Babesia bigemina in ticks grown on non-bovine hosts and its transmission to these hosts

The failure of Boophilus microplus to be cleansed of Babesia bigemina while the ticks were growing on non-bovine hosts, as well as the infection of the non-bovine hosts, was demonstrated in experiments in which infected ticks were released on a number of sheep, a goat and a horse. Seven of ten batches of ticks, collected from six non-bovine hosts, retained their babesia-infection. Blood subinoculated into cattle from seven of nine sheep and from the horse showed that these animals carried B. bigemina whilst the ticks were feeding on them. This suggested that ticks may have become reinfected from the non-bovine hosts, a possibility supported by the finding of B. bigemina in blood smears from two of the sheep. This work was performed at the Animal Research Institute, Yeerongpilly, and in the Department of Parasitology, University of Queensland, and supported by funds from both organizations. I am indebted to Mr G. D. Daly for technical assistance, to Professor J. F. A. Sprent and Dr H. M. D. Hoyte for their interest and help.