July 2, 1998
ENCEPHALITIS VIRUSES IDENTIFIED IN BIRDS
SPRINGFIELD, IL The Illinois Department of Public Health today reported that its early warning system for possible mosquito-borne disease activity has detected evidence of encephalitis in birds in Cook and DuPage counties.
Blood samples from one bird collected on June 3 in central Cook County was positive for St. Louis encephalitis (SLE). Also, one blood sample collected on June 5 from a bird in DuPage County tested positive for eastern equine encephalitis (EEE). No human cases of illness from either virus have yet been reported.
"These positive bird samples are an early warning that encephalitis may become a problem in the area," said Dr. John R. Lumpkin, state public health director. "We do not believe this information indicates a need for undue alarm, but persons particularly those living in the Chicago metropolitan area should increase their awareness, surveillance and prevention activities."
The Department annually collects blood samples from birds to determine if arboviruses are present in an area. Mosquitoes pick up the virus when feeding on infected birds and then pass the infection on to humans when biting.
Thus far in 1998, the Department has collected 1,370 samples from birds in 20 Illinois counties. In addition, the Chicago Department of Public Health has collected samples from 182 birds this year. In 1997, IDPH collected 4,109 samples; only one was positive for EEE. Counties are selected as collection sites based on the history of virus activity in those areas.
Only three cases of SLE have been confirmed in Illinois residents since 1992. There have been no confirmed cases of EEE in humans in Illinois. Doctors, hospitals and local health departments have been notified of the possibility of encephalitis and asked to be alert to persons with symptoms of the viruses.
Two types of encephalitis are most common in Illinois: St. Louis encephalitis, which is more common among older adults, and LaCrosse encephalitis, which generally strikes children. Both illnesses are characterized by similar symptoms, which 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. Symptoms usually appear five to 15 days following the bite of an infected mosquito.
EEE, which is carried by marshland and wetland mosquitoes, is primarily a disease of horses. Although the virus can infect humans, cases are extremely rare only about five are reported annually in the United States.
Dr. Lumpkin emphasized that the first and best defense against mosquitoes and the illnesses they carry is to eliminate the places where they breed. Here are some suggestions:
Personal protection is also important. There are a number of ways people should protect themselves, particularly if they plan to participate in outdoor activities during times when mosquitoes are active.
of Public Health
535 West Jefferson Street
Springfield, Illinois 62761
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