Epidemiology of leptospirosis. Carrier animals, domestic or wild, cycle leptospires within the population. Leptospires may then be transmitted to humans directly by contact with infected urine or indirectly via contaminated soil or water, especially in times of flood. Human leptospirosis constitutes a dead-end infection; human to human transmission is virtually unknown.
Victoriano et al. BMC Infectious Diseases 2009 9:147 doi:10.1186/1471-2334-9-147