ESCHERICHIA-COLI HEAT-STABLE ENTERO-TOXIN IN FECES AND INTESTINES OF CALVES WITH DIARRHEA

  • 1 January 1980
    • journal article
    • research article
    • Vol. 41  (7) , 1143-1149
Abstract
Detection of E. coli heat-stable enterotoxin (ST) in the feces of calves was evaluated as a method for implicating E. coli in neonatal calf diarrhea. Use of the infant mouse test was evaluated for detection of ST in the feces of calves with naturally occurring diarrhea. Simultaneous identification of bovine enteropathogenic strains of E. coli (EEC) and of other infective agents implicated in neonatal calf diarrhea was attempted in these samples. The ST was detected with certainty in 7 of 41 samples from calves .ltoreq. 3 wk old. EEC was detected in 27 samples. In 23 of these 27 samples, EEC was the only recognizable diarrheagenic agent. In a small percentage of the samples, Salmonella, rotavirus, coronavirus and Cryptosporidium were recognized alone, in combination with each other or with EEC. Six calves were fed colostrum from cows inoculated with the bovine EEC strain B44, 6 were given colostrum from cows vaccinated with non-EEC strain 28F and 4 were given milk from non-vaccinated heifers. Two of the calves given colostrum from cows inoculated with strain B44 were challenge exposed with the non-EEC strain 28F. The remaining calves were challenge exposed with the EEC strain B44. Fecal samples were taken from these calves at intervals and were examined for presence of ST and of the challenge-exposure organism. The ST was detected in approximately 1/2 of the fecal samples obtained and it was most often detected in the early stages of the induced diarrhea. Calves shed the challenge-exposure EEC strain for long periods in the absence of diarrhea or detectable amounts of ST in the feces. The ST was detectable in fecal samples when diarrhea was severe and when the dry matter content of the fecal samples was low.