CausesBy Mayo Clinic staff
Salmonella bacteria live in the intestines of people, animals and birds. Most people are infected with salmonella by eating foods that have been contaminated by feces. Commonly infected foods include:
- Raw meat, poultry and seafood. Feces may get onto raw meat and poultry during the butchering process. Seafood may be contaminated if harvested from contaminated water.
- Raw eggs. While an egg's shell may seem to be a perfect barrier to contamination, some infected chickens produce eggs that contain salmonella before the shell is even formed. Raw eggs are used in homemade versions of mayonnaise and hollandaise sauce.
- Fruits and vegetables. Some fresh produce, particularly imported varieties, may be hydrated in the field or washed during processing with water contaminated with salmonella. Contamination also can occur in the kitchen, when juices from raw meat and poultry come into contact with uncooked foods, such as salads.
Many foods become contaminated when prepared by people who don't wash their hands thoroughly after using the toilet or changing a diaper. Infection also can occur if you touch something that is contaminated, including pets, especially birds and reptiles, then put your fingers in your mouth.
Food handlers who return to work before the infection completely clears up can continue to spread the disease. Some people who get salmonella infection become chronic carriers, meaning they continue to excrete the bacteria in their feces or, rarely, urine for a year or more after their signs and symptoms clear up. Some carriers can pass Salmonella infection without having signs or symptoms of the disease.
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