Asymptomatic infection and risk factors for leptospirosis in Nicaragua

As part of an investigation of a 1995 outbreak of leptospirosis in Nicaragua, a cross-sectional serologic survey was conducted in the town of El Sauce. Of 566 persons, 85 (15%) were positive for IgM anti-Leptospira antibodies, indicating recent leptospirosis infection. Asymptomatic leptospirosis infection was common, with only 25 (29.4%) of the 85 seropositive inhabitants reporting a febrile illness in the 2 months before the survey. Multivariable analysis revealed that having an indoor water source remained independently protective against leptospirosis. Gathering wood was independently associated with infection. These findings suggest that asymptomatic infection with Leptospira is common in endemic areas of Leptospira transmission. Improvement in water sanitation and behavioral modifications to reduce environmental exposure may reduce the risk of leptospirosis in endemic regions.