An observational analytical epidemiologic study was carried out to identify factors associated with the risk of
infection with Cryptosporidium parvum in dairy herds in southeastern New York state. A random sample of 2943 cattle on 109 farms was selected from the target population. Fecal samples were collected from animals in three different age groups and examined for the presence of C. parvum using a quantitative centrifugation concentration flotation method. Data on intrinsic, preweaning, postweaning, maternity, and general management factors were collected and evaluated for their association with the risk of
infection with C. parvum. Indices for each of these categories of management were developed from factors significantly associated with the risk of
infection with C. parvum. Significant factors were identified using the logistic regression statistical technique. A final analysis, including the indices, age, and season, was performed to identify factors significantly associated with the risk of
infection with C. parvum while simultaneously controlling for the effect of other factors. The farm effect was evaluated using a mixed effect model. Preweaning factors found to be significantly associated with a decreased risk of
infection were: use of ventilation in calf rearing areas, daily addition of bedding, feeding of milk replacer, daily disposal and cleaning of bedding, and use of
antibiotics. Postweaning factors such as moving of the animals after weaning, cleaning of soiled bedding, and use of
antibiotics and
ionophores as preventive measures were significantly associated with the decreased risk of an
infection with C. parvum. Consideration of maternity management factors showed that winter housing of cows individually within 2 months of calving, use of fresh colostrum to feed calves, and having a concrete floor in the calving area were significantly associated with decreased risk of C. parvum
infection. The total number of dairy cattle, total number of other species of agricultural animals on the farm, and the distance of the barn water source from the septic system were found to be significantly associated with increased risk of C. parvum
infection. In the final analysis, the risk of
infection with C. parvum was significantly decreased with an increased value of the maternity management index score. The general management significantly affected the risk of
infection with C. parvum where the risk increased with the increase of the value of the index. The risk of
infection significantly decreased with increase in the age of the animal.