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Food poisoning and infectious diseases

Our Food, Health and Safety Team routinely investigates cases of food poisoning and other notifiable infectious diseases. These are usually reported to us by Public Health England following receipt of positive results from their laboratory. This normally arises as a result of people contacting their GP and submitting a faecal sample for examination.

Our environmental health officers may decide to investigate the notification to try to prevent the spread of the illness within the home and the community and to try to establish the source of the infection. The decision as to whether or not to carry out an investigation will depend on the cause of the illness, whether a positive result confirming an infectious disease has been received from the laboratory, the number of people affected, the severity of the illness, and any delay between the start of the illness and receipt of the report.

Where a decision has been made to investigate, the environmental health officer will contact the person(s) with the symptoms, either by post, telephone or by visiting them and will ask them questions regarding:

  • what and where they've eaten prior to their illness;
  • details of their symptoms;
  • whether they've been on holiday abroad;
  • whether or not their GP has taken a faecal sample and;
  • whether anybody else they ate with also experienced any symptoms. We may request that person to provide a faecal sample.

Bacteria and symptoms

The incubation period (time taken from becoming infected to feeling unwell) varies with each type of organism and in some cases can be as long as two weeks or more. If you suspect you are suffering from food poisoning, it is important to realise that the last meal you ate may not be the cause of your symptoms. The Bacteria and Symptom Chart below gives details on incubation periods and symptoms.

Bacteria and symptom chart

Bacteria Source Vehicle Route Symptoms Onset Period Recovery
Salmonella Poultry, meat, raw egg products, human and animal excreta, carriers. Utensils, work surfaces, hands. Contamination from raw to cooked / ready-to-eat food. Diarrhoea, vomiting, fever. 6 to 72 hours. Usually 12-24 hours 1 to 7 days
Staphylococcus Toxin Skin, nose, spots and boils. Hands, coughs, sneezes, open infected wounds. Cooked / ready-to-eat food. Vomiting, diarrhoea, abdominal cramps 2 to 6 hours Rapid
Campylobacter Animals, including domestic pets, birds, contaminated water.

Raw or undercooked meat especially poultry,

unpasteurised milk, bird pecked milk on doorsteps, untreated water, pets with diarrhoea.

Undercooked foods, faecal-oral route. Abdominal cramp, diarrhoea, often bile stained. Vomiting uncommon.

1 to 11 days

(usually 2 to 5 days)

3 days to 3 weeks
Bacillus Cereus Cereals, environment Dirty surfaces, hands, utensils. Cooked rice, corn flour, sauces Acute vomiting, some diarrhoea. 8 to 16 hours 12 to 48 hours
Clostridium Perfringens Animal excreta, human excreta, raw meats, soil and dust. Soil, dust, utensils, work surfaces, hands, unwashed vegetables and fruit. Warm storage, slow cooking, braised, stewed and steamed foods. Abdominal pain, diarrhoea.

8 to 22 hours

(usually 12 to 18 hours)

12 to 48 hours
Clostridium Botulinum Soil, meat, fish, including smoked. Imperfectly processed canned and bottled foods Airtight packaged food for example: canned and bottled foods Fatigue, dizziness, headache, possible death

12 to 96 hours

(usually 12 to 36 hours)

Very slow, can be fatal
E Coli Animal and human excreta, water. Hands, utensils, surfaces. Raw foods to cooked / ready-to-eat foods. Diarrhoea (mucus and blood) 1 to 6 days 1 to 5 days
Cryptosporidium Animal and human excreta, contaminated water. Contact with infected animals, humans, water. Contact with infected animals, humans, water. Profuse, watery diarrhoea. 2 to 5 days Up to 4 weeks
Giardia Animal and human excreta. Hands, surfaces, water. Person to person. Diarrhoea, abdominal cramps. 5 to 25 days Up to several weeks

Not all cases of infectious disease are due to contaminated food, many are caused by viruses that often have the same symptoms of food poisoning and spread very quickly from one person to another. These types of infection are especially common in babies and young children who pick them up from other children at nurseries, playgroups and school. Other sources of infection include farm animals and household pets.

What should I do if I suspect I have food poisoning?

If you suspect you are suffering from an infectious disease, including food poisoning, it is recommended that you consult your GP as soon as possible, who might ask you to submit a sample for examination.

If a person with symptoms is a food handler or health care/nursery worker who has direct contact or contact through serving food, with highly susceptible patients or persons in whom an intestinal infection would have serious consequences, they should not return to work until they are symptom-free for 48 hours. They must also inform their employer of their symptoms.

Parents or guardians of children aged under 5 years or children or adults unable to implement good standards of personal hygiene, are advised to keep them away from school or other establishments until they have also been symptom-free for 48 hours.

The main causes of food poisoning

The main causes of food poisoning are:

  • preparing foods too far in advance
  • not cooking foods properly
  • not defrosting foods correctly
  • storing foods incorrectly (ie too warm) so that bacteria is able to quickly grow
  • cross contamination of foods after cooking
  • infection from people handling foods due to poor hygiene.

How do I avoid food poisoning

Whilst different types of germs and foodstuffs are associated with different types of illness, by following some simple rules you can help yourself and your families to stay safe:

  • Always store raw meat and poultry in a covered container at the bottom of the fridge so that it cannot drip onto other foods.
  • Ensure that your fridge is clean and operating between 0 and 4 degrees centigrade
  • Always defrost meat, fish and poultry thoroughly before cooking.
  • Cook food thoroughly and if reheating, ensure it is piping hot before eaten.
  • If hot food is not to be eaten immediately, cool it quickly (within 90 minutes and refrigerate).
  • Ensure that work surfaces, cloths, utensils and chopping boards are cleaned thoroughly (between use) especially after being used for raw meat, poultry or fish.
  • Keep any cuts/wounds covered with a waterproof dressing when preparing food.
  • Always wash salad before eating it to remove dirt.
  • Keep dogs, cats, etc. out of the kitchen when preparing food and always wash their bowls separately to yours.
  • Always wash your hands with soap and hot water before preparing food or handling a baby, after going to the toilet, after playing with pets, after changing nappies, caring for people suffering from diarrhoea or vomiting, handling soiled bedding, etc.
  • Never drink untreated water from lakes or streams as it may be polluted.

You can discuss any specific queries or concerns you may have with an environmental health officer, see contact details below, or you can read about Infectious Diseases on GOV.UK.