title: Age resistance to Theileria parva bovis infection in calves.
abstract: Data collected in the Zimbabwean province of Mashonaland-West, in the period 1980-1988, showed that mortality in calves owing to Theileria parva bovis infection (January disease) was significantly lower in animals younger than 7 months than in older cattle. Groups of seven Holstein-Friesian calves from non-immune dams aged approximately 1, 4, 7, 10 and 13 months were infected with a Theileria parva bovis tick-derived stabilate. The dose chosen was lethal for 40% of the calves in the trial. Mortality was highest in the 4-month age group. The reactions in the 7-, 10- and 13-month age groups became progressively milder. The reactions in the 1-month old calves were the least marked, being very mild. The age-related resistance in the youngest calves, as can be concluded from our results, is only of short duration and cannot explain the lower incidence of January disease observed in calves in the field.
authors: Veterinary Research Laboratory, Harare, Zimbabwe.
authors: H T
authors: HT
authors: Koch
authors: L
authors: L
authors: Kambeva
authors: R A
authors: RA
authors: Norval
authors: J G
authors: JG
authors: Ocama
authors: S
authors: S
authors: Masaka
authors: F C
authors: FC
authors: Munatswa
authors: N
authors: N
authors: Honhold
authors: A D
authors: AD
authors: Irvin
mesh_terms: D000375:Aging / Q000276:immunology*; D000818:Animals; D002417:Cattle; D004196:Disease Outbreaks / Q000662:veterinary; D005260:Female; D015994:Incidence; D008297:Male; D012044:Regression Analysis; D013801:Theileriasis / Q000453:epidemiology / Q000276:immunology* / Q000401:mortality; D014886:Weaning; D015030:Zimbabwe / Q000453:epidemiology