Food poisoning types and treatments

Whilst the Food Standard Agency continually works towards promoting microbiological safety of our food throughout the entire food chain process, food poisoning still affects over one in three of the UK population at some point in their lives.


Although it’s not usually serious, food poisoning can certainly cause nasty symptoms which include sickness, diarrhoea and stomach pain. It can also have certain complications for more vulnerable types of people.


In this blog we take a look at the various types of food poisoning and how they’re capable of affecting our health.


What causes food poisoning?


Food poisoning can occur when food type becomes contaminated by certain bacteria such as salmonella, E.coli or another type of virus, such as the well-known norovirus.


Unfortunately, food can become contaminated at any stage during the production process and even by cooking it.  Some of the most common causes include:


  • Failure to cook food properly (particularly meats, poultry and raw shellfish)


  • Not storing foods in accordance with associated guidance – especially food which needs to be either chilled or frozen


  • Re-freezing food after it’s already defrosted


  • Leaving food exposed to warm temperatures


  • Eating food which has already gone past it’s “use by” date (consumers often fail to differentiate between “use by” and “best before” dates which can certainly have serious consequences)


  • Improper handling of food – particularly when handled by someone who is ill or has failed to wash their hands properly, since this can quickly lead to cross-contamination.


The importance of preventing of cross-contamination is often overlooked since it can take place in two main ways namely:


  1. Through ‘direct’ cross-contamination i.e. due to contact between raw food and ready-to-eat food during transport, storage or even the preparation process (for example, by storing raw meat above fresh sandwiches in a fridge, which allows potential for the juices to drop down).


  1. Through ‘indirect’ cross-contamination i.e. through a spread of bacteria from raw food to ready-to-eat food via food handlers, equipment or surfaces. Examples of indirect cross-contamination typically include via fridge door handles, knives, work surfaces, chef’s clothing, cloths and chopping boards – for example, if raw meat is being prepared on the same board as a salad without appropriate cleansing in-between.


What are the likely symptoms?


As we’ve already seen, food poisoning can cause an array of different symptoms which may include some, or all, of the following:


  • Sickness (vomiting)
  • Diarrhoea (or a sudden change in bowel movements)
  • Stomach cramps or pains
  • Feeling lethargic or generally ‘under the weather’
  • Loss of appetite
  • Aching muscles


In the vast majority of cases, these symptoms will pass within a few days but if they don’t then it’s advisable to consult your GP – particularly if you’re unable to sip fluids, since this can quickly lead to dehydration. You should also seek medical assistance if you’re pregnant, over the age of 60, have any other type of medical condition (such as diabetes) or the condition is affecting either a baby or infant.


What are the different types of infection?


Food contamination is usually caused by harmful bacteria, although it can also be caused by different viruses or parasites. Let’s take a look at the main ‘offenders’ in turn:


Campylobacter: This is, without doubt, the most common cause of food poisoning across the UK. This type of bacteria is usually found on raw or undercooked meat, but particularly chicken, which typically accounts for around 4 out of 5 cases.


According to the Food Standards Agency, it’s currently considered to be responsible for more than 280,000 cases of food poisoning each and every year and costs the UK economy around £900 million.


Symptoms for this particular strain of food poisoning usually take anywhere between two and five days to appear and symptoms generally last for just less than a week.


Salmonella: This type of bacteria has over 2,500 different strains and is again found in both raw or undercooked meat, as well as eggs, milk and other types of dairy product.


Unlike campylobacter, the symptoms for this type of food poisoning are often evident much quicker – usually within 12 hours – and symptoms can last anywhere between 4 to 7 days.


Listeria: Listeria is often found in chilled, ready-to-eat food, such as pre-packed sandwiches, cooked meats, pate and soft cheeses. Since these food types are often purchased as convenience foods, it’s important to consume them well before their “use-by” dates and never afterwards – particularly for pregnant women or other more vulnerable groups, such as the elderly and infants.


According to the Food Standards Agency, pregnant women are around 20 times more likely than other healthy adults to contract listeriosis and this, in turn, can lead to both miscarriage and birth complications. In the infant it’s also capable of causing stillbirth and life-long health problems – hence the need to get urgent medical advice can never be stressed enough.


Escherichia coli: More commonly referred to as “E.coli”, this type of food poisoning derives from bacteria found within the digestive systems of both animals and humans. Whilst most of the strains are harmless they can certainly cause serious illness and so the usual advice with regard to seeking medical advice still very firmly stands.


The vast majority of E.coli cases often occur after eating undercooked beef (particularly mince, burgers and meatballs) or drinking unpasteurised milk.


Generally speaking, you’re most likely to notice the symptoms of E.coli between 1 and 8 days after eating something contaminated and the symptoms can last anywhere between a few days and up to a few weeks, so it’s crucial to take as much fluid as possible during this time in order to avoid dehydration and/or weight loss.


The worse strain of E.coli is 0157.H7 which, in more severe cases, can cause kidney failure and even death. This is due to the fact that the infection is associated with haemolytic uremic syndrome (‘HUS’) which produces toxic substances capable of destroying red blood cells. In some cases, this will require hospitalisation for either kidney dialysis or blood tranfusions.


Shigella: This type of bacteria can contaminate any food type that has been washed in contaminated water. Symptoms will usually develop within a week of eating contaminated food and again, tends to last for several days.


The shigella germ is a family of bacteria which usually causes diarrhoea and is most commonly experienced in child-care settings or schools. It’s also quite common among foreign travellers since it’s particularly evident in developing countries.


Norovirus: Another type of virus which commonly causes diarrhoea is norovirus (also known as the ‘winter vomiting disease’) which is quite easily spread from person to person through contaminated food or water. Raw shellfish – and particularly oysters – are usually a common source of infection.


The incubation period for norovirus is typically between 24 and 48 hours and fortunately symptoms tend to pass within just a couple of days; although it can cause further complications for more vulnerable groups such as the very young and elderly people. Outbreaks of this virus are extremely common in semi-enclosed environments such as hospitals, nursing homes, schools and cruise ships.




Fortunately, in the vast majority of cases, food poisoning can easily be treated at home without having to seek any medical attention. That said, certain vulnerable groups are advised to be especially careful – for example, pregnant women, infants, the elderly and those with an existing medical condition (such as diabetes, kidney failure and so on).


If you find yourself in the unfortunate position of having food poisoning (or even simply suspect you might have it) then it’s important not to spread the infection and for this reason, you’re well advised not to prepare food for others until such time as your symptoms have fully passed. During this time it’s also advisable to have contact with as few people as possible so a couple of days in bed might well be just what the doctor ordered!