Salmonella infections are among the most common foodborne illnesses. This type of bacterial infection occurs most often from the ingestion of contaminated food or water.

Any type of food can become contaminated with the salmonella bacteria. The foods that most frequently transmit salmonella are poultry, meat, eggs and dairy products. Contamination can occur in a variety of ways – including exposure to bacteria during slaughter, processing, distribution or food preparation. Most contaminated foods appear (and smell) normal.

People may also be exposed to salmonella through contact with household pets, especially reptiles (e.g., lizards, turtles, snakes). Most reptiles in the United States have salmonella. If an infected reptile’s skin has been contaminated by its feces, handling the pet can transfer bacteria and lead to a salmonella infection.

There are two types of salmonella infection, with the most common causing signs and symptoms such as nausea, abdominal pain, diarrhea and vomiting. Symptoms usually occur anywhere between 12 and 72 hours after ingestion of the contaminated product. Some people may carry salmonella in their bodies for more than a year without developing symptoms. These people are known as carriers because of their ability to infect others. 

Much rarer is a type of salmonella that can cause a set of severe symptoms called enteric fever. Symptoms of enteric fever include diarrhea accompanied by a rash on the abdomen or chest. This type of salmonella infection usually only occurs among people who have traveled in developing nations.

Diagnosis of salmonella infection begins with a physical examination, which includes a medical history and a list of foods recently consumed. Fecal tests or blood tests can identify the presence of salmonella.

The very young, very old and people with compromised immune systems have a greater risk of developing salmonella infection after exposure to the bacteria than the general population. In addition, decreased levels of stomach acid and impaired intestinal functioning can make a person more likely to develop a salmonella infection.

Most cases of salmonella infection resolve without treatment within a week. For the duration of an infection, it is recommended that patients drink plenty of fluids (to avoid dehydration that can occur as the result of severe diarrhea) and consume a bland, easy-to-digest diet (to avoid aggravating any nausea). Severe cases of salmonella infection may require hospitalization and administration of intravenous (I.V.) fluids.

Antibiotics are not typically used to treat salmonella infections, since salmonella does not usually respond to antibiotics and the medication may delay expulsion of the bacteria from the body. However, antibiotics may be used in cases of enteric fever, or when infection travels outside the intestines via the bloodstream. Patients who are deemed likely to have more severe infection and a high risk of complications as a result of infection (e.g., infants, the elderly, individuals with immune system deficiencies) may also be treated with antibiotics.

Freezing foods contaminated with salmonella hinders the growth of the bacteria, but will not destroy it. Salmonella bacteria can only be destroyed by thorough cooking. Thus, salmonella infection can be prevented in a variety of ways. Foods such as raw meat, poultry, eggs and unpasteurized milk should be stored in the freezer or the coldest parts of the refrigerator. Washing hands before and after food preparation, using separate cutting boards for meat and vegetables and thoroughly cooking meat, poultry and eggs may also prevent salmonella infection.