Blood samples being collected from each of 210 head of cattle previously vaccinated against tickborne diseases. This herd is on a commercial farm in the Norton area of Zimbabwe. Veterinary department technicians bleed cattle under the supervision of an FA - - Integrated Tickborne Diseases Control Project: GCP/ZIM/014-015 (DEN-BEL). The object of this project is the protection of cattle by vaccinating against Theileria parva infection, a tick borne disease locally termed January Disease or Tobacco Disease.Vaccination is carried out using I parva boleni Bolvac, a locally produced vacc