Salmonella is a bacterium that sometimes turns up in the food supply, including chicken, tomatoes, peanuts, and even pet food. It is found worldwide in both cold-blooded and warm-blooded animals, and in the environment. Salmonella bacteria grow in the intestinal tracts of animals and humans and can cause food poisoning. Illnesses range from nonviolence to very serious infections that can kill people who have low immune system. It can be transferred between humans and other animals. Many infections are due to ingestion of contaminated food.