Infectious diarrhea belongs to category C infectious diseases. Infectious diarrhea refers to a series of manifestations such as diarrhea caused mainly by microorganisms that infect the human body and enter the gastrointestinal tract of the body. The pathogens mainly include bacteria, viruses, protozoa, fungi, mainly according to the infection of specific microorganisms before these can be subdivided, if infected with the virus of cholera, belongs to the infectious diseases of category A. If a patient has frequent diarrhea and is diagnosed with typhoid fever, paratyphoid fever, amoebic dysentery, or dysentery bacillus infection at the hospital, these diseases belong to category B infectious diseases. Of course, there are other common diseases such as Escherichia coli, Salmonella and other infectious diseases, which belong to category C infectious diseases. Therefore, combined with the specific situation of the patient, the infectious diseases of category A and B should be isolated and treated in a timely manner to prevent transmission to others.