Leptospiral infections of rodents in the North Island

162 rodents, largely from dairy farms in Taranaki and the Waikato, were examined for evidence of leptospiral infection. 33 (20%) revealed cultural and/or serological evidence of leptospiral infection. L. ballum was isolated from the kidneys of Rattus norvegicus, R. rattus and Mus musculus collected in Northland, the Hauraki Plains, and in southern Taranaki. L. copenhageni was isolated from the kidneys of R. norvegicus collected in rural rubbish tips near Tirau and Morrinsville. No evidence of L. hardjo or L. pomona infections were found among the rodents. Factors contributing to the distribution and incidence of leptospiral infections among rodents, cattle and humans are discussed.