Although it produces little evidence of clinical disease, serological surveys have suggested that this serovar is widespread in Alberta. Another serovar, L. pomona , for which the definitive host is swine. has also been recognized on a number of occasions as a cause of abortion in both cattle and swine. Blood testing indicates that a number of other serovars such as L. icterohaemorrhagiae are also present, but they are rarely directly involved in disease outbreaks. Spread Leptospirosis usually gains access to a herd by means of an infected carrier animal or infected wildlife. Alternatively, aborted fetuses, afterbirth or uterine discharges can contaminate the environment.
Infected bulls can also transmit the infection through semen to females in the herd.
Infected swine have been known to pass the organism in their urine for up to two years. These long term shedders are of particular importance because they transmit the disease to younger animals in the herd or, if sold, transmit it to the purchaser's herd. The organism can survive for up to six months in moist, warm conditions. Stagnant water is an ideal source of infection. For these reasons, leptospirosis is seen most frequently in areas of the world that have a temperate climate and a high rainfall.