A study of nephritis of beef cattle in North Queensland

The incidence of subclinical nephritis in beef cattle slaughtered at a Townsville abattoir during the period 1970-73 was 3.8 percent. A rising incidence coincided with the wet summer of 1973-74 reaching a peak of 8.2 percent thereafter in June 1974. All but 1 of 100 cases macroscopically identified as nephritis and studied histologically proved to be of interstitial type in which lymphocytic infiltration predominated. Follicular lymphoid hyperplasia was also a common feature. The exceptional case showed proliferative glomerulonephritis. Leptospires were isolated from 16 percent of cases cultured, and observed in 8 percent of specimens examined histologically. All of the 8 isolates subjected to serogrouping were L. pomona. Of the animals tested serologically against 2 serotypes 66.2 percent were positive to L. pomona (33.8 percent), L. hardjo (18.9 percent) or both (13.5 percent). The total incidence is significantly higher than in other random surveys carried out in the region. These findings suggest that Leptospira sp. are a major cause of bovine nephritis. Since other pathogens endemic in the area, for example, Babesia and Theileria sp., may be capable of causing nephritis in cattle an accurate assessment of the aetiology of that form of renal disease in north Queensland cannot yet be made.