SURVEY ON THE PREVALENCE OF LEPTOSPIRA INFECTIONS IN THE ITALIAN POPULATION

This investigation is the first nationwide survey on the circulation o f leptospira infections in human beings in Italy. In nine out of twent y Italian regions, representative samples of the population were inves tigated for the presence of leptospira infections. Unexpectedly, lepto spira infections were found to be widespread, the number of cases bein g much higher than the diagnosed clinical cases. There were found to b e high, medium, and low risk areas. On the whole, the risk for the rur al population was no higher than the risk for urban dwellers; leisure activities, contact with animals and residence on the plain versus res idence in the hills were important risk factors. There was an unidenti fied risk factor in urbanites which was absent in the rural population . A changing pattern in infecting serovars was observed, with infectio ns from serogroups Sejroe, Javanica and Australis prevailing over infe ctions from the Icterohaemorrhagiae and Bataviae sero-groups, which we re the main agents of human leptospirosis during the 1950s. The mechan isms of these changes, the need for epidemiological surveys and improv ed diagnostic methods of screening are discussed.