3. Results
3.1. Occurrence of Enteric Pathogens inIll Calves during the Outbreak
In the initial EIA analysis of major enteric pathogens in the 18 specimens from ill calves, 10 were positive for Cryptosporidiumspp., five for rotavirus, one for coronavirus, and none for enteropathogenic E. coli . All five rotavirus-positive specimens were also positive for Cryptosporidium spp. (Table 2). These 18 specimens were further analyzed for Cryptosporidium spp. using the SSU rRNA-based PCR, leading to the identification of C. parvum in 10 of them, including 9 of the 10 EIA-positive specimens. All the C. parvum -positive specimens were successfully subtyped as IIdA20G1 by sequence analysis of the gp60 gene.
3.2. Occurrence of Rotavirus inNeonatal (1-4-Week-Old) Calves
During the outbreak, 8/37 (21.6%) specimens from neonatal calves were positive for rotavirus. In contrast, 7/38 (18.4%) specimens from neonatal calves were positive after the outbreak (Fig. 2). Altogether, 15 of the 75 fecal specimens from neonatal calves of 1 - 4 weeks were positive for rotavirus by EIA. Among them, the infection rate was 21.1% (8/38) in calves with watery diarrhea, 0% (0/6) in calves with moderate diarrhea, and 22.6% (7/31) in calves without diarrhea (χ2 = 1.66, df = 2, P = 0.437).