Food poisoning is rarely serious but there are some viruses that can result in an illness so severe some people end up in hospital needing treatment. Symptoms of food poisoning usually develop within a few days or hours of eating the food that caused the infection.
It is important to know the symptoms of food poisoning and when to seek help. It comes after Public Health Wales confirmed on Monday it was investigating a potential outbreak of the shigella virus in the Abergavenny area of Wales.
It said it had been alerted to an increase in cases of "gastrointestinal" illness in the area, which might have been caused by shigella infection. WalesOnline is aware of several people who have experienced sickness and diarrhoea after eating from a takeaway restaurant in Abergavenny on February 12. You can get more health news and other story updates straight to your inbox by subscribing to our newsletters here.
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What are the symptoms of food poisoning?
According to the NHS, symptoms of food poisoning include:
- feeling sick (nausea)
- diarrhoea
- being sick (vomiting)
- stomach cramps
- a high temperature of 38C or above
- feeling generally unwell – such as feeling tired or having aches and chills
How to treat food poisoning
Food poisoning is usually treatable at home. The symptoms usually pass within a week and the most important thing is to have lots of fluids to avoid dehydration.
The NHS advises people to stay off school or work until you have not been sick or had diarrhoea for at least two days.
When to see your GP
You should contact your GP if your symptoms of food poisoning are severe and you can't keep fluids down. You should also contact them if:
- your symptoms don't start to improve after a few days
- you have severe dehydration and are experiencing confusion, a rapid heartbeat, sunken eyes and passing little or no urine
- you're pregnant
- you're over 60
- your baby or young child has suspected food poisoning
- you have a long-term underlying condition, such as inflammatory bowel disease (IBD), heart valve disease, diabetes or kidney disease
- you have a weak immune system – for example, because of medication, cancer treatment or HIV
What causes food poisoning
Food poisoning is caused by eating food that is contaminated with germs. The NHS says this can happen if food:
- is not cooked or reheated thoroughly
- is not stored correctly – for example, it's not been frozen or chilled
- is left out for too long
- is handled by someone who's ill or has not washed their hands
- is eaten after its "use by" date
What are the different types of infection and viruses that can cause the illness?
Campylobacter bacteria
This is the most common cause of food poisoning in the UK. The bacteria is usually found on raw or uncooked meat, unpasteurised milk and untreated water. Symptoms usually appear within two and five days and last less than a week.
Shigella
Shigella can contaminate any food that has been washed in contaminated water. Symptoms typically develop within seven days and can last for a week.
Salmonella bacteria
Salmonella is often found in raw or uncooked meat, raw eggs, milk and other dairy products. Symptoms usually appear within 12 to 72 hours and last around four to seven days.
E. coli bacteria
Escherichia coli is a bacteria found in the digestive systems of many animals including humans. Most strains are harmless but some cause serious illness. Most cases of e.coli food poisoning are the result of eating undercooked beef or drinking unpasteurised milk. E.coli symptoms can appear between one and eight days after consumption and can last for a few days or weeks.
Listeria
Listeria can be found on "ready-to-eat" foods including pre-packed sandwiches, cooked, sliced meats and pate and soft cheeses such as brie and camembert. All of these foods should be eaten by their use-by dates. It is particularly important for pregnant women to follow this advice as listeria in pregnancy can cause pregnancy and birth complications. The incubation period for listeria can vary drastically. Symptoms may appear after a few days or several weeks. Symptoms usually pass within three days.
Viruses (norovirus)
Norovirus is the most common cause of diarrhoea and vomiting. It is easily spread from person to person and contaminated food and water. Symptoms usually appear within 24 to 46 hours and pass within a couple of days. Parents are being told to look out for signs of norovirus in their children as cases of the winter vomiting bug can soar in schools and nurseries. Public Health Wales said the virus was extremely infectious and cases had been rising.
Parasites
Food poisoning caused by parasites in the UK is rare and is more commonly found in the developing world. The symptoms of food poisoning caused by a parasite usually develop within 10 days of eating contaminated food although it can sometimes be weeks before you feel unwell. If left untreated, the symptoms can last a long time – sometimes several weeks or even a few months.
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