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Leptospirosis is a zoonotic disease caused by the bacteria Leptospira interrogans. Leptospirosis occurs worldwide, and is more common in temperate and tropical areas. Approximately 100 to 200 cases are identified annually in the United States, of which half are reported in Hawaii. Some wild and domestic animals, such as rodents, raccoons, cattle, pigs, and dogs carry the Leptospira bacteria and pass them in their urine.

Exposure occurs when water contaminated with the urine of infected animals is ingested or comes into contact with mucous membranes or breaks in the skin. People are often exposed through recreational activities such as swimming, canoeing, or participating in open water events such as triathlons or adventure travel. Leptospirosis is rarely spread from person to person.

Occupations at greater risk include farmers, rice and sugarcane field workers, miners, slaughterhouse workers, sewer workers, and veterinarians. Non-severe cases of leptospirosis are likely under-recognized and under-reported.


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