Schools are one of the most densely populated places: limited classroom space, many people, narrow space, poor ventilation, dirty air, once encountered with infectious bacteria, viruses, parasites, the spread of rapid, easy to form an epidemic of infectious diseases and outbreaks of well. It is not uncommon for a student to be infected with a disease, a dormitory, a class, a grade or even the whole school. It is necessary to strengthen the prevention of common infectious diseases among school-age children and adolescents, such as hand, foot and mouth disease, scarlet fever, chicken pox, measles, mumps, etc., in the face of various stages of students returning to campus and children regrouping at the turn of summer and autumn, when various infectious diseases are breeding. 1, head lice The classroom is a breeding ground for a variety of microorganisms that cause disease in young children, such as head lice is one of them, commonly found among preschoolers in kindergarten, children in elementary school, and family members raising children. Using the picture as a guide, check if any affected children fit the above-mentioned manifestations of infection after they return to the classroom for timely and symptomatic treatment. Head lice are a parasite that is almost exclusively parasitic on the human head, causing itching and less frequently infesting the eyebrows and eyelashes. The lice are most often transmitted through direct contact with the hair of an infected person and less often through contact with the patient’s clothing (e.g., hats, scarves, coats) or other personal items (e.g., combs, toothbrushes, towels). Whether or not transmission occurs has little to do with personal hygiene and cleanliness within the home or school. Diagnosis of head lice should be confirmed by trained medical personnel, and patients often mistake lint fibers for lice. The best way to confirm the diagnosis is to identify the eggs, which often grow on the hair shaft less than 5 mm from the scalp. The empty hair sheath (a white tubular substance surrounding the outside of the hair) can be seen further down the scalp and does not need to be removed with a fine-toothed grate. Tinea capitis is a pruritic fungal infection of the scalp that can occur at any age and is most common in children. Typically affected areas show a patchy, round, scaly red or inflammatory appearance. Patients present with low-grade fever, swollen lymph nodes in the neck, and abscesses (tinea cruris). Tinea capitis infection is contagious and is easily transmitted through direct contact with the infected person’s body parts, touching personal items used by the infected person (such as combs, hats, clothing), and pets (especially cats). Diagnosis is often made clinically, but the diagnosis is confirmed by Wood’s lamp examination and/or culture. Oral medications (e.g., ashwagandha, terbinafine, itraconazole) are best used to treat tinea capitis because topical medications tend to rub off quickly; tinea capitis tends to recur after treatment; and family contacts and pets need to be evaluated and treated during the course of treatment. The disease is less commonly seen after puberty. Hand, foot and mouth disease Hand, foot and mouth disease is an acute viral infectious disease caused by enteroviruses of the genus Coxsackievirus A 16, followed by type 5 and type 10; in addition, there is enterovirus 71 also associated with outbreaks of hand, foot and mouth disease. HFMD is usually seen in young children younger than 5 years of age, but can also occur in adults. Symptoms/signs include rash, intraoral (herpes pharyngitis) and perioral herpes or ulcers, and fever. Transmission is through direct person-to-person contact, airborne transmission, or contact with infected objects/surfaces. Shedding of viral particles can be found in the saliva, sputum, nasal discharge, herpes fluid and stool of infected individuals. Diagnosis can be made by the clinical presentation of the patient and, if necessary, by throat swab or stool culture. There is no specific treatment available. Symptomatic supportive treatment includes over-the-counter pain relievers/fever reducers (do not give aspirin to children), mouthwash, or sprays. 4. Scarlet fever is a disease caused by infection with group A beta-hemolytic streptococcus (GABHS), which releases three erythrogenic exotoxins. The usual age of onset is 5 to 12 years. The first rash appears on the neck and chest and has a “sandpaper-like” appearance, then the rash spreads throughout the body and lasts a week or more; the texture of the rash is more diagnostic than the appearance. Other signs/symptoms include fever, pharyngitis, chills, vomiting, and abdominal pain; typical signs include “strawberry tongue,” which presents with a white tongue that is peeling, bright red, and a prominent red and swollen tongue papilla that resembles a red and white strawberry-like appearance; palm desquamation is often seen, which occurs during the recovery period after infection and acute rash and is self-limiting. Throat swab cultures are often negative for GABHS, so the diagnosis is often made by the patient’s clinical presentation and treated with antibiotics. The key point in treating scarlet fever is that if it is not treated thoroughly, it will progress to rheumatic fever in 3% of patients. 5. Bacterial conjunctivitis is a common infectious eye disease caused by bacterial infection in children. Characteristic signs include scleral congestion and redness of the surrounding skin with mucus or pus effusion. Although antibiotic treatment can reduce complications as well as provide rapid relief, most cases are self-limiting. Bacterial conjunctivitis in children is most often caused by Haemophilus influenzae or Streptococcus pneumoniae; of these, Haemophilus influenzae conjunctivitis predisposes to transmission of infection in schools and families, and the disease is associated with concurrent upper respiratory infections and otitis media. The disease is usually diagnosed on the basis of clinical manifestations. In most cases, bacterial conjunctivitis can be treated with empirical antibiotics administered topically.