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CDC: Fast Work and Strong Epidemiological Evidence Led to Source of E. Coli Outbreak

ground beefThe U.S. Centers for Disease Control and Prevention (CDC) is praising state health officials and other collaborators for their work in identifying ground beef from the Wolverine Packing Company as the source of a multi-state E. coli O157:H7 outbreak.

“A lot of the footwork was done in the state health departments,” Dr. Robert Tauxe, Deputy Director of CDC’s Division of Foodborne Waterborne, and Environmental Diseases, told Food Safety News.

After the Michigan and Ohio health departments informed CDC that they had a small number of E. coli cases with matching DNA “fingerprints” in the two states, state officials began interviewing patients and CDC informed the Department of Agriculture’s Food Safety and Inspection Service (FSIS).

“When the interviews of the patients started turning up that they all reported eating ground beef — usually in restaurants and often undercooked — FSIS really switched into high gear and started tracing that back from restaurants to see if there was something in common,” Tauxe explained.

Although testing of the suspect meat came back negative for E. coli O157, the evidence from epidemiologic and traceback investigations indicated that Wolverine Packing was the likely source.

“This isn’t like the frozen meat that’s left over in somebody’s home — exactly the same lot,” Tauxe said. “Restaurants turn over their meat pretty quick. The meat that’s being sampled now may not even be the same meat.”

On May 19, the Detroit company recalled 1.8 million pounds of ground beef, which was shipped to distributors for retail and restaurant use nationwide.

“While none of the Wolverine Packing product has tested positive for the pathogen implicated in this outbreak, the company felt it was prudent to take this voluntary recall action in response to the illnesses and initial outbreak investigation findings,” said Wolverine spokesperson Chuck Sanger in a statement to the media.

Tauxe said that prompting a recall 10 days after first detection is “pretty good, especially because it looks like the product went to a lot of different states and so recalling that may have prevented a much bigger outbreak.”

CDC reports that 11 people in Michigan, Ohio, Massachusetts and Missouri have been infected with the E. coli strain. They range in age from 19 to 46 years, they became ill with symptoms between April 22 and May 2, and, of the 10 people with available information, six reported being hospitalized.

None of those sickened in this outbreak have developed a type of kidney failure called hemolytic uremic syndrome (HUS), and no deaths have been reported.

CDC officials do not believe that recent reports of an illness cluster in Kansas are connected with this E. coli outbreak because the DNA “fingerprints” of the bacteria obtained through pulsed-field gel electrophoresis, or PFGE, don’t appear to match.

“We’ll certainly still keep in touch with Kansas and continue to follow that cluster itself, but it doesn’t at this point look like there’s a connection to this investigation,” said Dr. Matthew Wise, lead for CDC’s foodborne outbreak response team.

“In any outbreak investigation, we always prospectively monitor PulseNet for E. coli that match that DNA fingerprint from all states,” he added. CDC hasn’t noticed any others yet.

That doesn’t mean the end of the story, though. Initially, it looked like the meat had only gone to the four states where there were cases of illness. That’s what the traceback found, but Tauxe said that FSIS is still working on the “trace forward” — identifying where all the meat ground in a certain day or at a certain plant went.

A note on the FSIS recall notice states, “Upon further investigation, FSIS now believes the product was sent to distribution centers nationwide.”

“It’s more than those four states, it’s a number of different places, it’s a number of different restaurants at least, but that’s still in progress, so we’re on the alert,” Tauxe said.

CDC is also using the situation to remind consumers not to rely on color to tell if meat is fully cooked, but rather use a thermometer to ensure it reaches an internal temperature of 160 degrees F.

A recent FSIS campaign compiled the research showing that color and texture are not reliable indicators of doneness and provided an extensive list of advice for cooking ground beef at home.

Since the meat from Wolverine packing was primarily intended for use in restaurants, CDC wants to empower consumers to ask restaurants to use a thermometer.

FSIS suggests: “When eating out, ask your server if ground beef patties have been cooked to at least 155 °F for 15 seconds (as recommended by the U.S. Food and Drug Administration Food Code), which is a safe option for restaurants or food service operations.”

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