In the recent clinic, two cases of hand, foot and mouth disease (HFMD) were detected in succession in elementary school students, and they were reported and isolated, and both have recovered. Hand foot mouth disease (HFMD) is an infectious disease caused by enteroviruses, mostly in infants and children under 5 years old, causing fever and rashes and ulcers on the hands, feet and mouth, as well as myocarditis, pulmonary edema, aseptic meningoencephalitis and other complications in individual patients. There are more than 20 types of enteroviruses that cause HFMD, among which Coxsackievirus A16 (Cox A16) and Enterovirus 71 (EV 71) are the most common. HFMD is a global infectious disease, with epidemics reported in most parts of the world. it was first reported in New Zealand in 1957, coxsackievirus was isolated in 1958, and the name HFMD was proposed in 1959. In China, the disease was first seen in Shanghai in 1981, and an outbreak of HFMD caused by Cox A16 occurred in Tianjin in 1983. In recent years, there have been more reports of HFMD in China than before. (A) Source of infection The source of HFMD infection is patients and latently infected and asymptomatic carriers. During the epidemic, patients are the main source of infection. Patients excrete virus from the pharynx in 1 to 2 weeks after the onset of the disease, and from the feces in about 3 to 5 weeks, and the herpes fluid contains a large amount of virus, which spills out when it breaks. The herpes fluid contains a large amount of virus, and the virus is released when it breaks down. (b) Transmission is mainly through close contact between people. The virus in the throat secretions and saliva of patients can be transmitted by airborne droplets. It can be transmitted through daily contact with saliva, herpes fluid, fecal contaminated hands, towels, handkerchiefs, dental cups, toys, eating utensils, milk utensils, bedding, underwear, etc. It can also be transmitted through the mouth. Contact with water contaminated with the virus can also be transmitted orally and often causes epidemics. Cross-infection in outpatient clinics and poor disinfection of oral instruments can also cause transmission. (C) susceptible population People are generally susceptible to the enterovirus causing HFMD, and can gain immunity after being affected, and all age groups can be infected with the disease, but the ratio of recessive virus infection to dominant infection is 100:1, and most adults have acquired the corresponding antibodies through recessive infection, therefore, patients with HFMD are mainly preschool children, especially the highest incidence rate in the ≤3-year-old age group, and within 4 years of age accounts for 85% of the incidence ～The incidence of HFMD is particularly high in the ≤3 years age group, accounting for 85% of the cases within 4 years of age. According to foreign observations, the epidemic occurs every 2-3 years in the population, mainly during the birth of newborns during the non-epidemic period, and susceptible individuals gradually accumulate and reach a certain number, providing the prerequisites for a new epidemic. In Tianjin, China, after the epidemic in 1983, there was a continuous epidemic of disseminated cases, and the epidemic occurred again in 1986, and both times were caused by CoxAl6.