Leptospirosis

Leptospirosis cases under investigation

Three men from the SF Bay Area were diagnosed with leptospirosis last week. The men were all in their 30's and were previously healthy. Their symptoms began May 16-17 with fever, headache, and myalgias. One patient developed hepatitis and another renal failure; two were hospitalized. Leptospira-specific IgM was positive in 2 of the 3 patients; the 3rd patient's serum may have been collected too early in the course of the disease to turn positive. 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. The incubation period is commonly about 10 days (range, 2 days to 4 weeks). Symptoms can include flu-like illness (high fever, headache, chills, muscle aches), jaundice, conjunctivitis, abdominal pain, vomiting, diarrhea, and sometimes a rash. In severe cases, the patient may progress to renal failure, liver failure, respiratory distress, or meningitis.

Leptospirosis can be treated with a variety of antibiotics, but the latest (year 2000) edition of Medical Letter still recommends penicillin as the drug of first choice. 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. Certain occupations (e.g., farmers, veterinarians, sewage workers, etc.) put persons at increased risk of exposure to Leptospira; for them, protective clothing and footwear are advised.

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. In 1997, there were 12 cases reported to DHS including several linked to an outbreak in Costa Rica following a rafting trip.