Investigating the Salmonella Tennesse Outbreak Linked to Peanut Butter
An article in today’s issue of the CDC’s Morbidity and Mortality Weekly Report addresses the recent nationwide outbreak of Salmonella Tennessee linked to Peter Pan and Great Value peanut butters. The article explains the detection and investigation of the outbreak, which involved local, state, and federal health officials.
Here is a summary and explanation of the article:
- The investigation of the outbreak began in November 2006, when public health officials in PulseNet (the molecular subtyping network for foodborne disease surveillance) noted a substantial increase in the number of Salmonella Tennessee isolates—from 1-5 per month to 30 in October of 2006. When someone is diagnosed with a Salmonella infection (salmonellosis), an isolate of the Salmonella bacteria is tested to determine the serotype of Salmonella involved (approximately 2,500 Salmonella serotypes can cause salmonellosis). In this outbreak the serotype of Salmonella involved was Salmonella Tennessee.
- The CDC determined that three (3) closely-related pulsed-field gel electrophoresis (PFGE) patterns of Salmonella Tennessee were associated with this outbreak. PFGE patterns are “genetic fingerprints” of bacteria.
- For the CDC to consider a case of salmonellosis to be part of this outbreak, the Salmonella that sickened the individual had to be Salmonella Tennessee with a PFGE pattern matching one of the three outbreak patterns. Furthermore, the person had to be residing in the United States with symptom onset on or after August 1, 2006 (or, if onset date unknown, Salmonella Tennessee isolated on or after August 1, 2006). From a legal standpoint, the best cases against ConAgra, the maker of Peter Pan and Great Value peanut butters, are those that involve a Salmonella Tennessee case that the CDC recognizes as part of the outbreak. This is called a CDC-confirmed case of Salmonella Tennessee.
- As of May 22, 2007, a total of 628 persons infected with one of the 3 outbreak strains of Salmonella serotype Tennessee had been reported from 47 states since August 1, 2006.
- To determine the source of the outbreak, epidemiologists interviewed patients with the outbreak strain of Salmonella Tennessee to determine what they had eaten before they got sick. They also interviewed a control group of people who had never been sickened by Salmonella Tennessee.
Patients were more likely than controls to have eaten peanut butter (81% versus 65%, matched odds ratio [mOR] = 1.9, 95% confidence interval [CI] = 0.8--5.2), to have eaten peanut butter more than once a week (66% versus 40%, mOR = 3.5, CI = 1.4--9.9), and to have eaten either Peter Pan or Great Value peanut butter (67% versus 13%, mOR = 10.9, CI = 3.8--43.0). Neither the consumption of other peanut butter brands nor consumption of turkey products (another suspected source of the outbreak) was associated with illness.
- On February 14, 2007, the FDA issued a health alert to consumers indicating that they should not eat Peter Pan or Great Value peanut butter with a product code beginning with 2111, and ConAgra issued a recall of this peanut butter. All of the recalled peanut butter was manufactured in a single facility in Georgia operated by ConAgra Foods.
- New case reports of one of the three outbreak patterns of Salmonella Tennessee decreased substantially after the February 14 recall.
- After the recall, the CDC and state public health laboratories tested leftover peanut butter from patients sickened by one of the outbreak patterns of Salmonella Tennessee. These tests found 21 jars of peanut butter contaminated with Salmonella Tennessee with a PFGE pattern matching one of the outbreak strains. The production dates for these 21 jars ranged from July 2006 to December 2006. The FDA isolated Salmonella Tennessee from 13 unopened jars of Peter Pan and Great Value peanut butter with production dates ranging from August 2006 to January 2007 and from two plant environmental samples.
- According to the CDC:
This is the first reported outbreak of a foodborne illness caused by peanut butter consumption in the United States. . . Peanuts can become contaminated with salmonellae during growth, harvest, or storage, and the organisms are able to survive high temperatures in a high-fat, low-water--activity environment . Peanut butter provides such an environment, and although it typically undergoes heat treatment to temperatures >158°F (>70°C), such heating might not always eliminate salmonellae. In addition, after heat treatment, peanut butter that is being processed might be contaminated by salmonellae that are introduced into the production environment on raw peanuts or another source (e.g., animals in the production plant, salmonellae brought into the plant on containers or humans from the outside environment, or other ingredients used to make peanut butter).
The article discussed above, “Multistate Outbreak of Salmonella Serotype Tennessee Infections Associated with Peanut Butter --- United States, 2006—2007,” can be found in the June 1, 2007, issue of the Morbidity and Mortality Weekly Report (MMWR).
Our firm, a leading foodborne illness litigation law firm, is currently representing victims of the Salmonella Tennessee outbreak linked to Peter Pan and Great Value peanut butters. To contact the firm, please call toll-free at 1-888-377-8900 or submit the firm's online consultation form.
