What are the transmission routes of hepatitis A?

Sep 19, 2025 Source: Cainiu Health

Dr. Gao Jun

Introduction

In general, hepatitis A is caused by the hepatitis A virus and can be transmitted through food, drinking water, direct contact, medical procedures, and vertical transmission from mother to child. Maintaining good dietary hygiene, frequent handwashing, and receiving the hepatitis A vaccine can effectively reduce the risk of infection. If symptoms such as fatigue, loss of appetite, or darkened urine occur, prompt medical attention is recommended.

Generally, hepatitis A is caused by the hepatitis A virus, and its transmission routes include foodborne transmission, waterborne transmission, contact transmission, iatrogenic transmission, and mother-to-child vertical transmission. The details are as follows:

1. Foodborne transmission

This is one of the common routes, especially associated with raw or undercooked foods. Hepatitis A virus can accumulate in shellfish; if the waters where shellfish grow are contaminated by feces from infected individuals, consuming undercooked contaminated shellfish allows the virus to enter the liver via the digestive tract.

2. Waterborne transmission

This often occurs when drinking water sources are contaminated with hepatitis A virus and not properly disinfected. In areas with poor sanitation, rainwater runoff may carry fecal matter into water supplies, or inadequate treatment processes in municipal water systems may fail to eliminate the virus. Drinking such untreated contaminated water can easily lead to outbreaks of hepatitis A.

3. Contact transmission

This commonly occurs in settings involving close personal contact, such as households, schools, and kindergartens. Feces of infected individuals contain large amounts of hepatitis A virus. If proper hand hygiene is not observed after using the toilet, the virus can be transferred to hands and subsequently contaminate objects like utensils, towels, door handles, and toys. Susceptible individuals may become infected when they touch these contaminated surfaces and then touch their mouth.

4. Iatrogenic transmission

This route has a low incidence but still requires vigilance. If medical instruments are contaminated with hepatitis A virus and are not thoroughly cleaned, disinfected, or sterilized before reuse on other patients, cross-infection may occur. Additionally, transmission through blood transfusion is extremely rare because the hepatitis A virus primarily resides in the gastrointestinal tract and is present in very low levels in the bloodstream.

5. Mother-to-child vertical transmission

This mode of transmission is uncommon and only occurs when a pregnant woman experiences acute hepatitis A infection around the time of delivery. The virus may be transmitted to the fetus through maternal blood, amniotic fluid, or birth canal secretions. However, most newborns exhibit asymptomatic infections and do not develop chronic hepatitis. With timely symptomatic management, full recovery is expected.

Maintaining good dietary hygiene, frequent handwashing, and receiving the hepatitis A vaccine can effectively reduce the risk of infection. If symptoms such as fatigue, loss of appetite, or darkened urine appear, prompt medical attention is recommended.

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What is liver disease?

Liver disease refers to pathological changes occurring in the liver, including various types such as hepatitis B, hepatitis A, hepatitis C, cirrhosis, fatty liver disease, liver cancer, alcoholic liver disease, and others. It is a common and highly harmful disease. In daily life, to prevent the occurrence of liver disease, timely vaccination against hepatitis B should be administered to reduce the risk of hepatitis B virus infection.

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How many days after being infected by a hepatitis A patient will symptoms appear?

Under normal circumstances, patients with hepatitis A (HAV) are infected with the hepatitis A virus. After being infected with the hepatitis A virus from a patient with hepatitis A, symptoms may appear within 2 to 6 weeks, depending on the individual's incubation period and the activity of the virus. In daily life, close contact with hepatitis A patients should be avoided as much as possible, including sharing eating utensils, drinking glasses, kissing, and similar activities.

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Is hepatitis A vaccinated with a live attenuated or inactivated vaccine?

Under normal circumstances, "Jia Gan" refers to hepatitis A, "Jian Du" refers to attenuated vaccines, and "Mie Huo" refers to inactivated vaccines. Hepatitis A vaccines include both attenuated and inactivated vaccines, and both types can be used for the prevention of hepatitis A. The choice between the two can be made according to individual circumstances and medical advice. In daily life, it is important to ensure the safety of drinking water, and it is recommended to drink water that has been boiled or purified.