Attempted transmission of Babesia major by Boophilus microplus.

Two experiments was carried out to determine if Babesia major could be transmitted by Boophilus microplus. In experiment 1, a Babesia-free batch of laboratory reared Bo. microplus larvae were applied to an intact calf infected by inoculation with a B. major stabilate. The calf showed a B. major parasitaemia while the larvae, nymphs and adult ticks were engorging. The engorged females were cultured and batches were incubated at one of the three following temperatures: 24, 28 or 32 degrees C. Approximately 10,000 larvae derived from each of the females were used to infest each of three splenectomized calves. In experiment 2, Babesia-free Bo. microplus larvae were applied to a splenectomized calf; the calf was injected with B. major stabilate and showed a B. major parasitaemia during the adult stage of tick development. The engorged females were incubated at room temperature and the resulting larvae (approximately 10,000) were used to infest a splenectomized calf. Examination of blood films for the presence of B. major from the four calves infested by the second generation larvae in the two experiments were negative.