Three case studies involving Leptospira interrogans serovar pomona infection in mixed farming units

Three case studies involving Leptospira interrogans serovar pomona outbreak s within mixed farming systems in South Africa are described. On 2 farms, p igs constituted the main enterprise with cattle and sheep of secondary impo rtance. On each of these 2 farms, abortion due to L. pomona in sows was con firmed by culture, and antibody titres to pomona were detected in cattle, s heep, horses and dogs. On the 3rd farm, a piggery was of secondary importan ce to cattle farming. Abortion and death in cows occurred on this farm and serology showed titres to various serovars, including pomona. L. pomona was also isolated from bovine urine, an aborted bovine foetus and kidneys from slaughtered pigs. This particular case study was regarded as clinically at ypical in that adult Jersey cattle died of acute leptospirosis in a semiari d region of South Africa. In all 3 case studies, the poor management of pig effluent and of the drinking water and its sources played a pivotal role i n the transmission of the disease. Inadequate vaccination of animals agains t Leptospira and poor record-keeping within the secondary farming enterpris es were also contributing factors to the spread of leptospirosis.