A 10 month old female infant was admitted to the hospital with vomiting for 3 days due to diarrhea. Stool 7-8 times a day, egg flower soup like, slightly fishy, dry mouth less urine for one day. The children were mainly fed with milk. Their parents had poor hygiene habits and less sterilized milk utensils. No previous history of diarrhea. Physical examination: body temperature 38 ℃, poor spirit, less tears when crying, sunken anterior fontanelle and eye socket, dry lips, normal heart and lung. The abdomen is soft and the bowel sounds active. Stool routine: yellow color, mucus, white blood cells 0 ~ 5 / HPThe following factors are related to diarrhea in this case, except