August 10, 1995
OLSON LAKE TO REMAIN CLOSED FOR REMAINDER OF THE SUMMER
SPRINGFIELD, IL -- The bathing beach at Rock Cut State Park's Olson Lake will stay closed for the remainder of this summer's swimming season to allow the lake to naturally eliminate possible bacterial contamination, Dr. John R. Lumpkin, state public health director, said today.
Twelve children, 2 to 12 years of age, became ill with E. coli 0157:H7 or had symptoms compatible with the bacteria after swimming at Olson Lake on the weekend of June 24 and 25. Three of the children were hospitalized with hemolytic-uremic syndrome, which can result from E. coli 0157:H7 infection.
No additional cases of illness were reported among persons who swam at the lake between June 25 and when the beach was closed July 6 after the swimming associated illnesses were reported.
Dr. Lumpkin said a month-long investigation of the lake's bathing beach and its surrounding environment was unable to pinpoint the source of the E. coli 0157:H7.
But since scientists believe the bacteria can live in water for up to two months, Dr. Lumpkin recommended to the Illinois Department of Natural Resources (DNR), which operates the bathing beach, that Olson Lake not reopen this swimming season.
The beach normally is open through Labor Day. DNR has agreed with the recommendation.
"Because this bacteria can live in water for a long period of time, in the interest of public safety we have urged that the bathing beach stay closed until next year's swimming season," Dr. Lumpkin said. "Over the next nine months we will review our beach regulations and procedures to see what may be necessary to deal with the threat of E. coli 0157:H7 in natural bodies of water."
"The Department of Natural Resources will continue to do everything it can to assist in this investigation," said Brent Manning, DNR director. "The health and safety of park visitors remains our primary concern."
Dr. Lumpkin said, that based on the experiences with similar outbreaks at bathing beaches in New York and Oregon, the natural cleansing of the lake water between now and next May should allow the lake to be reopened to swimmers in 1996.
Department of Public Health investigators believe the most likely source of the E. coli 0157:H7 pathogen was fecal pollution by bathers, some of whom were toddlers not yet toilet trained, who accidently or deliberately defecated in the lake. A single bowel movement from an infected person could probably release millions of E. coli 0157:H7 bacteria into the water; it is believed that a person only needs to swallow a small number of bacteria to become ill.
As part of the investigation, Department environmental engineers collected numerous water samples, surveyed the recreation area's toilet and shower facilities for sewage leaks, sampled the beach's drinking water, reviewed concession stand operations, and surveyed the lake's watershed for possible sources of fecal contamination, including septic systems and animal feed lots. The park facilities were found to be well maintained, no sewage leaks were detected and no potential problems were identified in the lake's watershed.
Department communicable disease staff tested samples of droppings from geese, ducks and other waterfowl for evidence of E. coli 0157:H7, contacted campers at Rock Cut State Park to determine if others who used the beach may have been ill, questioned those who became ill about what they did at the beach and whether they swallowed lake water, and compared those who became ill with a control group of people who used the beach but did not get sick to determine if there were other possible explanations for the illness.
All test results of water samples and bird droppings were negative for E. coli 0157:H7 and the only factor consistently associated with those who were ill was swimming at the beach and swallowing the water.
E. coli 0157:H7 is a relatively new disease-causing organism, first identified in 1982 and most often associated with undercooked hamburger. It has been linked to swimming in fecal-contaminated water in two other outbreaks in the United States.
E. coli 0157:H7 can cause severe illness, particularly among children younger than 5 years of age and the elderly.
of Public Health
535 West Jefferson Street
Springfield, Illinois 62761
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