Salmonella infections occur when you ingest one of the disease-causing strains of Salmonella. Exposure to Salmonella bacteria most commonly occurs through contact with contaminated foods, especially poultry, meat, eggs and egg products, and raw dairy products.

Salmonella can also be contracted via contact with other Salmonella reservoirs including dogs, cats, pigs, reptiles, rodents, cattle, and other infected people. An infected person or animal will often shed infectious bacteria in their feces. Any food product that has come into contact with animal feces — including fruits and vegetables — can spread Salmonella. Water can also be a source of Salmonella exposure. You need not swallow contaminated food or water to become infected: you can become infected by touching something that is contaminated with Salmonella and then touching your mouth. As few as six Salmonella bacteria can cause a severe Salmonella infection, far less than is visible to the naked eye.

Salmonella bacteria are quite hardy and can survive for months in water, ice, sewage, and frozen foods. However, while Salmonella can inhabit almost anything that humans consume, the bacteria are easily eliminated by thorough cooking.