Viruses are different to bacteria because they’re not living organisms, they are DNA in a protective shell. This means they don’t multiply in food or water, they just use them as a vehicle to get into your body. You only need a small dose to make you ill. It’s after entering the body that a virus multiplies in your cells.
Viruses are present in vomit, so are easily spread through the air, from landing on surfaces and from person-to-person i.e. shaking hands.
There are two main ones in terms of food safety; norovirus and hepatitis A.
Both cause symptoms including fever, nausea, vomiting, diarrhoea and stomach pain.
Both are found in contaminated water, raw shellfish, vegetables, salads etc.
Norovirus
It is the most common type of gastroenteritis in the U.K. It’s often called the winter vomiting bug.
It’s very contagious and can spread from person to person, so it’s common on cruise ships and other places where people may be in close contact such as schools, nurseries, nursing homes, prisons, hospitals etc.
Food handlers can contaminate food with norovirus particularly foods which are handled a lot such as desserts, cooked meats, salad items and sandwiches. Also, shellfish that have been harvested from waters contaminated with sewage can be a source of norovirus.
The onset time is around 1-2 days.
The duration is usually 1-3 days.
Hepatitis A
It’s uncommon in the U.K. due to us having clean water systems, but it’s very common in developing countries, particularly where there are poorer hygiene standards. It can be contracted when people travel to these countries.
Besides the common symptoms of stomach cramps, nausea, vomiting and diarrhoea, it can also cause jaundice.
The onset time is 20-50 days.
The duration is from one week to many months.
The controls for norovirus and hepatitis A include:
- Using reputable suppliers (i.e. for sourcing shellfish).
- Excluding infected food handlers and making sure they don’t return to working with food until it is safe to do so.
- Using a potable water supply and boiling non-potable water.
- Thoroughly washing fruit, vegetables and salad items that aren’t going to be cooked.
- Ensuring high standards of personal hygiene including thorough and regular hand washing.
- Thoroughly cleaning and disinfecting surfaces and equipment.
