August 14, 1996

MOSQUITO-BORNE DISEASE REPORTED IN PEORIA COUNTY

SPRINGFIELD, IL -- The Illinois Department of Public Health today reported that a 12-year-old boy from Peoria County has been identified as the second Illinois resident to be diagnosed this summer with a mosquito-borne disease.

Confirmation of the disease, LaCrosse (California) encephalitis, was made August 13 by the Department's laboratory. The youth became ill July 17, was hospitalized and is now recovering at home.

The state's first case, also LaCrosse encephalitis, was a 13-year-old girl from Rock Island County who became ill July 1. Laboratory confirmation of the disease was made August 8.

Last year in Illinois, there were six confirmed cases of LaCrosse encephalitis and one case of St. Louis encephalitis, another mosquito-borne disease. The LaCrosse encephalitis cases were reported in Boone, Bureau, Effingham, Hancock, LaSalle and McDonough counties. The St. Louis encephalitis case was reported in Cook County.

Although there were no cases reported in Peoria County in 1995, there were four reported in the county in 1994, one in 1993, two in 1992 and two in 1991.

Mosquitoes that transmit LaCrosse encephalitis and St. Louis encephalitis breed in small, stagnant pools of water. Removing receptacles, such as old tires, tin cans, birdbaths and yard ornaments, is the best way to prevent the disease. These mosquitoes also lay eggs in water holes in trees and low-lying areas in the ground.

"People should take precautions around their homes and eliminate places where mosquitoes tend to breed," said Dr. John R. Lumpkin, state public health director.

Dr. Lumpkin said householders also should --

• Keep yard ornaments empty of water.
• Drain or fill low spots in the ground.
• Keep drainage ditches cleared of brush and other excess vegetation.
• Use mosquito repellent when outdoors, applied sparingly to exposed skin or clothing, as indicated on the repellent label.
• Avoid exposure to mosquitoes during the times they usually bite: from dusk to dawn to avoid St. Louis encephalitis, and during daylight hours in wooded or heavily shaded areas to avoid LaCrosse encephalitis.

LaCrosse and St. Louis encephalitis are serious diseases that affect the brain. LaCrosse encephalitis occurs more often in children, while St. Louis encephalitis is more common among adults. Most patients recover fully, although some may have permanent neurological damage.

Symptoms of both diseases are similar and usually begin five to 15 days following the bite of an infected mosquito. The symptoms range from a slight fever or headache to rapid onset of severe headache, high fever, muscle aches, stiffness in the back of the neck and disorientation.

Dr. Lumpkin said if two or more of these symptoms appear, a physician should be contacted immediately and the doctor told of any recent mosquito bites.

Different types of mosquitoes transmit LaCrosse and St. Louis encephalitis and can be distinguished by their feeding habits. The tree-hole mosquitoes that transmit LaCrosse encephalitis bite during daylight hours in or near shaded or wooded areas, while the house (Culex) mosquito that transmits the St. Louis encephalitis virus bites from dusk to daylight.

The tree-hole mosquito is infected with the LaCrosse encephalitis virus by feeding on infected chipmunks, squirrels and other small woodland mammals, which are the carriers of the virus. The house mosquito is infected with St. Louis encephalitis by feeding on birds carrying the virus.

Illinois Department of Public Health 535 West Jefferson Street Springfield, Illinois 62761 Phone 217-782-4977 Fax 217-782-3987 TTY 800-547-0466 Questions or Comments