These organisms are antigenically complex, with over 200 known pathogenic serologic variants. Although certain geographic regions contain specific leptospiral serovars and species, the serologic characterization of an isolate is not an absolute predictor of its species designation. However, leptospirosis is no longer a reportable disease in the United States. Although incidence in the United States is relatively low, leptospirosis is considered to be the most widespread zoonotic disease in the world. The clinical course is highly variable.
Transmission Occurs through direct or indirect transmission from a mammalian host.
Indirect transmission via contact with Leptospira contaminated water or soil, is thought to be responsible for most cases. Recreational exposures can include rafting, kayaking, and swimming. To determine the incidence of leptospirosis in high-risk areas, active surveillance will be required. Trends Leptospirosis continues to re-emerge as a notable source of morbidity and mortality in the Western Hemisphere. Significant increases in incidence were also reported from Peru and Ecuador following heavy rainfall and flooding in the spring of 1998.