CDC is collaborating with public health officials in many states, the United States Department of Agriculture (USDA) – Food Safety and Inspection Service (FSIS), and the U.S. Food and Drug Administration (FDA) to investigate an ongoing multistate outbreak of human infections due to Salmonella serotype Typhimurium.

As of Wednesday, January 7, 2009, 388 persons infected with the outbreak strains of Salmonella Typhimurium have been reported from 42 states. Among the 372 persons with dates available, illnesses began between September 3 and December 29, 2008, with most illnesses beginning after October 1, 2008. Patients range in age from <1 to 103 years; 48% are female. Among persons with available information,18% were hospitalized.

CDC and its public health partners are vigorously working to identify the specific contaminated product, probably a food or foods, that is causing this outbreak. Outbreaks from a widely distributed contaminated product may cause illnesses across the United States, and the identity of the contaminated product is often not readily apparent.

In outbreaks like this one, identification of the contaminated product requires conducting detailed standardized interviews with persons who were ill and with non-ill members of the public ("controls") to compare foods they recently ate and other exposures. Using statistical methods, the contaminated item is identified as one to which significantly more ill persons than controls were exposed. This statistically-based method of identifying contaminated products is often supplemented by laboratory testing of suspect products. The investigation is labor intensive and typically takes weeks. It is not always successful. As soon as a source is identified, if there is evidence of ongoing risk, public health officials advise the public to avoid it, and conduct recalls when appropriate.
Clinical features

Most persons infected with Salmonella develop diarrhea, fever, and abdominal cramps 12 to 72 hours after infection. Infection is usually diagnosed by culture of a stool sample. The illness usually lasts 4 to 7 days. Although most people recover without treatment, severe infections may occur. Infants, elderly persons, and those with impaired immune systems are more likely than others to develop severe illness. When severe infection occurs, Salmonella may spread from the intestines to the bloodstream and then to other body sites and can cause death unless the person is treated promptly with antibiotics.