Mastitis and abortion in dairy cattle associated with Leptospira of the serotype hardjo.

Following a sudden drop in milk yield in a large dairy herd, leptospiral mastitis due to serotype hardjo was diagnosed serologically and by isolation of the organism from the milk and urine of affected cows. Two milkers subsequently became ill and developed titres to the Hebdomadis serogroup. During the same period the neighbouring herd experienced poor milking performance and a series of abortions and serological evidence suggested recent hardjo infection. The common source of infection appeared to be infected down calving heifers.