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Multistate Outbreak of Salmonella Saintpaul Infections Linked to Raw Produce

Posted July 22, 2008

Click here to go to the Final Update

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.

 

Cases infected with the outbreak strain of Salmonella Saintpaul, United States, by state
Incidence of cases of infection with the outbreak strain of Salmonella Saintpaul, United States, by state
Interpretation of Epidemic Curves During an Active Outbreak

CDC is collaborating with public health officials in many states, the Indian Health Service, and the U.S. Food and Drug Administration (FDA) to investigate an ongoing multi-state outbreak of human Salmonella serotype Saintpaul infections. An initial epidemiologic investigation in New Mexico and Texas comparing foods eaten by persons who were ill in May to foods eaten by well persons identified consumption of raw tomatoes as strongly linked to illness. A similar but much larger, nationwide study comparing persons who were ill in June to well persons found that ill persons were more likely to have recently consumed raw tomatoes, fresh jalapeño peppers, and fresh cilantro. These items were commonly, though not always, consumed together, so that study could not determine which item(s) caused the illnesses. 

Recently, many clusters of illnesses have been identified in several states among persons who ate at restaurants. Most clusters involve fewer than 5 ill persons. Three larger clusters have been intensively investigated. In one, illnesses were linked to consumption of an item containing fresh tomatoes and fresh jalapeño peppers. In the other two, illnesses were linked to an item containing fresh jalapeño peppers and no other of the suspect items. Other clusters are under active investigation. The accumulated data from all investigations indicate that jalapeño peppers are likely to be a major cause of this outbreak. Fresh serrano peppers and fresh tomatoes remain under investigation. Investigators from many agencies are collaborating to track the source of the implicated peppers and other produce items.

An FDA laboratory detected Salmonella Saintpaul with the outbreak strain fingerprint pattern in a sample of jalapeño pepper obtained from a distribution center in McAllen, Texas. The distributor is working with FDA to recall the contaminated product in the United States. The peppers were grown in Mexico; investigators are working to determine where they were contaminated.

Since April, 1256 persons infected with Salmonella Saintpaul with the same genetic fingerprint have been identified in 43 states, the District of Columbia, and Canada. These were identified because clinical laboratories in all states send Salmonella strains from ill persons to their State public health laboratory for characterization. The number of ill persons identified in each state is as follows: Alabama (2 persons), Arkansas (19), Arizona (54), California (9), Colorado (16), Connecticut (5), Florida (3), Georgia (35), Idaho (6), Illinois (115), Indiana (18), Iowa (2), Kansas (19), Kentucky (2), Louisiana (1), Maine (1), Maryland (37), Massachusetts (28), Michigan (25), Minnesota (22), Mississippi (2), Missouri (20), Montana (1), New Hampshire (5), Nevada (12), New Jersey (14), New Mexico (103), New York (38), North Carolina (23), Ohio (10), Oklahoma (25), Oregon (11), Pennsylvania (12), Rhode Island (3), South Carolina (2), Tennessee (9), Texas (475), Utah (2), Virginia (31), Vermont (2), Washington (17), West Virginia (1), Wisconsin (13), and the District of Columbia (1). Five ill persons are reported from Canada; four appear to have been infected while traveling in the United States, and one illness remains under investigation.

Among the 1202 persons with information available, illnesses began between April 10 and July 5, 2008, including 20 who became ill on July 1 or later. These numbers include those with estimated onset dates as well as those with reported onset dates. Patients range in age from <1 to 99 years; 50% are female. The rate of illness is highest among persons 20 to 29 years old; the rate of illness is lowest in children 5 to 19 years old and in persons 80 or more years old. At least 231 persons were hospitalized. A man in his eighties who died in Texas from cardiopulmonary failure had an infection with the outbreak strain at the time of his death; the infection may have contributed to his death. A man in his sixties who died in Texas from cancer had an infection with the outbreak strain of at the time of his death; the infection may have contributed to his death.

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. Please see Interpretation of Epidemic Curves During an Active Outbreak. It shows that the number of persons who became ill peaked during May and decreased in June. The average number of persons who became ill between May 20 and June 10 was 33 per day. The average number of persons who became ill between June 11 and June 20 was 19 per day. The outbreak appears to be ongoing, but with fewer new illnesses reported each day. Illnesses that occurred recently may 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 2-3 weeks. Please see the Salmonella Outbreak Investigations: Timeline for Reporting Cases for more details regarding the 2-3 week time period.

Only 6 persons infected with this strain of Salmonella Saintpaul were identified in the country during April through June of 2007.  The previous rarity of this strain and the distribution of illnesses in all U.S. regions suggest that the implicated food is distributed throughout much of the country. Because many persons with Salmonella illness do not have a stool specimen tested, it is likely that many more illnesses have occurred than those reported. Some of these unreported illnesses may be in states that are not on today’s map.

Health officials have worked continuously since late May to investigate this outbreak. CDC has sent 29 people to the field to work with other public health officials. The investigation is complex and difficult. One difficult aspect is that people often have difficulty remembering exactly what foods they ate, and remembering specific ingredients in those foods is even more difficult. Although laboratory testing of foods might help identify the source, perishable foods that were consumed by ill persons are often not available to test. When food items are mixed together and consumed in the same dish, all the items may be statistically linked to illness. In that case, determining by statistical means which item caused the illness can be difficult or impossible. Tracing suspect produce items back to processors and growers is an integral part of the effort to identify a single source and a possible means of contamination.

Clinical features of Salmonella Infection

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 4-7 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. In these severe cases, antibiotic treatment may be necessary.

Advice to consumers

The contaminated peppers may still be in grocery stores, homes, and restaurants. Until more is known about the likely location of contamination, FDA is advising all persons to avoid consuming raw jalapeño peppers and dishes containing those raw peppers. Consumers should be aware that raw jalapeño peppers are often used in the preparation of fresh salsa, pico de gallo, guacamole, and other dishes. Cooked or pickled peppers from jars and cans are not part of this warning.

Persons with increased risk of severe infection, including infants, elderly persons, and those with impaired immune systems, should also not consume raw serrano peppers. Other persons who want to reduce their risk of Salmonella infection can take similar precautions.

FDA has indicated that tomatoes on the market today are safe to consume.

Consumers everywhere are advised to follow the general food safety guidelines below:

  • Refrigerate within 2 hours or discard cut, peeled, or cooked produce items
  • Avoid purchasing bruised or damaged produce items, and discard any that appear spoiled.
  • Thoroughly wash all produce items under running water.
  • Keep produce items that will be consumed raw separate from raw meats, raw seafood, and raw produce items.
  • Wash cutting boards, dishes, utensils, and counter tops with hot water and soap when switching between types of food products.

Consumers are reminded that vegetables are an important part of a healthy diet and that cooking vegetables kills bacteria, including Salmonella.

FDA information on this investigation.

More information about Salmonella and this investigation can be found at:

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