Establishment of an experimental field population of Theileria lawrencei-infected ticks maintained by African buffalo (Syncerus Caffer).

A population of Rhipicephalus appendiculatus ticks infected with buffalo-derived Theileria lawrencei was established in a paddock. Two infected buffalo had been introduced into this paddock which contained a small population of Theileria-free R. appendiculatus. At intervals, successive groups of Theileria-susceptible cattle were grazed with the buffalo. Transmission of T. lawrencei from buffalo to cattle was first noted 7 to 8 months after the introduction of the buffalo, this delay being accounted for by the slow buildup of the tick population and low infection rates in ticks. A T. lawrencei challenge lethal for cattle was finally achieved 10 months after the introduction of the buffalo. The paddock was then seeded with engorged R. appendiculatus female ticks and an increase in tick population occurred. The lethal challenge was observed for a further 3 years, death of exposed cattle becoming progressively more rapid as the tick population increased. The T. lawrencei challenge establsihed in the paddock may be suitable for testing the efficacy of various T. lawrencei-immunization procedures for cattle.