Theileria mutans: experimental transmission by Haemaphysalis punctata.

T. mutans (Essex), originally isolated from a farm in the County of Essex in South-east England by allowing field-collected H. punctata tickes to feed on a splenectomized calf, was syringe-passaged once between calves and then resecured in a laboratory-reared strain of H. punctata. From subsequent studies it was found that only transstadial transmission of the parasite occurred. Thus, only the larval and the nymphal stages of the ticks were capable of acquiring the infection and subsequently nymphs and adults respectively were capable of transmitting the parasite. It was noted that once infected ticks transmitted T. mutans, the succeeding stages were uninfected. After 7 tick passages between cattle there was no evidence of increasing virulence of the parasite.