yes, a Fairfield County resident with a mild illness due to WNV infection in 2000 was the first to be identified in Connecticut. Human WNV infections acquired in Connecticut have been identified nearly every year since 2000.

Who is at risk of contracting West Nile virus infection? 

Anyone can acquire WNV infection. Persons who are at highest risk for serious illness are persons over 50 years of age.

If bitten by an infected mosquito, will I get sick?

If bitten by an infected mosquito, your chances of developing illness are less than 1 in 100.

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

Being bitten by an infected mosquito will not necessarily make you sick since most people who are infected with West Nile virus have no symptoms or experience mild illness. When illness occurs, it usually happens 3 to 14 days after being bitten by an infected mosquito.

If bitten, should I be tested?

No. Most mosquitoes are not infected with the West Nile virus. Illnesses related to mosquito bites are rare. However, you should see a doctor immediately if you develop symptoms such as high fever, confusion, muscle weakness, or severe headaches. Patients with mild symptoms are likely to recover completely, and do not require any specific medication or laboratory testing.

Is there a treatment for West Nile virus illness? 

Although there is no specific treatment, the symptoms and complications of the illness can be treated. Most people who get this illness recover from it, although symptoms may last for months, especially in persons who have had encephalitis.

Is there a vaccine for West Nile virus infection?

No vaccine for West Nile virus infection is currently available for use in people. A vaccine is available for horses.

What should I do if I find a dead bird?

From 2000-2005, reports and testing of dead wild birds, primarily crows, was used to help monitor WNV activity in Connecticut. Since 2006, monitoring and risk assessment for WNV has emphasized mosquito trapping and testing results - birds are no longer being collected for testing. They can be placed in a double plastic bag and put out with the trash or brought to a municipal landfill. They can also be disposed of on-site by burying. For avian influenza monitoring, report clusters of dead birds or dead waterfowl and shorebirds to the Department of Energy and Environmental Protection at 860-424-3011 or the Wild Bird Mortality Database.

How should I handle game or wild animals or birds?

In general, when you handle any dead animal, you should try to minimize your potential exposure to infectious diseases (for example, rabies or E. coli infection). There are no special precautions for West Nile virus. When you handle game or wild animals, you should follow these precautions:

• Avoid animals that appear sick or act abnormally.
• Wear disposable rubber gloves (or plastic bags) when dressing and skinning game, and clean up with soap and water promptly.
• When preparing meat for cooking, wash hands and surfaces on which the meat is prepared with soap and water immediately after handling.
• Cook game to 165 degrees Fahrenheit internal temperature by meat thermometer and keep it at 165 degrees for at least 15 seconds.

How can I lower my risk to West Nile virus?
You should try to reduce the risk of being bitten by mosquitoes. If West Nile virus is found in your area, you should:

• Minimize time spent outdoors between dusk and dawn when mosquitoes are most active.
• When it is necessary to be outdoors, use mosquito repellents containing an EPA-registered active ingredient, including DEET, Picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol (PMD), or 2-undecanone. EPA registration of skin-applied repellent products indicates that they have been evaluated and approved for human safety and effectiveness when applied according to instructions on the label.
• Wear shoes, socks, long pants, and a long-sleeved shirt when outdoors for long periods of time, or when mosquitoes are more active. Clothing should be light-colored and loose-fitting and made of tightly woven materials that keep mosquitoes away from the skin.
• Wear clothing and gear treated with permethrin. Permethrin is an insecticide that kills or repels mosquitoes and ticks.
• Be sure door and window screens are tight-fitting and in good repair.
• When sleeping outdoors, use tents or mosquito netting in an unscreened structure. Treat camping gear with permethrin when possible.
• Cover strollers and baby carriers with mosquito nets when outside.

Should I stay indoors if West Nile virus is confirmed in my town?
It is not usually necessary to limit outdoor activities. However, you can and should try to reduce your risk of being bitten by mosquitoes by reducing standing water in your yard and taking personal precautions to prevent mosquito bites.

What is being done in my community to control mosquitoes? 

The State of Connecticut has prepared a plan to address the return of West Nile virus and has devised a preventive strategy to minimize the impact. Local communities are implementing various control measures based on geographic location and level of risk. For more information regarding activities in your specific area, contact your local health department.

What else can I do to reduce the risk of West Nile virus? 

In addition to reducing potential mosquito breeding sites on your own property, you can encourage your neighbors, local businesses, and municipal agencies to do so as well. You can also work with local service, labor, religious, and fraternal organizations to promote community-wide cleanup drives. For more information on how you can help, contact your local health department.

How can I get more information on West Nile virus infection? 

Contact your local health department. For specific questions on human infections, contact the Connecticut Department of Public Health at 860-509-7994. For specific questions on infections in domestic animals, contact the Connecticut Department of Agriculture at 860-713-2505.

Content last updated in September 2024.