In this article
Many harmful pathogens can contaminate food and cause a range of food.
The number of reported cases is thought to be significantly lower than the actual number. This is because not everyone with symptoms presents to their doctor for the illness to be recorded.
The range of foodborne illnesses (or diseases) is collectively known as food poisoning and occurs from eating food contaminated with microorganisms. As these tiny pathogens enter the body, they can rapidly multiply and can cause infection. Some can also produce toxins in large numbers, which can result in intoxication. Food poisoning can also be caused by eating food contaminated with chemical hazards.
Food poisoning in health and social care
Food poisoning is very unpleasant indeed and causes a range of horrible symptoms. In a health and social care setting, food poisoning can be serious due to the vulnerability of people being cared for and supported.
Food poisoning is a risk that everyone should be aware of, especially care providers and food handlers. They should know what foodborne illnesses are and the causes, as they have a significant role in preventing food poisoning in their settings.
They also have legal duties, under the Food Safety Act 1990 and associated food safety and hygiene regulations, to ensure that any food provided to service users is safe for them to eat. These duties are extended by health and social care laws, which require infection prevention and control.
Food poisoning can affect anyone at any time. Even the healthiest of people can suffer from food poisoning, but most will recover after a short period of illness.
There are some groups of individuals who have an increased vulnerability to food-related illnesses. This is usually due to their weakened immune systems.
For a variety of reasons, they are more likely to:
- Be affected, as a smaller number of microorganisms (load) can cause illness;
- Experience more severe symptoms; and
- Become seriously ill or even die from the symptoms.
Vulnerable groups can include:
- Children under 5 years old.
- Pregnant and breastfeeding women.
- Adults over 65 years old.
- People with existing illnesses.
- People with already weakened immune systems.
In your health and social care setting, you are likely to prepare and handle food for people in some of the above groups. Always be mindful of the increased risk of food poisoning in these individuals.
Food poisoning symptoms
When an individual eats contaminated food, their body tries to get rid of it quickly, which results in symptoms presenting in the person.
Symptoms of food poisoning can occur in a matter of hours, days or weeks after eating contaminated food. The time between eating contaminated food and symptoms showing is known as the incubation period.
Different microorganisms will have different incubation periods, e.g. a salmonella infection has an incubation period of approximately 12–72 hours. Listeria, which is a bacteria, can take up to 70 days to incubate before a person starts to experience symptoms.
Common symptoms of food poisoning include:
- Stomach cramps.
- High temperature.
The symptoms of food poisoning usually pass within a week and, in most cases, after a few days. For those who are more vulnerable, it can take longer to clear and may require medical intervention. Vomiting and diarrhoea can cause dehydration, which is a severe risk for vulnerable groups.
It is not always the last thing a person ate that made them ill. In fact, this is rarely the case, which can make it difficult to pinpoint the cause of food poisoning.
Food poisoning bacteria
The severity of food poisoning will depend on the microorganism type and the number (the load). The majority of food poisoning cases are caused by bacteria and a small number of viruses.
Some examples of food poisoning bacteria include:
- Found in a wide variety of foods, but most common in raw meat, undercooked poultry, unpasteurised milk, cheese and undercooked eggs.
- It can cause an infection known as salmonellosis. It is a common cause of food poisoning.
Escherichia coli (E. coli)
- Found in the faeces and intestines of animals and humans.
- Common in raw and undercooked meats, raw leafy vegetables and salads, untreated water or unpasteurised milk.
- E. coli O157: H7 is particularly dangerous, as it can also produce a toxin.
- Found in a wide range of foods, e.g. unpasteurised milk and dairy products, soft cheeses, salads, chilled ready-to-eat foods (deli meats and pate), raw/undercooked meat, poultry and seafood.
- It can cause listeriosis, which is a serious infection.
- Found on people’s skin, hair, wounds, sores, septic spots and in the nose.
- It can be transferred to food by poor hygiene practices.
- Found in cooked meats and poultry, unpasteurised dairy products and hand-made ready-to-eat foods.
- Found in the guts of animals.
- It is common in raw or undercooked poultry, unpasteurised dairy products and untreated water.
- It can cause an infection known as campylobacteriosis.
- Common in the environment and faeces.
- It is typically found in beef, poultry, casseroles and gravies.
- It forms spores that can produce toxins.
- Found in the environment and mainly in soil.
- Cooked rice is one of the foods most associated with B. cereus.
- It forms spores that can produce toxins.
Food poisoning viruses
As you have seen, many different types of bacteria can cause food poisoning, and it is the most common cause.
Viruses can also cause food poisoning. The most common one is the Norovirus, which is also known as the winter vomiting bug. According to the Food Standards Agency, it causes an estimated three million cases of diarrhoea and vomiting each year, and 380,000 cases are linked to food. In care homes, it is the most common cause of gastrointestinal infection.
Norovirus is spread by humans via the oral-faecal route to food and drinks, usually through poor hygiene practices. It is common in shellfish, leafy vegetables, fruit and ready-to-eat foods. The virus does not multiply in food, but it can survive on it for long periods.
The winter vomiting bug is highly contagious, and in a residential health and social care setting, an outbreak can have serious consequences. Even though it is usually a mild illness, it can be dangerous for more vulnerable people, such as the elderly, due to complications associated with dehydration.
Certain foods carry a higher risk of food poisoning, as they provide the ideal conditions for harmful pathogens to grow and multiply.
High-risk foods include:
- Ready-to-eat foods that don’t require further cooking or processing.
- Raw foods that contain harmful pathogens due to their nature, e.g. meat.
- Foods that contain spores that may not be killed by cooking or reheating.
- Foods that are usually moist and have a high protein content.
- Foods that require time and temperature controls.
- Foods that spend any time in the danger zone.
- Foods that can become easily contaminated.
Examples of high-risk foods:
- Eggs and any dishes containing eggs, e.g. soft boiled, mayonnaise, quiche or mousse.
- Cooked rice.
- Pulses (can contain natural toxins).
- Cooked meat and poultry, e.g. beef, pork, ham, lamb, chicken and turkey.
- Dairy, e.g. milk, cream, artificial cream, custards, unpasteurised milk, ripened soft & moulded cheeses.
- Cooked meat products, e.g. meat pies, pate and meat stock & gravy.
- Shellfish and other seafood, e.g. mussels, cockles, cooked prawns and raw oysters.
- Fish, e.g. mackerel, tuna, anchovies and herrings.
- Raw and prepared fruit, salads and vegetables.
High-risk foods – precautions
You must take extreme care when preparing and handling high-risk food, especially when caring for anyone classed as vulnerable.
- Restrict the time food spends in the danger zone as much as possible.
- Adopt high standards of personal hygiene, e.g. wash your hands before handling high-risk foods.
- Try to avoid touching the food by hand and use clean and disinfected utensils whenever possible to prevent cross-contamination.
- Use clean boards, knives and utensils between foods to prevent cross-contamination.
- Store foods properly, e.g. keep them covered in the refrigerator under 5°C until required and don’t use any beyond the use-by date.
- Keep raw and ready-to-eat foods separate to avoid cross-contamination.
- Cook foods properly to kill any harmful bacteria.
- Limit the time taken to prepare high-risk foods as much as possible.
- Always buy foods from reputable suppliers and assurance schemes.
Some foods have a lower risk of food poisoning, as they do not provide ideal conditions for harmful pathogens to grow and multiply.
Low-risk foods include:
- Foods with high sugar, fat and salt content, e.g. jams, sweets and chocolate.
- Foods with high acidity, e.g. pickled onions, vinegar and citrus fruits.
- Fermented foods, e.g. salami and pickles.
- Unopened tinned foods, e.g. baked beans and soups.
- Foods with low moisture (dry goods), e.g. bread, cereals, biscuits, cakes (not cream) and flour.
- Preserved foods, e.g. some types of smoked fish.
Even though these have a lower risk of food poisoning, you must still follow good hygiene practices. Also, some of these foods will still contain allergens, so they are not risk-free.
Do not be tempted to provide service users with just low-risk foods. They need a balanced diet to maintain good nutrition, which means they will need fresh foods, which will be in the higher risk category. As long as you follow good hygiene measures and food safety practices, it should reduce the risk of food poisoning.
Conditions for microbial growth
To understand how to keep food safe and prevent food poisoning, we need to know how and why bacteria grow in food.
Microorganisms need certain conditions to be able to survive and grow. Various factors can encourage the growth of harmful pathogens in food, such as:
- Temperature – Warmer foods, e.g. bacteria grow best between 25°C and 40°C.
- Moisture – Foods with higher moisture content.
- pH levels (acidity & alkalinity) – Less acidic foods.
- Time – If food is left longer in the danger zone, it will give bacteria more time to multiply to harmful levels.
All microorganisms are different; they will grow in different ways and varying conditions. They all need food, moisture, warmth and time. Most will also need oxygen, but some can grow without it.
Temperature and time need to be controlled to prevent pathogens from growing and multiplying. This can be achieved by keeping food out of the danger zone by storing, preparing and cooking it correctly.
Common causes of food poisoning
A common cause of food poisoning is food becoming contaminated with bacteria. It usually happens as a result of:
- Not cooking food or reheating it thoroughly – for example, not cooking chicken or burgers through to the core to a suitable cooking temperature.
- Cross-contamination – transferring bacteria from raw foods to cooked or ready-to-eat foods. For example, preparing raw chicken on a cutting board and then preparing sandwiches on the same board.
- Poor personal hygiene – for example, transferring bacteria onto food by coughing or sneezing over it and touching food and not washing hands.
- Being ill whilst handling food – if a handler is ill with diarrhoea and or vomiting, it can be passed to others.
- Poor storage practices – for example, chilling food too slowly or leaving it out at room temperature for too long.
- Unclean kitchen and equipment – for example, poor waste disposal, dirt left on surfaces and equipment not properly cleaned and disinfected.
- Eating food after its use-by date – high-risk foods have use-by dates for a reason. It indicates the time up to which food is safe to eat.
- Contaminated water – from wastewater or sewage. Using water in preparing food from a source that is not safe for drinking. Also, washing equipment and utensils in contaminated water, which are used to handle food.
To ensure food is safe to eat and to prevent food poisoning, there are four main things you should remember. These are known as the 4Cs of hygiene.
- Cleaning – Ensure you maintain a high standard of cleanliness and tidiness in and around food areas within your setting at all times. Clean and disinfect equipment, surfaces and utensils after use and between tasks, particularly after handling raw food. Use the clean as you go approach, which will help keep areas constantly clean and tidy.
- Chilling – Foods that need to be chilled should be kept cold. Chilled foods should be kept in a refrigerator at temperatures of 5°C or below. Always store foods correctly and follow the storage instructions.
- Cooking – Foods that require cooking before being eaten should always be heated thoroughly. Cook food until it has reached at least 70°C and stayed at that temperature for 2 minutes. Food should be piping hot all the way through. In addition to probe thermometer checks, use visual cues such as checking for colour change, boiling and steam.
- Cross-contamination – This is one of the most common causes of food poisoning. Avoid causing cross-contamination by following good food hygiene practices at all times. Be aware of transferring bacteria and viruses from yourself and any raw foods to the food you are preparing. Store raw foods separately and away from ready-to-eat and cooked foods.