Prevalence, Genotyping and Pathogenic Role of Cattle Cryptosporidium Infection in Southern Taiwan.

• Main Authors: Chu-Yu Tseng, 曾巨羽
• Other Authors: Yeong-Huey Wu
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/86102609050397035386

碩士 === 國立屏東科技大學 === 獸醫學系所 === 96 === To evaluate the incidence of Cryptosporidium infection in dairy herds in Taiwan, feces of 228 cattles from 24 farms in three counties of southern Taiwan were examined by modified Ziehel-Neelsen stain (MZN) and nested polymerase chain reaction (nested PCR) for Cryptosporidium oocyst from August 2006 to January 2007. Any of the seven nested PCR positive samples collected from seven MZN positive farms were sequenced and compared with the genotypes of Cryptosporidium reported in Genbank. The results show that the detection rate of Cryptosporidium infection was 28.9 % (66/228) by nested PCR, which is significantly (P<0.05) higher than MZN (7.0%, 16/228). Farm positive rates were 62.5 % (15/24) by nested PCR and 37.5 % (9/24) by MZN. Cattle positive rates were 28.9 % (66/228) by nested PCR and 7.0 % (16/228) by MZN, respectively. No significant differences of farm positive rate and cattle positive rate ware found among three counties of southern Taiwan, but infection rate in the group of under-one-month old calves was significantly (P<0.05) higher than other elderly groups. The positive rate of Cryptosporidium infection in the diarrheic cattles was significantly (P<0.05) higher than that in the non-diarrheic cattles. The diarrheic rate of Cryptosporidium oocyst positive cattles was also significantly (P<0.05) higher than that of Cryptosporidium oocyst negative cattles. The similarity of nucleotide sequences between seven nested PCR positive products and Cryptosporidium parvum bovine genotype in GenBank is 96.0-99.6 %. Next, to evaluate the pathogenic role of Cryptosporidium in calf diarrhea, a total of 48 neonatal calves from six MZN positive farms with 8 calves per farm were continuously calculated the oocyst per gram (OPG) by MZN three days interval during the first month age after calving. The consistency of feces was recorded, and the commercial Ag-detection-ELISA diagnostic kit for Cryptosporidium parvum, Rotavirus, Coronavirus and E. coli F5 was used to examine the diarrheic feces. The results show that the C. parvum infection mixed with Rotavirus, Coronavirus and/or E. coli F5 was 87.9 % (58/66), and only 7.6 % (5/66) was purely C. parvum infection. Watery diarrheic feces were always seen following with the rapid increase of the OPG. Fecal consistency always changed with the level of OPG. The feces always convert to normal consistency following the disappearance of oocyst. Then we concluded that Cryptosporidium infection plays a very important pathogenic role in calf diarrhea in Taiwan.