Seasonal hepatitis, mainly hepatitis A and E, is disseminated throughout the year with significant winter and spring peaks; non-seasonal hepatitis, mainly hepatitis B, C, and D, is disseminated throughout the year but without significant seasonal peaks. It should be emphasized that while sporadic hepatitis A and E have significant winter and spring peaks, epidemic hepatitis A and E often occur during the tropical rainy season and subtropical/ temperate summer and fall. Sporadic means that the absolute number of patients is higher than the average over the years and that there is no correlation between the incidence of different patients; epidemic means that the absolute number of patients is significantly higher than the average over the years and that there is a correlation between the incidence of different patients. The basic mode of transmission of hepatitis A and E is fecal-oral transmission. Hepatitis A virus infects only humans and a limited number of primates; however, hepatitis E virus has a much broader host range, infecting not only humans and primates but also domestic animals, poultry, and livestock, such as pigs, chickens, and horses. The virus replicates in hepatocytes, drains into the bile ducts via the capillary bile ducts and then into the intestine, where it is excreted in the feces of infected individuals. Among the five known hepatitis viruses, hepatitis A virus has the strongest environmental resistance and survives for a long time in acidic, alkaline and low temperature environments, but is sensitive to ultraviolet light, while hepatitis E virus has relatively weak environmental resistance and dies rapidly after leaving the weak alkaline environment of the intestine, but can survive for a long time by freezing. Therefore, the main modes of transmission of sporadic hepatitis A include contact transmission and food transmission; while the main modes of transmission of sporadic hepatitis E are limited to food transmission. The primary mode of transmission for both epidemic hepatitis A and E is waterborne. Transmission through fecally contaminated hands and objects is called direct or indirect contact transmission, respectively; transmission through fecally contaminated food is called food transmission; and transmission through fecally contaminated water is called waterborne transmission. The main populations of human hepatitis A and E are adolescents and young adults, respectively, while hepatitis A is rare in the elderly but hepatitis E is common. The incubation period (time from infection to onset) for hepatitis A and E is 3 to 8 weeks and 2 to 6 weeks, respectively. The initial manifestations are fever, malaise and loss of appetite, and in severe cases, nausea and vomiting; the frequency of fever in hepatitis A and E is 80% and 40%, respectively; the temperature rarely exceeds 39°C, and the duration is mostly 1 to 2 days, a few 3 to 5 days, and individually up to 1 week. The duration of malaise and decreased appetite is usually 5 to 7 days and 7 to 10 days, respectively. Some patients develop deepening of urine color with a red tea color about 1 week after the onset of the disease, along with yellowing of the skin and sclera. Those who appear and those who do not appear yellow staining of skin and sclera are called jaundiced and non-jaundiced hepatitis respectively; if malaise and loss of appetite progressively worsen for more than 3 weeks and yellow staining of skin and sclera progressively worsen for more than 2 weeks, the possibility of severe hepatitis should be considered. Further progression of severe hepatitis can result in critical hepatitis, which is the main type of disease leading to death in hepatitis patients. The natural course of hepatitis A and E is 2 to 4 weeks and 4 to 8 weeks, respectively; the morbidity and mortality rates are 0.1% to 0.3% and 1% to 3%, respectively. Once diagnosed with seasonal hepatitis, all require hospitalization. First, the need for isolation, hepatitis A and E are legal infectious diseases, the infectious period is 3-6 weeks after the onset of the disease, isolation treatment can help prevent the spread of disease and protect friends and relatives; Second, the need for symptomatic and supportive treatment, symptomatic treatment can reduce pain, supportive treatment can help the disease recovery; Third, the need to observe the disease, patients with a tendency to heavy hepatitis, early detection and early treatment can stop disease progression and reduce the risk of death. Seasonal hepatitis usually does not require antiviral therapy. There are two specific preventive measures for seasonal infections: passive immunization, i.e. immunoglobulin, to reduce morbidity if there is contact with an infected person during the peak season; and active immunization, i.e. vaccination to prevent infection when there is no contact with an infected person before the peak season. Immunoglobulin vaccination is preventive for hepatitis A, but not for hepatitis E. There is an effective hepatitis A vaccine available, but there is no vaccine for hepatitis E that has been shown to be effective. Thus, hepatitis A can be prevented by active and passive immunization, but there are no reliable active and passive immunization methods for hepatitis E. Non-specific prophylactic measures to prevent seasonal hepatitis, especially hepatitis E. Developing good hygiene habits, especially frequent hand washing and eating cooked food, remain the most basic preventive measures.