Hand, foot and mouth disease (HFMD) is an infectious disease caused by enteroviruses, mostly in infants and young children, which can cause herpes on the hands, feet and mouth, and individual patients can cause complications such as myocarditis, pulmonary edema and aseptic meningoencephalitis. There are more than 20 enteroviruses (types) that cause HFMD. Coxsackievirus types 16, 4, 5, 9, and 10 of group A, types 2 and 5 of group B, and enterovirus type 71 are the more common pathogens of HFMD, with coxsackievirus type A16 (Cox A16) and enterovirus type 71 (EV71) being the most common. The incubation period of the disease is 2 to 7 days, and the source of infection includes patients and latent infections. During epidemics, patients are the main source of infection. Patients can excrete virus from the pharynx during the acute phase of the disease; herpes fluid contains a large amount of virus, which is spilled when it breaks; and the virus can still be excreted in the stool several weeks after the disease. The disease is transmitted in various ways, mainly through close contact with people. The virus can be spread through indirect contact with hands, towels, handkerchiefs, dental cups, toys, eating utensils, milk utensils, bedding, underwear, etc. contaminated with saliva, herpes fluid, feces, etc.; the virus in the patient’s throat secretions and saliva can be spread through droplets; if contacted with water contaminated with virus, it can also be infected through water; cross-infection in outpatient clinics and unqualified disinfection of oral instruments are also one of the causes of transmission. The population is generally susceptible to the enterovirus that causes HFMD, and immunity can be acquired after infection. Because of the lack of cross-protection of antibodies after infection with different pathotypes, the population can be repeatedly infected. Adults have mostly acquired the appropriate antibodies through occult infection; therefore, patients with HFMD are mainly preschool children, with the highest incidence especially in the &;le; 3-year-old age group. According to foreign literature, epidemics can occur in the population every 2 to 3 years. HFMD is widely distributed and has no obvious regional distribution; it can occur in all seasons, with a high incidence in summer and autumn. The disease often occurs sporadically after an epidemic; during the epidemic, kindergartens and nurseries are prone to collective infections, and families can also experience clusters of illness. The disease is highly contagious, the transmission route is complex, and can cause a large scale epidemic in a short period of time. 4, clinical manifestations 4.1 typical cases: incubation period is generally 2-7 days, no obvious prodromal symptoms, most patients suddenly onset. About half of the patients have fever 1-2 days before onset or at the same time of onset, mostly around 38℃, lasting 2-3 days, a few patients more than 3-4 days. Fever is almost always present with central nervous system comorbidities and lasts for a long time. Some patients initially have mild upper sensory symptoms, such as cough, runny nose, nausea, vomiting, etc. Due to painful oral mucosal ulcers, children have salivation and refusal to eat. Oral mucosal rash appears early, mainly on the tongue and cheeks, and often on the side of the lips and teeth. A maculopapular or herpetic rash appears on the distal parts of the hands and feet. The maculopapular rash turns from red to dark in about 5 days and then fades; the herpes is round or oval with flattened projections and cloudy fluid inside, with the same length and diameter as the skin lines, such as the size of a soybean. The papules and herpes on the distal parts of the hands and feet are usually painless and itchy, and do not leave traces after healing. In the same patient hand, foot and mouth lesions may not all appear. 4.2 Atypical, disseminated cases: The rash is only manifested on one part of the patient’s body, and the maculopapular or herpetic rash is sparse and atypical, often difficult to distinguish from rash febrile disease, and pathogenic and serologic tests must be performed. 4.3 Comorbidities: Some may be combined with myocarditis, encephalitis, meningitis, chorioretinitis, pulmonary edema, etc., but aseptic encephalitis and myocarditis are the most common. 5. Laboratory tests 5.1 The total cell count in blood tests is generally normal or high, with higher lymphocytes and lower neutrophils in the classification. 5.2 In the presence of central nervous system complications, the cerebrospinal fluid cell count may increase and protein may be elevated. 5.3 Associated viruses are isolated or detected from stool and throat gargle after the onset of disease. 5.4 Associated viruses are isolated or detected from cerebrospinal fluid or herpes fluid. 5.5 Detection of IgM antibodies to the associated virus from early serum. 5.6 There is a 4-fold increase in serum neutralizing antibodies in the recovery phase compared to the acute phase.