According to the CDC, the outbreak now consists of two clusters of illnesses that are likely linked to Blue Bell brand ice cream products. The outbreak involves eight people infected with outbreak strains of Listeria monocytogenes; eight people are reported from Kansas (5) and Texas (3).
Cluster 1 consists of five patients reported from Kansas during January 2014 through January 2015 who were all hospitalized at a single hospital for unrelated problems before developing listeriosis. Of the four ill people for whom information is available on the foods eaten in the month before Listeria infection, all consumed milkshakes made at the hospital with a Blue Bell brand ice cream product called “Scoops.” Whole genome sequences of Listeria monocytogenes strains isolated from four of the patients were found to be highly related to sequences of Listeria strains isolated from “Scoops” and two other products made on the same line at the company’s Texas facility. These products were recalled by Blue Bell Creameries on March 13, 2015.
Cluster 2 consists of three patients reported from Texas during 2011 through 2014 who were all hospitalized for unrelated problems before developing listeriosis. Whole genome sequences of their Listeria monocytogenes strains were highly related to sequences of Listeria strains isolated from another Blue Bell ice cream product, 3 oz. institutional/food service chocolate ice cream cups made at the Oklahoma production facility. The cup products were recalled by Blue Bell Creameries on March 23, 2015.
Three additional patients with listeriosis during 2010 through 2012 whose isolates have PFGE patterns similar to those of others in the cluster have been identified in the PulseNet database; further molecular laboratory testing is under way to determine whether these illnesses may be related to this outbreak.