Recognising and Preventing Common Foodborne Illnesses

Foodborne illnesses, more commonly known as food poisoning, are infections or irritations of the gastrointestinal tract caused by consuming food or beverages that are contaminated with harmful bacteria, viruses, parasites or toxins. These contaminants can enter food at various stages, including production, processing, preparation, storage and handling. Contamination often occurs because of improper food handling practices, inadequate cooking or cross-contamination.

Globally, foodborne illnesses represent a significant public health challenge. In the UK alone, the Food Standards Agency (FSA) estimates approximately 2.4 million cases of food poisoning every year. The economic impact is also considerable, with costs stemming from healthcare, sick days from work, lost productivity and reduced consumer confidence. The FSA estimates that food poisoning costs the UK economy more than £9.1 billion annually. Not only can food poisoning make people ill and negatively impact the economy, but in more serious cases, food poisoning can lead to hospitalisation, long-term health complications and even death. 

Recognising and preventing foodborne illnesses is essential for safeguarding public health. By understanding common causes, symptoms and prevention methods, individuals, food businesses and communities can reduce the risks associated with contaminated food and promote healthier and safer food practices.

Common Foodborne Illnesses

Foodborne illnesses are caused by various pathogens that can contaminate food and lead to a range of symptoms. The most common foodborne illnesses are:

Salmonella 

Salmonella is an infection of the Salmonella bacteria. Salmonella is a family of bacteria that live in the guts of birds and animals. There are more than 2,500 strains of Salmonella bacteria and this is the most common cause of food poisoning.

Symptoms

Nausea, vomiting, diarrhoea, fever and abdominal cramps. Symptoms often appear within 6 to 48 hours after consuming contaminated food and can last for several days.

Common sources

Salmonella is commonly found in poultry, eggs, meat, unpasteurised milk and contaminated produce. Improper handling or undercooking of these foods can lead to contamination. Salmonella can also be found in fruits and vegetables if these foods have been stored or harvested near animal manure. A person who is infected by Salmonella (either as a carrier or someone who is actively ill) can also contaminate foods, for example, by not washing their hands, which can spread the bacteria to other people and cause a larger outbreak.  

E. coli (Escherichia coli) 

E. coli, sometimes called Shiga toxin-producing Escherichia coli (STEC), is a bacterial infection caused by E. coli bacteria. This type of bacteria is found in the gut and faeces of cattle and other animals and while some types of E.coli can be relatively harmless, others can cause a range of infections, including food poisoning.

Symptoms

Severe diarrhoea (sometimes bloody), abdominal cramps and vomiting. Some strains, such as E. coli O157, can cause haemolytic uremic syndrome (HUS), a severe condition that can lead to kidney failure.

Common sources

E. coli is often associated with minced meat, raw milk, contaminated water and fresh produce. It can be caught by eating contaminated foods (e.g. undercooked meat or unwashed vegetables), touching infected animals or coming into contact with their faeces, drinking or swimming in contaminated or untreated water or having contact with people who have E. coli. Cross-contamination during food preparation can increase the risk of E. coli infections.

Listeriosis 

Listeriosis is a rare type of infection that occurs when people eat food contaminated with listeria bacteria. For many people, listeriosis causes mild symptoms; however, it can be extremely dangerous during pregnancy and can lead to miscarriage, stillbirth or preterm labour. People with weakened immune systems and older people are also at higher risk of listeriosis. 

Symptoms

Fever, muscle aches, nausea and diarrhoea. In severe cases, Listeria infection can spread to the nervous system, causing headaches, stiff neck, confusion and loss of balance. 

Common sources

Most commonly, listeriosis occurs by eating chilled, ready-to-eat food, including cold, sliced meat, cured meat, smoked fish, mould-ripened cheeses (e.g. camembert and brie), pâté, pre-made sandwiches and pre-cut fruit that is affected by listeria bacteria. Listeria can survive at refrigerated temperatures, making proper storage critical for prevention. Less commonly, listeria can also spread from person to person, e.g. if someone with listeriosis doesn’t wash their hands when handling food.

Norovirus 

Norovirus is a common type of stomach bug. Although norovirus can occur at any time of the year, it is widely called the ‘winter vomiting bug’, as cases are typically higher in winter. Norovirus can survive outside of the body for several days, making it particularly contagious. Outbreaks are common in areas where lots of people have close contact, including hospitals, schools, nurseries and care homes. 

Symptoms

Diarrhoea, vomiting, nausea and stomach pain. Norovirus is highly contagious and can cause symptoms to appear rapidly, typically within 12 to 48 hours after exposure.

Common sources

Norovirus can be found in food handled by infected individuals. It can spread if small particles of vomit or stools from an infected person enter your mouth, e.g. if someone with the virus breathes out particles of the virus near you or prepares food that you eat. It spreads easily through surfaces and direct contact, making strict hygiene practices essential in food preparation areas.

Campylobacter 

Campylobacter is a type of germ that lives in the gut of birds and animals. It has a low infective dose, meaning that you only need to come into contact with a small number of bacteria to get ill. It typically causes a short-lived bout of food poisoning but young children (under five), the elderly and people with weak immune systems can experience long-term severe illness.  

Symptoms

Diarrhoea (sometimes bloody), fever, abdominal cramps, nausea and vomiting. Symptoms usually appear within 2 to 5 days of exposure and can last up to a week.

Common sources

Campylobacter is frequently found in undercooked poultry, unpasteurised dairy products and contaminated water. Proper cooking and avoiding cross-contamination during food preparation are crucial to prevent infection.

Clostridium perfringens 

Clostridium perfringens is a spore-forming bacterium that thrives in environments with little or no oxygen, known as anaerobic conditions. This bacterium is naturally found in the intestines of humans and animals, as well as in soil, sediment and areas where food is prepared, such as kitchens. 

Symptoms

Sudden onset of abdominal cramps and diarrhoea. Symptoms usually appear within 6 to 24 hours after consuming contaminated food and often resolve within a day.

Common sources

This bacterium is commonly found in meats, poultry and gravies that have been left at room temperature for too long. It is highly resistant to heat, meaning it can survive the cooking process and can grow and multiply in food that is improperly stored or heated. If the food is eaten without adequate reheating, the bacteria release toxins in the intestines, leading to illness. Ensuring hot foods are kept above 63°C and cold foods below 8°C can reduce the risk of contamination.

Symptoms and When to Seek Medical Attention

Foodborne illnesses often present with similar general symptoms. Food poisoning severity can vary from mild, short-term discomfort to life-threatening conditions. While many cases resolve on their own, certain bacteria and complications (e.g. dehydration or kidney failure) can escalate. Recognising the signs and knowing when to seek medical help can make a significant difference, especially for high-risk individuals. 

Common symptoms of foodborne illnesses include:

• Nausea
• Vomiting
• Diarrhoea 
• Stomach cramps 
• A temperature of 38°C or above
• Generally feeling unwell, such as aches, chills and tiredness

In some cases, specific foodborne illnesses may have unique symptoms that can help identify the type of food poisoning you are experiencing. For example:

• Bloody diarrhoea: Often associated with E. coli infections and certain strains of Campylobacter, bloody diarrhoea can indicate more severe intestinal inflammation and potential complications.
• Severe muscle pain: Muscle pain is common in Listeria infections, particularly in vulnerable groups such as those who are pregnant and the elderly.
• Persistent vomiting: Seen in cases like norovirus infection, where symptoms often come on suddenly and cause repeated vomiting. Vomiting typically stops within 2-3 days.

The severity of symptoms can vary widely depending on the specific pathogen, amount of contaminated food consumed and individual factors such as age and overall health. 

While mild cases of foodborne illness usually resolve on their own within a few days, certain symptoms or circumstances indicate the need for medical attention. It is recommended to seek medical help if:

• Symptoms persist for more than a few days: If symptoms like diarrhoea or vomiting do not subside after 2-3 days, it may be a sign of a more serious infection.
• There are signs of dehydration: Symptoms of dehydration include dry mouth, excessive thirst, reduced urination, dark-coloured urine, dizziness and weakness. Severe dehydration, especially in children or elderly individuals, requires prompt medical treatment.
• You have a high fever: A temperature of 38°C or higher, especially when accompanied by other symptoms, may require medical attention. If you have been treating the high temperature at home and is not getting any better or the fever is getting worse, medical attention is highly recommended. 
• There is blood in stools or vomit: Blood in stools or vomit can indicate severe intestinal infection or damage and should not be ignored.
• You have severe abdominal pain: Persistent or intense abdominal pain, especially with other symptoms, may require medical evaluation.

Some individuals are more vulnerable to complications from foodborne illnesses and should take extra precautions and seek medical advice at the onset of symptoms. This includes:

• Young children: Due to their developing immune systems, young children under the age of 5, are at higher risk for severe symptoms and complications, including dehydration. Infants are at the highest risk of further complications. 
• Pregnant women: Certain foodborne pathogens, such as Listeria, pose specific risks during pregnancy and can potentially lead to miscarriage, stillbirth or infection of the newborn.
• Elderly people: Older adults may have weaker immune systems, which make it harder for them to fight off infections. They are also more susceptible to dehydration and other complications.
• Immunocompromised people: People with weakened immune systems, such as those undergoing cancer treatments, organ transplant recipients or individuals with chronic illnesses (e.g. diabetes, HIV or AIDS), are more susceptible to foodborne pathogens and complications.

Key Strategies for Preventing Foodborne Illnesses

Preventing foodborne illnesses relies on a combination of personal hygiene practices, safe food handling, proper storage and thorough cleaning techniques. By following these hygiene, handling, storage and sanitisation guidelines, we can significantly reduce the risk of foodborne illnesses and create safer environments for food preparation and consumption. The most effective ways of preventing food poisoning include:

Personal Hygiene

Good personal hygiene is essential during every stage of food handling. Good personal hygiene helps to prevent bacteria, viruses and other contaminants from spreading from people to food and helps to keep food safe. Whether you are preparing food at home, you work in the food industry or you are handling food for another reason, there are several ways you can ensure good personal hygiene:

Handwashing

Washing hands thoroughly is essential for preventing the spread of bacteria and viruses to food. Always wash hands with soap and warm water for at least 20 seconds before and after handling food, after using the restroom and after touching surfaces like phones or doorknobs. Proper hand hygiene can prevent many common foodborne pathogens from spreading.

Handling food with care

Maintaining clean workspaces, utensils and surfaces reduces cross-contamination. Ensure all surfaces, cutting boards and utensils are clean before starting to prepare food and avoid touching your face or hair while handling food. This reduces the risk of contaminating food with pathogens from surfaces or skin.

Check your own health

If you are experiencing any symptoms of illness that could be transmitted through food, such as vomiting, diarrhoea or nausea or you have any infected wounds, you should not handle food, particularly in a professional capacity (e.g. at work). It is okay to prepare food for yourself but do not handle any food that will be eaten by other people, including your family members, as this could infect other people. If you have symptoms of illnesses such as norovirus, which easily spreads between people, you should stay home and avoid contact with other people for at least 48 hours after your symptoms have stopped. 

Safe Food Handling and Preparation

Food handling and preparation is a key stage where contamination can occur. Food that is not cooked correctly and thoroughly can harbour harmful bacteria that can cause foodborne illnesses. Raw meats and other high-risk foods can also contaminate other foods with bacteria, which can be extremely dangerous. For example, if raw meat comes into contact with ready-to-eat foods, such as salad, sandwich meat or cheese, eating these foods (that are typically eaten cold and not cooked) could cause food poisoning, as the harmful bacteria will not be destroyed in the cooking process. Some ways to ensure safe handling and preparation include:

Cook food to correct temperatures 

Cooking food to safe internal temperatures is one of the most effective ways to kill harmful bacteria. Use a food thermometer to confirm that food has reached a safe cooking temperature all the way through and remains at that temperature for a safe amount of time. The FSA recommends the middle of food should reach 70°C for at least two minutes or:

• 60°C for 45 minutes
• 65°C for 10 minutes
• 70°C for 2 minutes
• 75°C for 30 seconds
• 80°C for 6 seconds

Avoid cross-contamination

Cross-contamination happens when raw food, especially meat, transfers bacteria to ready-to-eat foods. To prevent this:

• Keep raw meats separate from ready-to-eat foods during storage and preparation.
• Store raw meat at the bottom of the fridge to prevent its juices from dripping onto other food.
• Use separate cutting boards for raw and cooked foods and label them if possible.
• Wash hands, utensils and surfaces after handling raw meat or poultry.

Proper Food Storage

Maintaining safe temperatures during food storage is essential for preventing foodborne illnesses. Incorrect storage temperatures can result in harmful bacteria growing and multiplying and can cause more severe food poisoning. Tips for proper food storage include:

Refrigeration and freezing

Storing perishable foods at the correct temperatures prevents bacterial growth. To safely store foods, you should:

• Refrigerate perishable items below 5°C.
• Freeze items at -18°C for long-term storage.
• Label foods with purchase or preparation dates and practise First In, First Out (FIFO) to ensure older items are used before newer ones. This helps to reduce spoilage and waste.

Defrosting safely

Proper thawing methods prevent bacteria from multiplying as food warms. Defrost food in the refrigerator or under cold running water. Food can also be defrosted using the ‘defrost’ setting on the microwave if you plan to cook it immediately. Avoid thawing food at room temperature, as this encourages bacterial growth.

Cleanliness and Sanitisation

Following good cleaning practices is an effective way to keep food safe. After each use, especially when handling raw meat, wash cutting boards, knives, countertops and other utensils with hot, soapy water. Rinse thoroughly and dry with a clean towel. Use a food-safe sanitiser or a solution of one tablespoon of bleach per gallon of water on surfaces and utensils for added protection.

Consider using separate cutting boards for different food types (e.g. one for raw meat and another for fruits and vegetables) to minimise cross-contamination, but if this is not possible, ensure items that come into direct contact with high-risk foods are thoroughly cleaned and sanitised. 

Special Considerations for High-Risk Groups

Certain individuals are more vulnerable to foodborne illnesses, including women who are pregnant, young children, elderly individuals and people with weakened immune systems. Because foodborne illnesses can have more severe or long-lasting effects on these populations, extra caution is essential. 

Below are some tips for these groups to help minimise the risks of foodborne illness.

Pregnant women

Pregnancy, at any stage, makes you particularly susceptible to Listeria and Toxoplasma infections, which can lead to serious complications, including miscarriage, stillbirth and pre-term labour. Food safety tips to follow during pregnancy include:

• Avoid high-risk foods, such as raw or undercooked seafood (e.g. sushi), unpasteurised milk and dairy products and deli meats or hot dogs unless they are reheated to steaming hot.
• Avoid soft cheeses like Brie, Camembert, blue-veined cheeses and queso fresco unless labelled as made with pasteurised milk.
• Thoroughly wash all fruits and vegetables before eating, even if they are prepackaged and labelled as ready-to-eat.
• Cook meat, poultry and eggs to safe internal temperatures to kill harmful bacteria.

Young children

Infants and young children are more vulnerable to dehydration from vomiting or diarrhoea caused by foodborne illness. Their immune systems are also not as developed as those of adults, which makes it harder for them to fight off infections. Safety tips for young children include:

• Avoid raw or undercooked eggs (including foods like raw cookie dough) and raw seafood.
• Refrain from giving children unpasteurised milk or juices, as they can contain harmful bacteria.
• Be cautious with foods like honey for infants under one year, as it can contain Clostridium botulinum spores, which can lead to infant botulism.
• Ensure leftovers are thoroughly reheated and stored correctly to prevent bacterial growth.

Elderly people

Elderly adults have weaker immune systems and are more susceptible to complications from foodborne illnesses. Chronic health conditions, such as diabetes or kidney disease, can further increase risks. Safety tips for older people include:

• Avoid consuming high-risk foods, including raw shellfish, undercooked meats and unpasteurised dairy products.
• Use a food thermometer to check the internal temperature of cooked foods to ensure they are safe to eat.
• Practise vigilant handwashing and avoid cross-contamination by using separate cutting boards and utensils.
• Consider avoiding cold deli salads, like those made with eggs, tuna or chicken, which can harbour bacteria if not stored and handled properly.

People with weakened immune systems

People with compromised immune systems (such as those undergoing chemotherapy, transplant recipients or individuals with HIV or AIDS) face a higher risk of severe illness and complications from foodborne infections. Safety tips include:

• Steer clear of raw or undercooked animal products, including meat, seafood and eggs.
• Avoid unpasteurised dairy and juices, which may harbour bacteria and other pathogens.
• Use extra caution when handling raw fruits and vegetables. Wash thoroughly or consider cooking them, as cooking kills bacteria.

The following high-risk foods should generally be avoided by vulnerable populations, as they are more likely to contain pathogens that could lead to foodborne illnesses:

• Raw shellfish (such as oysters, clams and mussels).
• Undercooked or raw meats (like rare steak or sushi).
• Unpasteurised milk and dairy products.
• Soft cheeses made from unpasteurised milk, unless confirmed to be pasteurised.
• Cold-cured meats, such as salami, pepperoni, chorizo and prosciutto unless cooked until steaming.
• Hot dogs unless cooked until steaming.
• Cold smoked or cured fish, e.g. smoked salmon or gravlax, unless it has been cooked until steaming. 
• Raw eggs or foods made with them (e.g. certain sauces, cookie dough, homemade ice cream).
• Sprouts, such as alfalfa or bean sprouts, are often linked to E. coli and Salmonella outbreaks due to the humid conditions needed for sprouting, which encourage bacterial growth.

By taking these extra precautions, high-risk individuals can significantly reduce their chances of contracting foodborne illnesses.

Reporting and Responding to Outbreaks

Timely recognition and response to a foodborne illness outbreak are crucial in preventing the illness from spreading further within communities. In the UK, there are specific steps and protocols for identifying, reporting and responding to suspected outbreaks.

A foodborne illness outbreak occurs when two or more people experience similar symptoms after consuming the same food or drink contaminated with pathogens. Common signs of an outbreak within a community may include:

• Sudden onset of illness: An increase in cases of symptoms like vomiting, diarrhoea and stomach cramps among people who have consumed food from a specific source (e.g. at a restaurant or event).
• Pattern of symptoms in a group: If people in a household, workplace, school or community event experience similar symptoms, this may indicate an outbreak linked to a specific food or water source. Alternatively, it could indicate a stomach bug, such as norovirus. 
• Reported cases in local media or public health alerts: The UK Health Security Agency (UKHSA) monitors and investigates foodborne illness cases. When there is an unusual increase in cases, the UKHSA may issue public health warnings.

If you suspect that you or others may have foodborne illness, it may be necessary to report it. Reporting helps local authorities identify, investigate and contain outbreaks to prevent others from becoming ill. In the UK you can report suspected food poisoning or a contaminated food product to the environmental health department at your local council. 

The Food Standards Agency (FSA) works with the local authority to ensure food safety and hygiene in England, Wales and Northern Ireland. They run a Food Safety Team that is responsible for food businesses in your local area. This team is responsible for investigating any reports of foodborne illnesses or food safety issues in businesses and can take action if food premises are involved. If an outbreak is suspected on a larger scale, the UKHSA may step in to investigate and coordinate responses. You can check their website for any ongoing outbreak alerts or advice.

By reporting suspected cases, seeking medical advice and following public health guidance, individuals and communities can play a crucial role in containing foodborne illness outbreaks and preventing further spread. It can be helpful to keep a food diary by writing down what you ate and drank, along with the times of consumption, symptoms and their onset. This information is helpful to healthcare providers and investigators trying to identify the food source responsible for the illness. 

If you suspect a particular food may be contaminated, keep it in a sealed container and label it. Do not consume any more of it. If asked by health authorities, this food can be tested for pathogens to confirm contamination. If the UKHSA or local authorities release guidance, follow it carefully. This may include avoiding certain foods, practising specific hygiene measures or monitoring for symptoms. Let others know if you suspect that a foodborne illness may have originated from a shared meal or event, so they can monitor for symptoms and take any recommended precautions.

Once a suspected outbreak is reported, authorities work to investigate and mitigate the spread. This generally includes:

• Contact tracing and testing: Investigators may interview affected individuals and test remaining food samples to trace the source of contamination.
• Environmental health investigations: Environmental health officers may inspect the implicated premises (such as a restaurant or food supplier) for hygiene and safety compliance, including food handling and storage practices.
• Public alerts and recalls: If a contaminated food product is identified, it may be recalled by the Food Standards Agency (FSA) to prevent further consumption. Public alerts may also be issued to inform the public of specific products or locations involved in an outbreak.

If symptoms are severe or prolonged (such as persistent vomiting, dehydration, high fever or blood in stool), contact a healthcare professional immediately, either by requesting an urgent appointment with your GP or by contacting 111. Certain groups, such as young children, elderly individuals, pregnant women and those with weakened immune systems, should be particularly cautious and seek medical help promptly.

Conclusion

Food safety is essential to safeguarding health and well-being. Through proper food handling, preparation and storage, we can greatly reduce the risk of foodborne illnesses and protect ourselves, our families and our communities from potentially serious infections. By following simple yet effective practices, such as maintaining good personal hygiene, cooking foods to safe temperatures, avoiding cross-contamination and keeping high-risk foods away from vulnerable groups, we can ensure that the food we consume is as safe as possible.

Staying vigilant about these practices is vital. Remembering to wash hands thoroughly, check food temperatures, store perishables correctly and clean utensils and surfaces after each use creates a safer environment and prevents the spread of pathogens. Incorporating these food safety practices into our daily routines is an easy step we can all take. Practising food safety in our homes, workplaces and communities contributes to healthier lives and a stronger public health framework.