August 9, 1996

MOSQUITO-BORNE DISEASE REPORTED IN ROCK ISLAND COUNTY

SPRINGFIELD, IL -- A 13-year-old girl from Rock Island County has been diagnosed with the state's first case this year of a mosquito-borne disease, the Illinois Department of Public Health reported today.

Identification of the disease, LaCrosse (California) encephalitis, was confirmed August 8 by the Department's laboratory. The youth became ill July 1, was hospitalized and has now recovered.

Mosquitoes that transmit LaCrosse encephalitis and St. Louis encephalitis, another mosquito-borne disease, 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.

"It is important for people to take precautions around their homes and eliminate places where mosquitoes 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.
• Inspect door and window screens to ensure they are tight-fitting and in good repair to prevent mosquitoes from entering.
• 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.

"If two or more of these symptoms appear, contact a physician immediately, and inform the doctor of any recent mosquito bites," Dr. Lumpkin said.

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.

Last year in Illinois, there were six confirmed cases of LaCrosse encephalitis and one cases of St. Louis encephalitis. 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.

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