What Are the Main Transmission Routes of Hepatitis A?

Hepatitis A is a contagious liver disease caused by the hepatitis A virus (HAV), leading to inflammation of the liver. The primary mode of transmission is through the fecal-oral route, meaning the virus spreads when an uninfected person consumes food or water contaminated with the feces of an infected individual.

Infected individuals, including those who are asymptomatic, serve as the main sources of transmission. The virus is excreted in the feces and can easily contaminate water sources, food items, vegetables, and kitchen utensils. When these essentials become contaminated, they can lead to widespread outbreaks of the disease.

A notable example of a foodborne hepatitis A outbreak occurred in Shanghai in 1988. Within four months, approximately 310,000 cases were reported due to the consumption of undercooked clams contaminated with fecal matter. This large-scale outbreak highlights the potential risk of consuming contaminated shellfish or untreated water.

In everyday settings, hepatitis A transmission typically occurs in isolated or sporadic cases. The virus can also appear in the bloodstream of an infected person, usually 14 to 21 days before the onset of jaundice. During this period, the individual's blood remains infectious. Although there have been rare reports of transmission through blood transfusions, this is considered an uncommon route.

People who have not been vaccinated against hepatitis A are generally susceptible to the virus. However, those who have recovered from a previous infection or have been successfully immunized can develop long-lasting immunity, protecting them from future infections. Vaccination remains one of the most effective ways to prevent hepatitis A transmission.