Hepatitis A (Hep A) is a liver infection caused by the Hepatitis A virus (HAV), which leads to inflammation of the liver. While the infection often causes mild symptoms or none at all, especially in young children, it can result in a severe illness lasting several weeks to months in adults. The virus spreads primarily through direct contact with an infected person, but contamination of food and water is a significant route for widespread outbreaks. The virus is highly resilient and survives standard food production processes that eliminate bacteria.
How Hepatitis A Enters the Food Supply
Food contamination typically begins with the virus being shed in the feces of an infected person. Contamination frequently occurs when an infected food handler does not practice proper hand hygiene after using the restroom before preparing food for others. The individual may not even be aware they are sick, since the virus is most contagious during the two weeks before symptoms, such as jaundice, begin to appear.
The Hepatitis A virus can survive for several hours on hands and for days on environmental surfaces. If a food handler touches a ready-to-eat item without washing their hands, the virus transfers directly to the food, which is then consumed without further cooking. Water contamination also serves as a major vector, especially in areas with poor sanitation and sewage treatment. Contaminated water can be used to irrigate crops or clean produce during processing, introducing the virus to the food supply.
The second major pathway of contamination involves water sources used for harvesting certain foods, particularly shellfish. Shellfish are filter feeders; if the water source is polluted with sewage or human waste containing the virus, they concentrate the viral particles inside their tissue. This concentration effect means that even a small amount of contamination in the water can lead to a high infectious dose in the final product.
High-Risk Foods Commonly Associated with Transmission
The ability of the Hepatitis A virus to survive outside a host means that several food categories pose a risk, especially those consumed raw or minimally cooked. Raw or undercooked shellfish, such as oysters and clams, are among the most common foods linked to large-scale outbreaks. Traditional steaming or light cooking methods may not be sufficient to inactivate the HAV.
Fresh produce represents another high-risk category, particularly fruits and vegetables eaten without peeling or cooking. Contamination can occur in the field through infected irrigation water or during the washing and packing stages. Berries, including frozen strawberries and blueberries, have been implicated in outbreaks because they are often consumed raw and their porous surfaces make them difficult to clean thoroughly.
Leafy greens, like lettuce and spinach, present a vulnerability because they can be contaminated in the field and are frequently consumed raw in salads. Green onions were famously the source of a large outbreak when they were contaminated before being used in a restaurant setting. Additionally, any ready-to-eat food that requires extensive handling after preparation becomes a potential transmission vehicle. Items such as deli sandwiches, prepared salads, and baked goods are vulnerable to contamination by an infected food worker because no subsequent cooking step exists to destroy the virus.
Essential Steps for Prevention and Protection
The most effective way to prevent Hepatitis A infection is through vaccination, which provides long-term protection against the virus. The Hepatitis A vaccine is recommended for all children and is a primary preventative measure for travelers to areas with high infection rates or for individuals with other risk factors. For an unvaccinated person exposed to the virus through contaminated food, a dose of the vaccine or immune globulin given within two weeks can prevent or lessen the severity of the illness.
Consumer actions centered on hygiene and proper food handling significantly reduce the risk of infection. Thorough handwashing with soap and warm water for at least twenty seconds is necessary, particularly after using the restroom and before preparing or eating food. It is also important to source shellfish from reputable suppliers to ensure the product was harvested from approved waters.
When preparing food at home, washing all fresh produce thoroughly under running water helps remove surface contaminants. Shellfish must be cooked completely, as the virus is relatively resistant to heat and requires temperatures of 185°F (85°C) or higher for at least one minute for inactivation. Travelers to regions where sanitation is a concern should consider drinking bottled water and avoiding foods that cannot be peeled or that may have been washed with untreated water.