Viruses are very small and are highly contagious pathogenic agents which cause disease. Some viruses can survive and remain infectious in foods and the environment for long periods of time and can survive harsh conditions. Foodborne viruses account for an estimated 18% of the UK’s food poisoning incidents.
Norovirus also known as the winter vomiting disease and is the most common stomach bug in the UK and is highly infectious. The virus is easily transmitted from person-to-person so this accounts for a high proportion of cases. Outbreaks are common in semi-closed settings including carehomes, schools, nurseries, hotels and cruise ships. However norovirus infection can also occur through contact with contaminated environments; eating food which has been grown in or treated with contaminated water (e.g. shellfish or fresh produce); or by infected food handlers. The true contribution made by food to the rates of norovirus infection in Scotland is currently unknown, and FSA is funding a large programme of research to improve understanding in this area.
Symptoms of norovirus include vomiting, projectile vomiting, diarrhoea and fever. The virus usually causes mild symptoms and lasts for 1 to 2 days with most people making a full recovery. However the virus can be dangerous for the very young and the elderly.
The best way to prevent the spread of norovirus is through good hand hygiene. Wash hands thoroughly using soap and water and dry them thoroughly. Don’t rely on alcohol hand gels as they don’t kill norovirus. If you have norovirus it is important to stay off school or work (especially if you are a food handler) until the symptoms have stopped for 2 days, this will also help avoid the spread.
Hepatitis A virus
Hepatitis A virus is a liver infection that is spread by the faeces of an infected person. It causes a range of illness from mild symptoms including nausea, vomiting and fever through to hepatitis (liver inflammation, jaundice or icterus) and rarely liver failure. Hepatitis can be unpleasant but it is not usually serious and most people make a full recovery within a couple of months. Some people, particularly young children may not have any symptoms. Infection is followed by lifelong immunity.
You can get hepatitis A infection from:
- Eating food prepared by someone with the infection who hasn’t washed their hands properly
- Drinking contaminated water
- Eating raw or undercooked shellfish from contaminated water
- Close contact with someone who as hepatitis A
Symptoms of hepatitis A develop around 4 weeks after becoming infected but will usually pass within a couple of months. Symptoms can include:
- feeling tired and generally unwell
- joint and muscle pain
- a high temperature (fever)
- loss of appetite
- feeling or being sick
- pain in the upper-right part of your tummy
- yellowing of the skin and eyes (jaundice)
- dark urine and pale stools
- itchy skin
Someone with hepatitis A virus is most infectious from around 2 weeks before their symptoms appear until about a week after the symptoms first appear.
To avoid spread from person to person follow good hygiene measures such as washing your hands with soap and water regularly. Stay off school or work (especially if you are a food handler) until at least a week after the symptoms have started.
Hepatitis E Virus
Hepatitis E virus is also known as HEV and it causes hepatitis E infection. Both humans and animals can be infected by HEV. The virus is mainly associated with the consumption of raw or undercooked pork meat or offal, but also with wild boar meat, venison and shellfish.
For most people the symptoms of hepatitis E are mild so it does not require treatment and it clears up within 4 weeks. However in rare cases the disease can be serious, in some people, such as those who have a weakened immune system.
The risk of infection from hepatitis E virus is low if pork and pork products are thoroughly cooked. Therefore it is advised whole cuts of pork, pork products and offal should be thoroughly cooked until:
- The thickest part of the meat reaches at least 75°C with a food thermometer
- It is steaming hot all the way through
- The meat is no longer pink
- The juices run clear