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Listeria surveillance in the deadly Blue Bell ice cream food poisoning outbreak has advanced to include Whole Genome Sequencing, a tool for examining the DNA code of human pathogens that is second to none in accuracy. According to the Centers for Disease Control and Prevention (CDC), Whole Genome Sequencing, or WGS, of the Listeria monocytogenes isolates obtained from Blue Bell ice cream by Texas health officials was set in progress earlier this month.

Kansas Blue Bell lawsuits on behalf of victims seeking compensation for their illnesses undoubtedly will incorporate the results, as will state and federal epidemiologists who are trying to get an accurate picture of how many people outside Kansas were infected. As explained in a CDC You Tube video, WGS provides the most detailed look available of DNA molecules in food poisoning pathogens. The results allow judges, lawyers, educators and infectious disease trackers to distinguish one strain of Listeria monocytogenes from another. If someone falls ill with listeriosis in any part of the country, WGS can determine if the case belongs to the Blue Bell outbreak.

CDC’s initial Listeria ice cream report on March 13 demonstrated five illnesses within Kansas from four strains of L. monocytogenes associated with Blue Bell ice cream. The matches were made possible by initial testing of ice cream samples — all made on the same production line at Blue Bell’s Brenham, Texas, plant. Those initial findings were based on widely used technology known as pulsed-field gel electrophoresis (PFGE). The Blue Bell brand ice cream products with tests showing Listeria monocytogenes were single-serve Scoops, Chocolate Chip Country Cookie Sandwiches, and Great Divide Bars. The company has withdrawn those products from the marketplace, along with seven other single-serve products made with the same machinery. But officials still fear people could fall ill from products stored in home freezers. Listeria is an organism that survives, even multiplies, in freezing temperatures.