Fall diarrhea is a viral infection. The virus looks like a wheel under an electron microscope, hence the name rotavirus. The virus invades the mucosal cells of the small intestine, causing these cells to lose their ability to absorb water and electrolytes from the intestinal lumen, so water and electrolytes are expelled through the anus, causing watery diarrhea. Rotavirus enteritis is often prevalent in the late fall and early winter of each year, hence the name autumn diarrhea. Most of the children are infants and toddlers aged 6 months to 2 years, and the duration of the disease is usually about one week, with a good prognosis. Diarrhea is often preceded by 1-2 days of fever and vomiting, followed by watery stools, egg-like stools, ranging from 10 times a day to more than 10 times a day, and children with thirst, little urination and crying without tears. Autumn diarrhea is caused by a virus and the commonly used antibiotics are ineffective. The principles of treatment are prevention and correction of dehydration, continuation of diet, and rational use of medication.