Leptospirosis is one of the world’s most widespread zoonotic diseases. Native, feral and domestic animals may serve as reservoirs, with rats and other rodents recognised as the most important maintenance hosts. Leptospirosis affects a range of domestic animals including cattle, pigs, dogs, sheep, horses, goats and deer. Classically the serovar linkages are cattle with serovar Hardjo and pigs with serovars Pomona and Tarrasovi. There is evidence for the infection of sheep, particularly with serovar Hardjo. Infection of horses may occur and dogs are occasionally infected.

The clinical signs of infection can range from inapparent to severe, and be influenced by factors such as species, inoculation dose, immune status and age. Clinical signs may include fever, jaundice, haemoglobinuria, pulmonary congestion and death, and in more chronic infections infertility/reproductive failure/ agalactia.In pigs at slaughter, visible kidney lesions (‘white spotting’) are often used as an indication that a group of pigs carries leptospirosis infection but this is of limited value in identifying infection in individuals.

Leptospirosis is diagnosed by PCR, histology and serology: Fresh urine, body cavity fluid or fresh post mortem tissue (e.g. kidney, liver) and/or serum for serology are useful samples.  Serology indicates whether an animal has been infected in the past. PCR determines if the agent’s genetic material is currently present in the sample.