Relative infectivity of Theileria annulata (Dchunkovsky and Luhs, 1904) stabilates derived from female and male Hyalomma excavatum (Koch, 1844) ticks.

Partially engorged female and male Hyalomma excavatum ticks infected with Theileria annulata were triturated separately in Eagle's minimum essential medium complemented with fetal calf serum. Glycerol was added to the supernatant obtained after centrifugation and the material was frozen at -79 degrees C. Infectivity of the stabilate was titrated by inoculating susceptible calves with dilutions of the material. Stabilate prepared from female ticks was considerably more infective on a per tick basis than stabilate from males. All calves inoculated with an estimated equivalent of 0.1 or more female ticks, or 3.3 or more male ticks, became infected. Time to fever, prepatent period, and mortality did not appear to be dose-dependent in the range of tick equivalents employed.