The morphometrics of Babesia motasi (Wales) and its transmission by Haemaphysalis punctata (Canestrini and Fanzago 1877) to sheep.

Babesia motasi (Wales) was transmitted to sheep by larvae, nymphs and adult female Haemaphysalis punctata ticks which were either collected from rough grazing pasture, at Mynydd Mawr, Aberdaron, North Wales, or from laboratory cultures derived from ticks collected at the above site. Both transovarial and transstadial transmission of infection were demonstrated. Only larvae were shown to pick up infection. The parasite could not be demonstrated in intact sheep, either in blood films or following passage of whole blood from intact into splenectomised sheep. Organisms were detectable only in peripheral blood following blood transmission between splenectomised animals or in splenectomised sheep which were tick-infested. In such sheep a parasitaemia occurred 8-9 days after infected ticks started to feed and was accompanied by a mild fever. Splenectomised animals which recovered from acute infection remained as subclinical carriers but infection was eliminated with Ludobal, rendering animals resusceptible to infection. Morphological studies indicated that B. motasi (Wales) is similar to descriptions of isolates in Sweden, Holland and W. Germany but unlike an isolate from Turkey. The most common form is is a double pyriform with a mean length of 2.234 micron.