According to CDC, most people who are infected with salmonella bacteria develop diarrhea, fever and cramps, about 12 to 72 hours later.  (The Food & Drug administration reports the onset time as 6 to 48 hours later).  This illness is called Salmonellosis. 40,000 cases of Salmonella are reported each year in the United States.  Because many cases never get detected or reported, the Food and Drug Administration estimates that 2 to 4 million cases occur in the United States each year.

Salmonellosis can cause nausea, vomiting, abdominal cramps, diarrhea, fever and headache.

According to the Centers for Disease Control, most persons who are infected with Salmonella recover four to seven days later, without treatment. Sometimes, however, the diarrhea becomes severe, and the person may need to be hospitalized.  “In these patients, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites and can cause death unless the person is treated promptly with antibiotics,” CDC says. 

As with many illnesses, elderly people, infants, and people with impaired immune systems (from AIDS or cancer treatments, for example) are more likely to have a severe illness.

Most people recover completely from Salmonellosis, although it may be several months before their bowel habits are entirely normal.  A small number of people will go on to develop Reiter’s syndrome, which is characterized by pains in their joints, irritation of the eyes, and painful urination. The syndrome can last for months or years, and can lead to chronic arthritis which is difficult to treat.

Salmonella lives in the intestinal tracts of humans and animals, and is passed on to people who eat food contaminated with feces. 

CDC warns that people should be especially vigilant about washing their hands after handling reptiles, because reptiles are “particularly likely” to harbor Salmonella. 

Although the bacteria often is found in animal products, like beef, poultry, milk, and eggs, all food may become contaminated.  CDC has recently announced that it has uncovered an outbreak stemming from Peter Pan and Great Value peanut butter contaminated by Salmonella.

Since thorough cooking kills Salmonella, precooked, ready-to-eat foods should not be contaminated with Salmonella.

CDC’s website – information on Salmonella

FDA’s Bad Bug book – Salmonella entry

Wikipedia list of United States foodborne illness outbreaks

General Salmonella information, including research, by two professors from San Diego State University