Salmonellosis is an infection caused by the Salmonella bacteria. Persons infected with Salmonella may develop diarrhea, fever, and abdominal cramps 12 to 72 hours after becoming infected. The illness usually lasts 4 to 7 days, and most persons recover without treatment. However, in some persons the diarrhea may be so severe that the patient needs 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. The elderly, infants, and those with impaired immune systems are more likely to have a severe illness.