What kinds of diseases can be carried by mosquitoes?
Mosquito-borne disease is rare in Illinois. However, mosquitoes can carry at least three encephalitis viruses that cause human disease. La Crosse (California) encephalitis is normally an infection of squirrels and chipmunks; in humans it affects mainly children. St. Louis encephalitis is an infection of wild birds; in humans it affects mainly older adults. In 2001, West Nile virus (WNV) was detected for the first time in Illinois in birds, horses and mosquitoes. West Nile virus, like St. Louis encephalitis, causes encephalitis primarily in older adults.
What is encephalitis?
Encephalitis is an inflammation of the brain that can be caused by arboviruses (viruses carried by arthropods, such as mosquitoes and ticks) or by other types of viruses. In Illinois, arboviruses are primarily transmitted to humans by the bites of infected mosquitoes. Most individuals who are bitten by an infected mosquito will experience no symptoms of the disease or will have only very mild symptoms. Approximately 1 percent to 2 percent will develop recognizable symptoms. Some persons may have mild symptoms, such as a fever and headache. Severe infection may cause rapid onset of severe headache, high fever, muscle aches, stiffness in the back of the neck, problems with muscle coordination, disorientation, convulsions and coma. Symptoms usually occur five to 15 days after the bite of an infected mosquito. Not all viruses that cause encephalitis are carried by mosquitoes.
How can I help protect my family and myself from mosquitoes and the diseases they may carry?
During the summer, mosquitoes can develop in any standing water that lasts more than seven to 10 days. Consequently, you can begin protecting your family from mosquitoes by reducing the amount of standing water available for mosquito breeding around your home:
Should we stay indoors?
It is not necessary to limit outdoor activities unless there is evidence of mosquito-borne disease in your area. However, you can and should try to reduce the risk of being bitten by mosquitoes.
Can pets and livestock get WNV infection?
Horses can become infected with WNV if bitten by mosquitoes that carry the virus. There is a published report of West Nile virus isolated from a dog in southern Africa (Botswana) in 1982. West Nile virus has been isolated from several dead cats in 1999 and 2000. A blood of dogs and cats in the epidemic area showed a low infection rate.
What signs of infection should I look for in domestic animals?
West Nile virus and other mosquito-borne viruses can cause encephalitis in domestic animals. Sick animals may have a fever, weakness, poor muscle coordination, muscle spasms and signs of a neurological disease, such as change in temperament or seizures.
What should I do if I suspect my pet has WNV?
If your animal is sick, contact your veterinarian. The veterinarian will evaluate your animal, provide treatment and forward samples for laboratory testing to rule out other possible diseases. The Illinois Department of Agriculture can help veterinarians determine if WNV is the cause once the illness is reported.
Can you get WNV directly from birds, game or domestic animals?
The risk to humans and domestic animals is from the bite of WNV-infected mosquitoes. Although there is no evidence of human infection from handling infected live or dead animals, the U.S. Centers for Disease Control and Prevention recommends that anyone handling sick or dead animals avoid bare-handed contact. Hunters should use gloves when cleaning game animals and persons disposing of dead birds should use a shovel, gloves or double plastic bags to place carcasses in a garbage can. After disposing of the carcass, thoroughly wash your hands with soap and warm water. Veterinarians should use normal veterinary infection control precautions when caring for a horse suspected to have this or any other infection.
Is there a vaccine for pets and livestock for WNV?
A vaccine is available to protect horses from WNV infection; vaccines for other domestic animals are not available currently.
How is WNV infection in domestic animals treated?
As in people, there are no specific treatments for WNV infection in domestic animals. Treatment is primarily supportive to lessen the severity of the symptoms.
How can I protect pets and livestock from WNV infection?
You can reduce the risk of WNV infection in animals by minimizing their exposure to infected mosquitoes.
Where can I get more information on WNV?
Call your local health department or the Illinois Department of Public Health at the telephone numbers listed below. Or visit the Department's Web site, <www.idph.state.il.us> and the U.S. Centers for Disease Control and Prevention's West Nile virus site at < http://www.cdc.gov/ncidod/dvbid/westnile/index.htm>.