Food poisoning
Food poisoning is caused by eating contaminated food. Bacteria, viruses or toxins which are naturally present in meat, fish or plants are usually the cause of food poisoning. Metals and chemicals in food can also be the cause.
The incubation period (time taken from eating the food to feeling unwell) varies with each type of bacteria and, in some cases, may occur up to 15 days later. This means that the last meal you ate before getting ill may not be the cause of your symptoms.
Many viruses have similar symptoms to food poisoning but may not be food related.
People with food poisoning may have a range of symptoms but the most common are abdominal pains, diarrhoea and vomiting.
Food poisoning or food borne illness can spread quickly. Everyone in the family could have eaten the same food and the bacteria may be passed on by close family contact.
Viruses cause illness similar to food poisoning and also spread very quickly.
If you suspect you have food poisoning it is recommended that you visit your doctor as soon as possible, who might ask you to provide a faecal sample for examination.
Samples are useful in that they might be able to show which food-borne illness you are suffering from, or could rule out a food-poisoning organism. Viruses can also be detected.
Consult your doctor immediately if the person affected:
- is a baby
- is elderly
- has an existing illness or condition
- has symptoms that are prolonged or severe, such as blood in your diarrhoea.
You will need to go to your doctor and give a faecal specimen. This will be tested and then you will be given the results or diagnosis.
If you have been diagnosed as having food poisoning by your doctor, they will tell us.
We will then contact you, depending on the type of food poisoning you are suffering, either by telephone or sending a questionnaire through the post.
A food history will be collected, usually covering the five days before your symptoms started.
It is a good idea to try to do this whenever you think you may be suffering from food poisoning, as it can be very hard to remember what you have previously eaten just a few days later.
If you or a member of your family is suffering from the symptoms of food poisoning, follow this advice to try and prevent the spread of the illness.
- Wash your hands after contact with the sick person and before handling food.
- The sick person should avoid preparing food altogether.
- Do not use the same towel or face cloth as someone who is suffering with food borne illness.
- Clear up soiling accidents straightaway, wash with hot soapy water and disinfect with a disinfectant or bleach.
- Disinfect door and toilet handles, taps and the toilet seat after use and disinfect the toilet bowl frequently.
- Drink plenty of fluids while you are ill to prevent dehydration.
If you are suffering from food poisoning symptoms (listed above) and you handle food as part of your job, you must inform you employer.
If you have diarrhoea and or vomiting you should not enter a food handling area until you have had no symptoms for 48 hours.
If you work in the caring industry such as health professional, health care assistant, nursery worker or care for any vulnerable people you must inform you employer. You must stay away from work until you have had no symptoms for 48 hours.
If you have any queries relating to food poisoning or infectious disease, you can contact us.
Common causes of food poisoning
Two species of campylobacter, C. jejuni and C. coli, cause most infections. The bacteria live in the gastrointestinal tract of mammals including livestock and pets such as dogs and cats.
People often get C. jejuni and C. coli from:
- raw or undercooked meat, especially poultry
- unpasteurised milk
- untreated water
For most infections, it’s difficult to trace it back to the exact source. Other causes include contact with pets that have diarrhoea or contact with livestock. Bacteria can also spread through poor hygiene in food preparation, for example, if you don’t wash your hands, you can spread bacteria from chicken to salads.
The incubation period is usually 2 to 5 days. But it can be as short as 1 day and up to 11 days.
There are more than 2,500 strains of salmonella bacteria. These live in the guts of domestic and wild animals including, chicken, cattle, pigs, hedgehogs, snakes and lizards.
Salmonella causes food poisoning. Foods such as eggs, chicken, pork and dairy produce can carry salmonellas. Fruit and vegetables can also become contaminated if they have been in contact with livestock, manure or untreated water. People preparing food should make sure that they wash their hands and clean kitchen equipment thoroughly to prevent the spread of salmonellas from meat to other foods in the kitchen. People can also become infected from contact with individuals with diarrhoea or from unwell animals.
Symptoms of diarrhoea, stomach cramps, nausea, vomiting and fever usually develop between 12 and 72 hours after becoming infected. Illness usually lasts from 4 to 7 days. People with severe or prolonged symptoms should consult a doctor.
Shiga toxin-producing Escherichia coli (STEC) are a group of bacteria that cause infectious gastroenteritis. Historically the most frequently reported STEC strain to cause illness in England was STEC O157; however, in recent years reports of non-O157 STEC infections have increased. In England around 1,500 cases of STEC (O157 and non-O157) are reported each year.
Symptoms can range from mild gastroenteritis through to severe bloody diarrhoea, and typically appear 3 to 4 days after consuming contaminated food or water.
Sometimes people with STEC infection can develop haemolytic uraemic syndrome (HUS), a serious condition affecting the blood, kidneys, and the central nervous system, which can also result in death.
The main reservoir for STEC is cattle and other ruminants. Transmission to humans occurs through:
- consumption of contaminated food or water
- contact with animals or their faeces
- contact with a contaminated environment
- person-to-person spread, often resulting in multiple people in one household becoming infected
Most large outbreaks of STEC are foodborne, commonly identified food vehicles include meat (for example, under-cooked burgers), salad vegetables or dairy products.
Norovirus causes diarrhoea and vomiting and is one of the most common stomach bugs in the UK. It’s also called the ‘winter vomiting bug’ because it’s more common in winter, but you can catch it at any time of the year.
Norovirus can be very unpleasant but usually clears up by itself in a few days.
You can normally look after yourself or your child at home.
Avoid going to your GP, as norovirus can spread to others very easily. Phone your GP practice or NHS 24 on 111 if you’re concerned or need advice.
You’re likely to have norovirus if you experience:
Some people also have a slight fever, headaches, painful stomach cramps and aching limbs.
The symptoms appear 1 to 2 days after you become infected and typically last for up to 2 or 3 days.
Go to NHS.UK for further information.
Phone 999 or go to A&E if you or your child:
- vomit blood or have vomit that looks like ground coffee
- have green vomit (adults)
- have yellow-green or green vomit (children)
- might have swallowed something poisonous
- have a stiff neck and pain when looking at bright lights
- have a sudden, severe headache or stomach ache
Phone 111 now if:
- you’re worried about a baby under 12 months
- your child stops breast or bottle feeding while they’re ill
- a child under 5 years has signs of dehydration – such as fewer wet nappies
- you or your child (over 5 years) still have signs of dehydration after using oral rehydration sachets
- you or your child keep being sick and cannot keep fluid down
- you or your child have bloody diarrhoea or bleeding from the bottom
- you or your child have diarrhoea for more than 7 days or vomiting for more than 2 days