<prompt> All of the following statements about El-Tor vibrios are true, Except -Humans are the only reservoirCan survive in ice cold water for 2-4 weeksKilled by boiling for 30 secondsEnterotoxin can have direct effects on other tissues besides intestinal epithelial cells  <response>: Ans. is d i.e., Enterotoxin can have direct effect on other tissues besides intestinal epithelial cells Cholera exotoxin enterotoxin affects only intestinal epithelial cells. Cholera exotoxin has no effects on any other tissues except intestinal epithelial cells. There is no evidence the V. cholerae invades any tissue nor the enterotoxin to have any direct effect on any organ other than the small intestine. The human is the only reservoir of cholera infection, which may be a case or carrier. There is no known animal reservoir. V. cholerae are killed within a few seconds by boiling. cholerae can survive in ice cold water for 2 - 4 weeks. They remain in ice for 4 - 6 weeks or longer. 