Cryptosporidium parvum Oocyst Shedding in Neonatal Calf Diarrhea Syndrome in Southern Taiwan

Abstract

The objective of this study was to investigate the relationship between oocyst shedding of Cryptosporidium parvum and diarrhea in dairy calves in southern Taiwan. A total of 48 neonatal calves from six different farms known to be positive for Cryptosporidium parvum bovine genotype were included in this study. Feces were collected from each calf every three days during their first month of life. The consistency of each fecal sample was noted, and the number of oocysts per gram (OPG) of feces was calculated using modified Ziehel-Neelsen stain (MZN). In addition, a commercial antigen-based ELISA diagnostic kits for C, parvum, rotavirus, coronavirus and E. coil F5 was employed to identify the presence of common enteropathogenic agents in 66 randomly selected diarrheic samples. The results were as the following: Oocysts were detected in the feces of 79.2% (38/48) calves within the first month of life. Oocysts were first detected in 60.5% (23/38) of positive calves at 4 days of age (the time of the second sampling). The highest oocyst detection rate (71.1-78.9%) occurred between 7 and 16 days of age (the third to the sixth sampling). The oocystexcretion period varied from the first to the eighth sampling. Of the 66 diarrhea samples analyzed for the enteropathogenic agents, 6 (9.1%) and 1 (1.5%) were found to have the single pathogen C, parvum and 1 E, coil F5, respectively, and 59 (89.4%) were C, parvum association with rotavirus, coronavirus and/or E, coil. The ratio of diarrheic feces was significantly (P＜0.05) higher on the oocyst initial excretion day compared to oocyst pre-excretion period or oocyst-disappearance period. In addition, more calves became diarrhea during the periods of elevated OPGs, and the occurrence of diarrhea rapidly decreased after the oocyst disappearance in the feces. Based on these findings, we concluded that C. parvum infection plays an important pathogenic role in neonatal calf diarrhea syndrome in southern Taiwan.