August 21, 1998
Contact: CDC, Division of Media Relations
(404) 639-3286

Update: Leptospirosis and Unexplained Acute Febrile Illness Among Triathlon Participants

Since July 14, 1998, the Illinois Department of Health, the Wisconsin Department of Health, the U.S. Department of Agriculture, and CDC, in collaboration with other state and local health departments, have been investigating an outbreak of acute febrile illness among athletes from 44 states and seven counties who participated in triathlons in Springfield, Illinois, on June 21, 1988, and in Madison, Wisconsin, on July 5, 1988. The ongoing investigation indicates that Leptospira bacteria were the cause of illness in some athletes and other persons exposed to Lake Springfield, where the Illinois triathlon was held. Illness among persons who participated only in the Wisconsin triathlon has tended to be milder, and so far, these patients have not demonstrated serologic evidence of leptospirosis, although additional testing is needed.

A standardized questionnaire was administered to 1194 persons who participated in one or both events. Of these, 110 (9%) described having an illness meeting the case definition of suspected leptospirosis. Symptoms included chills, headache, myalgia, diarrhea, eye pain, or red eyes. Seventy-three of these persons sought medical care, and 23 of those were hospitalized. Surveillance in the community has identified an additional 228 persons who were exposed to Lake Springfield through work or recreation and who had an illness meeting the case definition.

Serum specimens from athletes and other exposed ill persons are being tested at CDC. At least 30 specimens from athletes participating only in the Illinois triathlon and at least 5 from recreational users of Lake Springfield show laboratory evidence for leptospirosis. No samples from athletes participating only in the Wisconsin triathlon have been positive. For accurate serologic test results, samples should be obtained during both the acute phase and the convalescent phase of illness; therefore, testing is not complete and the total number of persons with serologically confirmed leptospirosis is not known.

On July 24, the Springfield and the Illinois departments of health issued a precautionary advisory not to swim, water ski, or use personal watercraft at Lake Springfield. Investigators from CDC, USDA, and state and local health departments are continuing to try to find additional cases of leptospirosis among triathlon participants and persons exposed to Lake Springfield. They are also seeking to find the cause and mode of transmission of illness among Wisconsin triathlon participants and to develop prevention and control measures for both outbreaks.

Additional information on leptospirosis and on these outbreaks is available in the August 21, 1998, issue of the Morbidity and Mortality Weekly Report, http://www.cdc.gov or on the Division of Bacterial and Mycotic Diseases web site http://www.cdc.gov/ncidod/dbmd/lepto.htm and on CDC's outbreak line at 1-888-688-2732 (1-888-OUTBREAK).

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