Additional tests including convalescent serology and serotyping are pending. The only common exposure for those patients was on May 6-7 when they rented a houseboat on a reservoir in the Sierras with five other men. While everyone reported swimming in the reservoir, only these three patients swam to a cove and hiked up to a waterfall. Wildlife is common in this area and range cattle were observed grazing above the cove where a tributary drains into the reservoir. DHS will be assisting the local health department with environmental sampling at the cove, including collection of water specimens to test for Leptospira.
Leptospirosis is a bacterial disease that affects humans and animals.
In severe cases, the patient may progress to renal failure, liver failure, respiratory distress, or meningitis. Outbreaks are most frequently associated with exposure to water contaminated with the urine of infected animals such as cattle, pigs, horses, dogs, rodents, and other wildlife. Humans can become infected by swallowing contaminated water or by having contaminated water contact mucous membranes or broken skin. The largest leptospirosis outbreak in the continental U. S. occurred in a group of persons participating in competitive swimming events in the Midwest in 1998 where 110 cases were identified among 775 exposed persons. In California, an average of 1-2 cases of leptospirosis are reported each year.