Multistate Outbreak of Human Salmonella Montevideo Infections
Posted January 22, 2010
This outbreak appears to be over. However, Salmonella is an important cause of human illness in the United States. More information about Salmonella, and steps people can take to reduce their risk of infection, can be found on the CDC Salmonella Web Page.
CDC is collaborating with public health officials in many states, the U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS), and the U.S. Food and Drug Administration (FDA) to investigate a multistate outbreak of Salmonella serotype Montevideo infections. Investigators are using DNA analysis of Salmonella bacteria obtained through diagnostic testing to identify cases of illness that may be part of this outbreak.
Persons Infected with the Outbreak Strain of Salmonella Montevideo, United States, by State, as of 01/22/10 at 12:00 pm EST (n=184)
Infections with the outbreak strain of Salmonella Montevideo, by date of illness onset (n=184 for whom information was reported as of 01/22/10 at 12:00 pm EST)
As of 12:00 pm EST on January 22, 2010, a total of 184 individuals infected with a matching strain of Salmonella Montevideo have been reported from 38 states since July 1, 2009. The number of ill persons identified in each state with this strain is as follows: AL (2), AZ (5), CA (30), CO (2), CT (4), DE (2), FL (2), GA (3), IA (1), IL (11), IN (3), KS (3), LA (1), MA (12), MD (1), ME (1), MI (1), MN (4), NC (9), ND (1), NE (1), NH (1), NJ (7), NY (15), OH (9), OK (1), OR (8), PA (3), RI (2), SC (1), SD (3), TN (3), TX (7), UT (7), VA (1), WA (14), WV (1), and WY (2). Because this is a commonly occurring strain, public health investigators may determine that some of the illnesses are not part of this outbreak.
Among the persons with reported dates available, illnesses began between July 2, 2009 and January 1, 2010. Infected individuals range in age from <1 year old to 88 years old and the median age is 37 years. Fifty-two percent of patients are male. Among the 125 patients with available information, 35 (28%) were hospitalized. No deaths have been reported.
The outbreak can be visually described with a chart showing the number of persons who became ill each day. This chart is called an epidemic curve or epi curve. Illnesses that occurred after January 4, 2010 might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 3 weeks. Please see the Salmonella Outbreak Investigations: Timeline for Reporting Cases for more details.
Investigation of the Outbreak
A widely distributed contaminated food product might cause illnesses across the United States. The identity of the contaminated product often is not readily apparent. In outbreaks like this one, identification of the contaminated product requires conducting detailed standardized interviews with persons who were ill. It may also require conducting interviews with non-ill members of the public ("controls") to get information about foods recently eaten and other exposures to compare with information from the ill persons. The investigation is often supplemented by laboratory testing of suspected products. In addition, investigators sometimes use purchase information provided by ill persons to trace suspect products back to the point of production. This process is labor intensive and typically takes weeks. It is not always successful. As soon as a source of the outbreak is identified, if there is evidence of ongoing risk, public health officials advise the public to avoid the implicated product and recalls are conducted when appropriate. CDC and its public health partners are vigorously working to identify the specific contaminated product or products that are causing illnesses and will update the public on the progress of this investigation as information becomes available.
Clinical Features/Signs and Symptoms
Most persons infected with Salmonella develop diarrhea, fever, and abdominal cramps 12–72 hours after infection. Infection is usually diagnosed by culture of a stool sample. The illness usually lasts from 4 to 7 days. Although most people recover without treatment, severe infections may occur. Infants, elderly persons, and those with weakened 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.
More general information about Salmonella can be found here under Salmonella FAQs.