Be Vigilant against Hepatitis A
An increase in the number of hepatitis A notification was observed in Hong Kong recently. Hepatitis A is an infection caused by hepatitis A virus (HAV) leading to inflammation of the liver cells. HAV can be transmitted by contaminated food, water or environmental surfaces, and through direct or indirect person-to-person contact. The consumption of raw or undercooked shellfish contaminated with the HAV is one of the common causes of infection, but other food items could also be implicated. In the latter scenario, a recent outbreak of hepatitis A in Australia was epidemiologically linked to consumption of a brand of frozen berries. (Investigation by the Centre for Food Safety found that the affected frozen berries have not been imported into Hong Kong.) Furthermore, cross contamination and poor personal hygiene of food handlers may contribute to the spread of HAV. Anyone who has not been previously infected with or is not immune to hepatitis A can contract the infection, and infection in children may be asymptomatic.
Codex and food safety regulatory authorities across the world have adopted the view that routine testing for viruses in food is of limited use because (i) the virus in contaminated food is usually present at such low levels that the pathogen cannot be detected by available analytical methods; (ii) the virus can be unevenly distributed and a test result may be negative but the food is still unsafe; and (iii) a positive test result can be due to the presence of genomic material from inactive or non-infectious virus in the food, but this does not mean the virus is active.
To prevent HAV infection, members of the public and the trade are advised to obtain food ingredients from reliable sources and maintain proper hygiene personally and during food preparation to prevent cross contamination. Thorough cooking, wherever applicable, remains a critical step to destroy HAV. People should be suspended from engaging in any food handling work when suffering or suspected to be suffering from an infectious disease or symptoms of illness such as flu, diarrhoea, vomiting, jaundice, fever, sore throat and abdominal pain. Foodborne hepatitis A infection can be prevented effectively by practising the “Five Keys to Food Safety”:
- Choose (Choose safe raw materials)
- Clean (Keep hands and utensils clean)
- Separate (Separate raw and cooked food)
- Cook (Cook thoroughly)
- Safe Temperature (Keep food at safe temperature)
Travellers can protect themselves by observing good personal hygiene and food hygiene. They can obtain further travel health advice at the webpage of Travel Health Service of the Department of Health: