How Does Hepatitis A Spread Through Food?
In a developed country such as the United States, outbreaks of Hepatitis A (HAV) from contaminated food are not common but are still possible and have occurred in the past. Some outbreaks have been linked to thousands of cases. It can be difficult, however, to pinpoint the source of infection because of the late onset of symptoms especially when the victims are geographically scattered. A food product can become contaminated at any step during the process of harvesting, distribution, preparation, etc… When the problem occurs at one of the early stages, say during production, this can lead to a wide-spread outbreak, such as recent outbreaks of HAV linked to imported pomegranates or HAV linked to imported strawberries.
However, most recorded HAV outbreaks in the United States have occurred at the point of sale when food is handled and served in a restaurant. While most food handlers with HAV do not transmit the virus because they practice proper personal hygiene, all an infected person has to do to spread the virus is touch food after failing to wash their hands. These “establishment” HAV outbreaks are usually in a single geographic location tied to a particular restaurant, like the relatively recent Burger King or Famous Anthony’s outbreaks.
Infection with HAV starts by ingesting food or water that has been contaminated with the virus. The virus odes ot “grow” or multiply outside the digestive tract, but can lie dormant for weeks or longer. Once ingested, however, it begins to replicate quickly. Only a very small amount of the virus is needed to make a person sick. The victim often becomes sick 15 to 50 days after ingestion of HAV. F a person receives a HAV vaccine after exposure but before symptoms, they may be able to prevent illness.
There are certain foods that are more likely to transmit the virus than others. Many past outbreaks have involved raw fruits and vegetables such as the HAV green onions outbreak, pomegranates HAV outbreak, and HAV strawberries outbreak. The physical traits of these foods require a great deal of handling, making them more likely to become contaminated during harvesting and packing. These products are not cooked, and washing can be difficult. They are often contaminated at the farm or factory well before even reaching the restaurant or grocery store. HAV outbreaks has also been linked to shellfish, which can also become easily contaminated if proper food manufacturing standards are not followed. Transmission to shellfish has also been known to occur from harvesting the shellfish near areas with sewage contaminated waters.
The best way to prevent the transmission of HAV in food is following proper hygienic practices. Proper and frequent hand washing and avoiding as much bare hand contact with food as possible helps to reduce the spread from an infected person. Cooking food to a temperature of 185 also inactivates the virus. Freezing does not kill HAV.
Note: HAV is the only vaccine preventable food borne illness in the United States and receiving the vaccine protects against the spread of the virus. Some areas across the country have begun to require proof of HAV vaccinations for food handlers.
