Update: outbreak of acute febrile illness among athletes participating in Eco-Challenge-Sabah 2000--Borneo, Malaysia, 2000.

During September 7-11, 2000, CDC was notified by the Idaho Department of Health, the Los Angeles County Department of Health Services, and the GeoSentinel Global Surveillance Network of at least 20 cases of acute febrile illness in three countries; all ill patients had participated in the Eco-Challenge-Sabah 2000 multisport expedition race in Borneo, Malaysia, during August 21-September 3, 2000. Participants included athletes from 29 U.S. states and 26 countries. This report updates the ongoing investigation of this outbreak through December 2, which suggests that Leptospira were the cause of illness and that water from the Segama River was the primary source of infection. Participants in adventure sports and exotic tourism should be aware of potential exposure to unusual and emerging infectious agents.