Dynamic changes in the epidemiology of canicola fever in Israel. Natural adaptation of an established serotype to a new reservoir host.

Investigation of human leptospirosis caused by the serotype canicola revealed a significant shift in the chain of infection of this disease. The adaptation of an old and well-established serotype to a new and abundant host, the Norway rat, provides a new means for spreading and transferring canicola fever to man and farm animals. The changes in the epidemiology of leptospirosis described should serve as a warning to epidemiologists responsible for suggesting proper prophylactic measures.