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Fast Response May Limit Scope of Listeria Outbreak Linked to Cheese Sold Nationwide

The rapid detective work that linked a four-state Listeria outbreak — which has killed one person, caused a miscarriage, and hospitalized four others –- to cheese sold nationwide could prevent many illnesses, according to health officials.

Dr. Barbara Mahon, deputy chief of the Enteric Diseases Epidemiology Branch at the Centers for Disease Control and Prevention, told Food Safety News that Minnesota state health officials played a critical role by quickly detecting a cluster of illnesses. According to Dr. Mahon, the total number of Listeria cases reported to PulseNet, CDC’s national foodborne illness surveillance system, did not rise above normal during the outbreak. Minnesota began an active investigation into two local cases and soon realized there were cases reported in Illinois, Indiana and Ohio that matched the cluster.

Once Minnesota contacted CDC, it took just six days to identify the likely cause of the outbreak as Crave Brothers Les Frères cheeses and to take action with a CDC announcement and a nationwide recall. This was a significantly shorter timeline than the average Listeria outbreak investigation, according to Mahon.

“Listeria outbreaks can be slow moving and they can continue for a time even after contaminated food is removed from the market,” she said. “We’re very pleased with how well this came together to get product off of shelves as quickly as possible.”

CDC does expect more cases will be reported and added to the outbreak, but the official count still stands at five cases in four states. That number includes one reported death of an elderly person in Minnesota and four other hospitalizations, including one woman who suffered a miscarriage.

Mary Choi, a spokeswoman for the Minnesota Department of Health, said pinpointing the likely cause of the outbreak was “a collaborative effort” between CDC, the U.S. Food and Drug Administration, the Minnesota Department of Agriculture, and the foodborne epidemiologists from Illinois, Indiana, and Ohio.

Choi said testing done by the Minnesota Department of Agriculture found the outbreak strain of Listeria in two samples of Crave Brothers cheese products purchased from two separate retail locations in Minnesota.

The soft cheeses in question were sold by Whole Foods in 33 states and the District of Columbia and by Kroger in 20-some states. Dillons, Baker’s, Fred Meyer, Ralphs, QFC and Gerbes retailers also sold the recalled cheese. FDA’s food recall section has a full description of all of the cheeses recalled. Three types of cheese are involved: Les Frères, Petit Frère, and Petit Frère with Truffles cheeses — all made by Crave Brothers Farmstead Cheese Company in Waterloo, Wisconsin.

The cheeses were sold under the Whole Foods label. Whole Foods said it has posted signs in its stores to notify consumers. Customers who purchased the product should discard it and bring in their receipt for a full refund.

Pregnant women, the elderly, and those with compromised immune systems are particularly at risk for illness after consuming Listeria-contaminated products. Healthy individuals usually do not get sick, but listeriosis can be extremely serious and in some cases fatal. Symptoms can range from high fever, headaches, and abdominal pain to miscarriages and stillbirths among pregnant women.

Health officials said the government’s Listeria Initiative also aided the swift response in this particular outbreak. Launched in 2004, the initiative asks state and local health departments to conduct standardized patient interviews as listeriosis cases are reported instead of waiting until after clusters are identified. When clinical pulsed-field gel electrophoresis (PFGE), a type of DNA fingerprinting, results are submitted to PulseNet and a cluster is identified, investigators are able to easily conduct an epidemiological investigation using the patient interviews, which include questions about what foods were consumed the month before they got sick.

“The listeria questionnaire was really helpful in solving this outbreak…because it’s a standardized questionnaire, it made it very easy to compare exposures between cases,” said Choi, in an email to Food Safety News.

Dr. Mahon at CDC agrees. She said the initiative has helped limit the impact of Listeria outbreaks because the public health response has gotten much faster than it was two decades ago. Even the catastrophic Listeria outbreak tied to Colorado cantaloupes is an example of rapid response. Had the investigation taken another week, or longer, thousands of pounds of potentially contaminated cantaloupes would have remained on the market.

“Back in the 80s, these types of investigations took weeks, even months,” said Mahon. “Six days is pretty good. We’re really starting to see this initiative pay off.”

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