Jalapeno, serrano peppers linked to 2008 salmonella outbreak

Barton Behravesh C. N Engl J Med. 2011;364:918-927.

Issue: April 2011

New findings from the 2008 Saintpaul serotype of Salmonella enterica outbreak indicate that jalapeno and serrano peppers were associated with transmission of foodborne disease and highlight challenges in epidemiologic identification, trace-back issues and the need for improvements in product-tracking for the prevention of raw-produce contamination in the US.

Earlier findings identified raw tomatoes as a cause of the outbreak; jalapeno and serrano peppers were subsequently identified as sources.

“Physicians should consider foodborne illness as a differential when patients visit their offices with acute gastrointestinal illness because their patient’s illness might be caused by a contaminant. They should submit their patients’ stool specimens for testing when appropriate,” Casey Barton Behravesh, DVM, DrPH, of theOutbreak Response and Prevention Branch of the CDC, told Infectious Disease News.

“Since this outbreak, CDC in collaboration with the US Department of Agriculture Food Safety and Inspection Service and the Association of Public Health Laboratories have invested in improving our capacity and methods to investigate foodborne disease outbreaks through the Outbreak Sentinel Sites project,” he said.

As previously reported in Infectious Disease News, there were more than 1,300 people infected with Saintpaul serotype of S. enterica between April and July 2008, with the same genetic fingerprint identified in the US (in 43 states and the District of Columbia) and Canada. Epidemiological studies comparing ill patients with healthy people in the affected areas found that ill patients were more likely to have recently consumed raw tomatoes, fresh jalapeno peppers and fresh cilantro. Because the items were commonly consumed together, the study could not determine which item or items caused the illnesses.

For this reason, Behravesh and colleagues conducted epidemiologic, trace-back and environmental studies of the outbreak. They defined a diarrhea case in a patient with laboratory-confirmed infection with the outbreak strain of Saintpaul serotype of S. enterica. Of the 1,500 cases, 21% were hospitalized and two patients died.

Of cases not associated with restaurant clusters, illness was associated with eating raw tomatoes (OR=5.6; 95% CI, 1.6-30.3); eating at a Mexican-style restaurant (OR=4.6; 95% CI, 2.1 to infinity); and consuming pico de gallo salsa (OR=4; 95% CI, 1.5-17.8), corn tortillas (OR=2.3; 95% CI, 1.2-5), salsa (OR=2.1; 95% CI, 1.1-3.9) and having raw jalapeno peppers in the household (OR=2.9; 95% CI, 1.2-7.6).

Jalapeno peppers and tomatoes were associated with three clusters with associated ingredients. Further, Saintpaul serotype of S. enterica was identified in jalapeno peppers from Texas and in serrano peppers on a farm in Mexico, according to the report. A source was not identified for the contaminated tomatoes.

“This outbreak highlights the recurring problem of outbreaks associated with fresh produce, as well as the importance of taking measures to reduce the contamination of produce wherever it might occur,” Barton Behravesh said. “Also, these investigations shed additional light on the potential risks associated with foods, like fresh salsas, that contain raw produce. Patients should know that foodborne pathogens, like salmonella, can make someone sick up to 1 week after eating contaminated food.”

Disclosure: Dr. Barton Behravesh reports no relevant financial disclosures.

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