The investigation into a Listeriosis outbreak traced to frozen vegetables from CRF Frozen Foods Inc. has ended — but federal officials warn more people could still be stricken by the potentially deadly Listeria monocytogenes pathogen. “People could continue to get sick because recalled products may still be freezers and people who don’t know about the recalls could eat them,” according to an outbreak update posted this afternoon by the federal Centers for Disease Control and Prevention (CDC) in Atlanta. “Retailers should not sell and consumers should not eat recalled products.” Those “recalled products” include more than 350 frozen products packaged by CRF Frozen Foods Inc. under 42 brands, according to the Food and Drug Administration (FDA).  Recalled products were sold across the U.S. and Canada. “The FDA facilitated the recall of at least 456 products related to this outbreak. CRF Frozen Foods recalled 358 products and at least 98 other products were recalled by other firms that received CRF-recalled products,” according to FDA. A complete list of the recalls linked to CRF Frozen Foods’ recall is available on the FDA website. Production plant remains closed CRF owners closed the Pasco, WA, plant where the food was produced after issuing recalls on April 23 and May 2. The first recall was for 11 frozen vegetable products. The second was for all organic and traditional frozen vegetable and fruit products processed at the facility from May 1, 2014, through this spring. Today an external public relations consultant hired by CRF said the company’s owners will take their time reopening the facility. He said CRF’s business is seasonal, based on crop harvests, and with the end of summer nearing it wouldn’t make any difference if they reopened in a few weeks or a few months.

“The company executives are spending a good bit of time and effort focused on a new design of the plant, to ensure the company has state of the art equipment and processes, once operations resume,” said spokesman Gene Grabowski. Officials with the privately held CRF, which is part of the R.D. Offutt Co., were pleased that the outbreak investigation was declared ended, Grabowski said this afternoon, adding that they would “continue to proceed with redoubled vigilance to ensure that nothing of this nature happens again.” Although CRF knows how much product it shipped, its officials did not reveal those volumes in its recall notices. “The company has no estimate of product recalled or destroyed,” Grabovski said. “Much of the recalled product has been managed by retailers, so no complete records are available.” The victims and how they were discovered The outbreak includes at least nine people from four states on opposite sides of the U.S. They were sickened with a strain of Listeria monocytogenes that Ohio officials coincidentally discovered in CRF frozen products while conducting routine testing of randomly collected packages of frozen foods from retail stores. All nine people were so sick they had to be hospitalized. Three of them died, but state public health officials reported to the CDC that only one of the deaths was specifically caused by the Listeria infection. The first known victim became sick in September of 2013. Five victims fell ill in 2015 and three were confirmed with the outbreak strain this year. The most recent case was May 3, according to the CDC. CDC scientists detected the outbreak in March this year and linked it to frozen food from CRF’s Pasco plant using a combination of high-tech DNA testing and the oldest medical technique on the books — patient interviews. “State and local health departments attempted to interview the ill people, a family member, or a caregiver for the ill person about the foods the ill person may have eaten in the month before the illness began,” CDC reported. Officials were able to interview four people, three of whom reported that before they became sick they ate frozen vegetables that turned out to have been produced at the CRF Pasco plant. “Two reported Organic by Nature brand frozen vegetables. The third ill person reported eating O Organic brand frozen vegetables,” CDC reported. While the CDC investigators were trying to find a common denominator among the Listeria victims, staff with the Ohio Department of Agriculture were conducting routine, random product sampling of frozen vegetables from grocery stores. The Ohio tests revealed Listeria monocytogenes in frozen organic white sweet corn and frozen organic green peas packaged under Meijer’s True Goodness brand. Both products were produced by CRF at the Pasco facility. “Whole genome sequencing showed that the Listeria isolate from the frozen corn was closely related genetically to eight bacterial isolates from (the) ill people, and the Listeria isolate from the frozen peas was closely related genetically to one isolate from (one) ill person,” the CDC reported. Public health investigators used the PulseNet system to compare and ultimately match the Listeria monocytogenes samples from the outbreak victims and the randomly tested frozen vegetables. PulseNet is a national sub typing network of public health labs and includes a national database of DNA fingerprints of foodborne pathogen strains. (To sign up for a free subscription to Food Safety News, click here.)