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The symptoms of Salmonella food poisoning are fever, abdominal cramps, vomiting and diarrhoea. Free GCSE Edexcel Biology notes and 13 questions answered.
Food Poisoning - Salmonella Infection is part of Communicable diseases in GCSE Edexcel Higher Biology.
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The symptoms of Salmonella food poisoning are fever, abdominal cramps, vomiting and diarrhoea. Free GCSE Edexcel Biology notes and 13 questions answered.
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Use this lesson to stay inside Communicable diseases while connecting the detail back to the wider Topic 5: Health, disease and the development of medicines topic.
Read the core explanations from Food Poisoning - Salmonella Infection before testing yourself from memory.
You've probably heard warnings about undercooked chicken or leaving food out too long. Behind these warnings lurks a microscopic enemy: Salmonella bacteria. These pathogens don't just make you feel unwell - they launch a coordinated attack on your digestive system that can leave you bedridden for days.
Trap: Many students think food poisoning is caused by 'bad food going off'. Actually, fresh-looking food can harbour millions of dangerous bacteria. Salmonella doesn't change the taste, smell, or appearance of food - making it particularly dangerous.
Salmonella has several cunning ways to reach your digestive system. Understanding these transmission routes is crucial for both prevention and exam success.
Primary transmission route: Ingestion of bacteria in contaminated food. This happens when Salmonella bacteria are present in raw ingredients (especially poultry, eggs, and dairy) or when bacteria transfer to food during preparation.
Secondary transmission route: Cross-contamination during food preparation in unhygienic conditions. Picture a kitchen where raw chicken is chopped on a board, then vegetables are cut on the same unwashed surface. The bacteria transfer from the contaminated surface to the 'safe' vegetables.
Worked example: Worked Example: Applying Food Poisoning - Salmonella Infection
Use this method to answer an exam-style question about what is salmonella food poisoning?.
Answer: A complete response links mechanism, evidence, and conclusion for food poisoning - salmonella infection.
Once Salmonella bacteria reach your intestines, they don't just sit there - they actively attack your body through two mechanisms. This dual assault explains why food poisoning symptoms are so severe.
Mechanism 1: Bacterial invasion - The bacteria multiply rapidly in your intestines, damaging the intestinal lining and triggering your immune system's inflammatory response.
Mechanism 2: Toxin production - As the bacteria multiply, they secrete poisonous toxins that further damage your intestinal cells and disrupt normal digestive processes.
The classic symptoms of Salmonella food poisoning result from this bacterial assault:
Fever: Your body raises its temperature to fight the infectionAbdominal cramps: Intestinal muscles contract painfully as they try to expel the bacteriaVomiting: Your stomach attempts to reject contaminated contentsDiarrhoea: Your intestines flush out bacteria and toxins with excess water
The UK has implemented a highly successful strategy to control Salmonella transmission: vaccinating poultry against the bacteria. This approach targets the problem at its source rather than just treating symptoms.
Why poultry? Chickens and other poultry are natural reservoirs for Salmonella bacteria. The bacteria can live harmlessly in their intestines but contaminate eggs and meat during production.
How vaccination works: Vaccinated birds develop immunity to Salmonella, preventing the bacteria from establishing infections in poultry flocks. This dramatically reduces bacterial contamination of eggs and meat entering the food chain.
Population-level impact: When most birds in a population are vaccinated, it creates 'herd immunity' - even unvaccinated birds are protected because there are fewer sources of infection.
Salmonella questions appear frequently in GCSE papers, often testing your understanding of transmission, symptoms, and prevention. Here's how to tackle them with confidence.
Common exam mistakes to avoid:
Mistake 1: Writing 'Salmonella is a virus' - it's a bacteriumMistake 2: Saying symptoms are caused only by bacteria OR only by toxins - it's bothMistake 3: Claiming vaccination kills bacteria in food - it prevents infection in animalsMistake 4: Forgetting that cross-contamination during preparation is a major transmission route
Published by Revise Right. Use the official specification reference to check the requirements for your course. Content updated: 2026-03-23.
Move to the related lessons or back to the topic page when you need the wider sequence before exam-style practice.
The symptoms of Salmonella food poisoning are fever, abdominal cramps, vomiting and diarrhoea. They are caused both by the bacteria damaging the intestinal lining and by the toxins the bacteria secrete as they multiply.
Salmonella food poisoning is an infection caused by Salmonella bacteria ingested through contaminated food or food prepared under unhygienic conditions. The bacteria multiply in the intestines and secrete toxins that cause severe gastrointestinal symptoms.
Cross-contamination is when bacteria transfer from a contaminated surface to other food during preparation in unhygienic conditions. For example, chopping raw chicken on a board and then using the same unwashed surface for vegetables can spread Salmonella.
Salmonella is spread mainly by eating contaminated food, especially raw poultry, eggs and dairy. It also spreads through cross-contamination during food preparation in unhygienic conditions, such as when vegetables are cut on the same unwashed board as raw chicken.
Bacterial toxins are poisonous chemical substances produced and secreted by pathogenic bacteria that damage host cells and cause disease symptoms. Salmonella secretes toxins as it multiplies in the intestines.
Poultry in the UK are vaccinated against Salmonella because chickens are natural reservoirs for the bacteria, which can contaminate eggs and meat. Vaccinated birds develop immunity, which dramatically reduces bacterial contamination of eggs and meat entering the food chain.
Salmonella is a bacterium, not a virus. Salmonella bacteria cause disease by multiplying in the intestines and secreting poisonous toxins, which are chemical substances that damage host cells and cause disease symptoms.
Salmonella is especially found in raw poultry, eggs and dairy. Chickens and other poultry are natural reservoirs for Salmonella, which can live harmlessly in their intestines but contaminate eggs and meat during production.
Salmonella does not change the taste, smell or appearance of food, so contaminated food can look fresh and safe. Fresh-looking food can harbour millions of dangerous bacteria, which makes Salmonella particularly dangerous.
Salmonella causes diarrhoea because the intestines flush out bacteria and toxins with excess water, and vomiting because the stomach attempts to reject contaminated contents. Abdominal cramps happen as intestinal muscles contract to expel the bacteria.
Salmonella causes disease in two ways: the bacteria multiply rapidly in the intestines, damaging the intestinal lining, and they secrete toxins that further damage intestinal cells. Symptoms are caused by both the bacteria and the toxins.
Vaccinating most chickens in a population creates herd immunity, so even unvaccinated birds are protected because there are fewer sources of infection. This dramatically reduces Salmonella contamination of eggs and meat entering the food chain.
Vaccinating chickens does not kill Salmonella in food; it prevents infection in the animals. Vaccinated birds develop immunity, so the bacteria cannot establish infections in poultry flocks and fewer eggs and meat are contaminated.