AN OUTBREAK OF BOVINE ABORTIONS ASSOCIATED WITH LEPTOSPIROSIS

A severe abortion storm on a grazing property, in which 50% of Hereford cows aborted in 2 months, is described. Serological evidence suggested that the abortion storm was due to leptospirosis. Epidemiological factors associated with the abortion storm were (a) introduction of infected cows into a susceptible population; (b) the practice of seasonal calving, which resulted in the susceptible population being in the last third of gestation when exposed to infection; and (c) environmental conditions suitable for the propagation of leptospira being coincident with the introduction of infection into the susceptible herd.