Ingredient Driven Outbreaks: The Inside is Bigger than the Outside

The current Salmonella Typhimurium outbreak associated with a peanut processing plant in Blakely, Georgia, appears to have begun in September 2008, and was first detected in mid-November 2008 by DNA fingerprinting of Salmonella in public health labs across the country [last blog link]. The broad distribution of peanut butter and peanut paste shipped to food manufacturing companies from this single plant throughout the country has triggered the recall of nearly two hundred food products and exposed a critical factor supporting the continued emergency of food-borne outbreaks.

This outbreak represents a mix of our standard “product–driven” and “ingredient driven” outbreaks. The implicated product was first identified by excellent work from our Minnesota colleagues in mid-January who identified peanut butter distributed to institutions as a likely source and identified the outbreak strain in a King Nut peanut butter bucket. However, the peanut butter from institutions did not account for all the illnesses.

The associated “ingredient driven” aspect was uncovered with the recognition that peanut paste (and some of the peanut butter) from the processing plant was used as an ingredient in numerous peanut butter containing products, including cookies, crackers, ice cream, frozen meals, and dog treats. To clarify whether other peanut butter containing foods were associated with the outbreak, CDC, along with state partners, conducted an epidemiologic study. Preliminary analysis reveals an association between illness and consumption of pre-packaged peanut butter crackers, specifically with Austin and Keebler brands.

This outbreak is a timely example of how contamination in one place can work its way into many foods and lead to many illnesses across the country and is a harbinger of foodborne outbreaks for this century. These types of outbreaks bring two major challenges:

1. It is difficult to identify the source of the outbreak when the contaminant is in a wide range of foods, and
2. It is difficult to trace and recall the many foods affected and to provide easy/quick public guidance.

It also underscores the need to get much faster in detecting and responding to the outbreaks, including improving rapidly DNA fingerprinting Salmonella in state labs for critical early recognition, rapidly interviewing cases by state/local public health departments to provide vital clues to the source, and rapidly coordinating nationwide studies that can rapidly confirm the source.