Tokyo Food Safety Information Center » Good things to know » The microorganisms which cause food poisoning » Viral hepatitis A
Viral hepatitis A
Hepatitis type A is an infectious disease caused by the hepatitis A virus. This virus is strong against acids and tolerant to alcohol. Sufficient heating (85℃ for one minute or more) is required for inactivation. The virus once ingested through the mouth into the body cannot be inactivated and is discharged through feces.
Which foods can cause viral hepatitis A infection?
Water and food contaminated with norovirus, and particularly bivalves such as oysters have been widely reported to have caused norovirus. Norovirus cannot multiply inside shellfish. Instead, it is believed that norovirus accumulates inside bivalves when their environment becomes contaminated with the virus.
Secondary infection may also be caused by contact with the stool or vomit of infected persons.
When infected persons prepare food after using the bathroom and fail to wash their hands sufficiently, the food can become contaminated with norovirus. When this food is eaten in turn, infection can occur.
What are the symptoms of viral hepatitis A infection?
The incubation period is two to seven weeks (four weeks on average). The symptoms include: diarrhea, fever (initially, pyrexia (raised body temperature) of 38℃ or higher that continues for three to four days), malaise (languor), nausea, vomiting, jaundice, and hepatomegaly (enlarged liver). Most infants indicate no symptoms, or slight symptoms even if infected. However, attention should be paid if middle aged and elderly persons who have low immunity are infected and develop the symptoms, as their conditions will be likely to become severe. In most cases, liver function is recovered in a month or two; and if once infected, the person will never be infected again.
What are the key points to preventing viral hepatitis A infection?
- Wash and disinfect your hands sufficiently after defecation or urination, before cooking, and before having meals.
- Do not drink raw water in the countries and regions where type-A hepatitis viruses commonly exist. In addition, pay attention to ice and popsicle products made from raw water.
- Eat well heated foods.