Shedding ofCryptosporidiumin calves and dams: evidence of re-infection and shedding of differentgp60subtypes

Abstract

AbstractOne of the most common causes of calf diarrhoea is the parasiteCryptosporidium parvum.Two longitudinal studies were carried out on a dairy farm Scotland to determine the prevalence ofCryptosporidiumspecies and subtypes in a group of calves and to determine whether dams were a possible source of calfhood infection. Fecal samples were collected from 25 calves from birth to 12 months in the first year. In the second year, fecal samples were collected from pregnant cows (n= 29) and their calves (n= 30) from birth to 6 months. The samples were tested forCryptosporidiumand speciated.Cryptosporidium parvum-positive samples were subtyped by GP60 fragment analysis. All calves in both studies shedCryptosporidiumduring the study period.Cryptosporidium parvumwas the predominant species detected in calves ⩽6 weeks of age and at 6 months of age,C. bovisandC. ryanaewere detected in calves older than 4 weeks of age but ⩽6 months of age. The prevalence ofCryptosporidiumwas higher in younger animals than in older animals. GP60 subtyping revealed two subtypes in calves on this farm (IIaA15G2R1 and IIaA19G2R1) that differed in frequency by age. Adult cattle also shedC. parvum,of fourgp60genotypes.