The Centers for Disease Control and Prevention (CDC) has ended its investigation into the Blue Bell Listeria outbreak. Since its last update in early May, the agency added no new cases ending its probe of food safety problems at the nation’s third-largest ice cream maker with 10 cases reported from four states and three fatalities.
Several strains of Listeria were involved. Most of the confirmed cases-Arizona (1), Kansas (5), Oklahoma (1), and Texas (3); were sickened by strains identical to those found in ice cream made at the company’s plants in Brenham, Texas and Broken Arrow, Okla. The three fatalities were in Kansas.
Using PulseNet, a national database that allows public health agencies to share pathogen “fingerprints,” health officials retrospectively identified illnesses that were part of the outbreak. The earliest cases were identified in 2010, the most recent were in January 2015. The eight Kansas and Texas cases were hospital patients who were served contaminated Blue Bell ice cream during their stays.
In Kansas, the five patients all ate ice cream or milkshakes made from a Blue Bell single-serving product called Scoops. The Listeria isolates from four of those patients were “highly related to each other by whole genome sequencing,” according to the CDC. “The isolate from the fifth person was not related to isolates from the other four ill people. In addition, the PFGE pattern was not identified in any ice cream samples. However, this person was part of a recognized illness cluster at the hospital and consumed milkshakes made with “Scoops” while hospitalized. As a result, this person was included as a case in the outbreak,” the CDC stated in its report.
After the Kansas patients were identified, the hospital was told to put all Bell Bell products in quarantine. Testing on these products found Listeria in single serving chocolate ice cream cups. This strain did not match the one that sickened the Kansas patients, but it did match the strain in other chocolate cups made at the company’s Broken Arrow facility and a strain found in three hospital patients in Texas.
After the ice cream was linked to the outbreak, Blue Bell began a series of product recalls, eventually recalling all of its products on April 20. Consumers who may still have Blue Blue products in their freezers should not eat them.
The five-year span of the outbreak uncovered a longstanding Listeria problem at Blue Bell’s Texas and Oklahoma plants. And reports released by the U.S. Food and Drug Administration (FDA) on May 7 showed the company was aware of Listeria in its plants in 2013 but did not test the bacteria to discover if it was pathogenic or take measures to eradicate the problem.