A Cross-Sectional Study of prevalence and Species of Cryptosporidium spp. in Preweaned Calves and Associated Management Risk Factors on Dairies in Central California, USA - Abstract
Cryptosporidium spp. are major protozoal parasites infecting dairy cattle and cryptosporidiosis is a leading cause of morbidity in dairy calves. The objective of this study was to determine the prevalence and intensity of Cryptosporidium spp. infections associated with farm management risk factors and genotypes of Cryptosporidium spp. in preweaned dairy calves by conducting a cross-sectional study on eight dairies in the San Joaquin Valley of California. Fecal samples were collected from preweaned calves and evaluated for oocysts shedding load using immune fluorescent assay, and genotype using PCR and sequencing of a fragment of 18S rRNA gene. Information on management factors that contained categories of questions related to calf housing, feeding and management were also collected from the study farms. Statistical analysis of variables associated with Cryptosporidium spp. shedding was conducted using a multivariable logistic regression model.The overall prevalence of Cryptosporidium spp. in preweaned calves across all dairies was 56.0% [342/610]. Among 105 isolates of Cryptosporidium spp. successfully genotyped, 86.7% were determined to be C. parvum, 12.4% as C. bovis, and 0.9% as C. ryanae respectively. Calves shedding Cryptosporidium spp. Oocysts had 1.6 times the odds of being 16-31 days of age on the day of sampling compared to other age groups. A Cryptosporidium spp. positive calf had 8.3times higher odds of exposure to milk bottles cleaned 2 to 3times/week compared to negative calves that were exposed to bottles cleaned at every feeding. Positive calves also had 2.4 higher odds of exposure to bottles cleaned exclusively with disinfectant compared to bottles cleaned with disinfectant and water than negative calves. Cleaning bottles with only hot water was found to be protective against Cryptosporidium spp. shedding in calves compared to bottles cleaned with both water and disinfectant. Results of this study provided updated information on Cryptosporidium spp. genotypes infecting preweaned calves on California dairies and approaches to reducing oocysts shedding in calves.