Cross-contamination can occur, for example, if you prepare raw chicken on a chopping board and don't wash the board before preparing food that won't be cooked (such as salad), as the harmful bacteria can be spread from the chopping board to the salad. Show It can also occur if raw meat is stored above ready-to-eat meals and juices from the meat drip on to the food below. See preventing food poisoning for information about reducing these risks Types of infectionFood contamination is usually caused by bacteria, but it can also sometimes be caused by viruses or parasites. Some of the main sources of contamination are described below. CampylobacterIn the UK, campylobacter bacteria are the most common cause of food poisoning. The bacteria are usually found on raw or undercooked meat (particularly poultry), unpasteurised milk and untreated water. The incubation period (the time between eating contaminated food and the start of symptoms) for food poisoning caused by campylobacter is usually between two and five days. The symptoms usually last less than a week. SalmonellaSalmonella bacteria are often found in raw or undercooked meat, raw eggs, milk, and other dairy products. The incubation period is usually between 12 and 72 hours. The symptoms usually last around four to seven days. ListeriaListeria bacteria may be found in a range of chilled, "ready-to-eat" foods, including pre-packed sandwiches, cooked sliced meats and pâté, and soft cheeses (such as Brie or Camembert). All of these foods should be eaten by their "use-by" dates. This is particularly important for pregnant women, because a listeria infection (known as listeriosis) in pregnancy can cause pregnancy and birth complications, and can result in miscarriage. The incubation period can vary considerably, from a few days to several weeks. The symptoms will usually pass within three days. Escherichia coli (E. coli)Escherichia coli, often known as E. coli, are bacteria found in the digestive systems of many animals, including humans. Most strains are harmless but some can cause serious illness. Most cases of E. coli food poisoning occur after eating undercooked beef (particularly mince, burgers and meatballs) or drinking unpasteurised milk. The incubation period for food poisoning caused by E. coli is typically one to eight days. The symptoms usually last for a few days or weeks. ShigellaShigella bacteria can contaminate any food that has been washed in contaminated water. Symptoms typically develop within seven days of eating contaminated food and last for up to a week. An infection caused by Shigella bacteria is known as bacillary dysentery or shigellosis. See the topic on dysentery for more information about it. VirusesThe virus that most commonly causes diarrhoea and vomiting is the norovirus. It's easily spread from person to person, through contaminated food or water. Raw shellfish, particularly oysters, can also be a source of infection. The incubation period typically lasts 24-48 hours and the symptoms usually pass in a couple of days. In young children, the rotavirus is a common cause of infection from contaminated food. The symptoms usually develop within a week and pass in around five to seven days. ParasitesIn the UK, food poisoning caused by parasites is rare. It's much more common in the developing world. Parasitic infections that can be spread in contaminated food include:
The symptoms of food poisoning caused by a parasite usually develop within 10 days of eating contaminated food, although sometimes it may be weeks before you feel unwell. Salmonella infection (also known as salmonellosis) is an infection of the digestive tract (or gut), caused by Salmonella bacteria. There are thousands of Salmonella types and they are found in many domestic and wild animals. How do you get Salmonella infection? Salmonella bacteria can infect both people and animals, and can also grow in food and the environment. You become infected with Salmonella by ingesting the bacteria through your mouth. This can be by:
Person-to-person spread can happen if you come into contact with microscopic amounts of faeces (poo) from an ill person. Such spread may occur directly by close personal contact, or indirectly by touching contaminated surfaces such as taps, toilet flush buttons, toys and nappies. What are the signs and symptoms? Symptoms usually start between 6 hours to 7 days (usually 1 to 3 days) after you have ingested the bacteria and typically last for between 2 to 7 days. Symptoms can include:
Salmonella typhi and Salmonella paratyphi are certain types of Salmonella bacteria that cause typhoid and paratyphoid fever, which affect the whole body, not just the digestive tract. How do you know if you have it? There are many causes of gastroenteritis, and laboratory testing of a faecal specimen is necessary to confirm that symptoms are due to Salmonella infection. People with confirmed or suspected Salmonella infection should:
People with typhoid or paratyphoid fever will require antibiotic treatment. If you experience severe or prolonged symptoms you should visit a doctor. What should you do if you have the infection?
When travellingWhen travelling to developing countries, especially in Asia, the Pacific islands, Africa, the Middle East and Central and South America, you should avoid:
Fruit that you peel yourself is usually safe. Remember – ‘cook it, boil it, peel it, or leave it’. Use bottled water or disinfect water (by boiling, chemical treatment or purifiers) for drinking and brushing teeth. Read more about healthy international travel. Is there a vaccine for Salmonella?There are no vaccines that protect against most types of Salmonella. However, a typhoid vaccine is available for overseas travellers and can provide some protection. See your doctor or travel medicine specialist at least 2 months prior to departure to see if any vaccinations or medications are recommended. Where to get helpRemember
View and download this information as a PDF factsheet (300KB). Acknowledgements Public Health This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions. How long does it take for Salmonella poisoning to go away?Most people recover from Salmonella infection within four to seven days without antibiotics. People who are sick with a Salmonella infection should drink extra fluids as long as diarrhea lasts. Antibiotic treatment is recommended for: People with severe illness.
What is the fastest way to cure Salmonella?Most people recover without specific treatment. Antibiotics are typically used only to treat people with severe illness. Patients should drink extra fluids as long as diarrhea lasts. In some cases, diarrhea may be so severe that the person needs to be hospitalized.
What kills Salmonella stomach?Except after a meal, when the stomach is full of food, the pH of the normal human stomach can be very low, around pH 2, which will kill Salmonella and many other bacteria that cause enteric diseases.
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