Second Salmonella outbreak linked to tomatoes

Editor's note: The Salmonella serotype involved in this outbreak was incorrectly listed as Norfolk in this story when first published.

Dec 1, 2006 (CIDRAP News) – Federal officials are investigating a second Salmonella outbreak linked to restaurant tomatoes that occurred over the summer and early fall, sickening 106 people in 19 states.

The outbreak, first reported Nov 28 in the Produce News, involves restaurant tomatoes contaminated with Salmonella enterica serotype Newport.

The organism typically causes fever and nonbloody diarrhea that resolves in a week.

The S Newport outbreak marks the second Salmonella outbreak in tomatoes this fall. In early November, the CDC confirmed that an outbreak of Salmonella enterica serotype Typhimurium, which sickened 183 Americans in 21 states, plus two Canadians, was linked to restaurant tomatoes.

Christine Olson, MD, MPH, an epidemiology intelligence service officer with the enteric diseases epidemiology branch of the Centers for Disease Control and Prevention (CDC), told CIDRAP News that the outbreak was detected by PulseNet, an electronic network for sharing molecular fingerprinting (pulsed-field gel electrophoresis) data. She said the outbreak began in June and appears to have ended in October. She said the bulk of cases occurred in August and September; 15 cases were reported in October.

A case-control study the CDC launched in response to the S Newport outbreak revealed that about 35% to 40% of patients were hospitalized, she said.

Most of the S Newport cases occurred on the East Coast, Olson said. Pennsylvania, with 20 cases, had the highest number of illnesses. Though the S Newport outbreak geographically overlaps the S Typhimurium outbreak somewhat, she said the CDC wasn't aware of any people who were coinfected with both strains.

Olson said S Newport as been associated with tomatoes before. "We're trying to determine how best to prevent this type of contamination in produce," she noted. A multidrug resistant strain of S Newport has been responsible for cases of ground beef contamination in recent years.

The US Food and Drug Administration is working on a traceback investigation to determine the source of the S Newport contamination, Olson said.

See also:

CIDRAP overview of salmonellosis
http://www.cidrap.umn.edu/cidrap/content/fs/food-disease/causes/salmoview.html

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