Last month, when health officials reported they discovered a pathogenic connection between raw milk from a Pennsylvania dairy and two illnesses in 2014 — one in California and the other in Florida — a wave of disbelief and condemnation began rippling out from the raw milk community, according to Food Safety News.
News stories about the announcement from the Centers for Disease Control and Prevention (CDC) sparked a flurry of online comments from raw milk drinkers and producers who disparaged the government’s science and scientists.
A common thread through many of the posts was disbelief that laboratory analysis could actually prove the pathogen samples from the two patients and the dairy were the same strain of Listeria monocytogenes.
Raw milk advocates questioned why the CDC said only that the samples were “closely related genetically” and that Miller’s Organic Farm in Pennsylvania was the “likely source.” Conspiracy theories about a big government agenda to destroy the raw milk industry emerged as fans of unpasteurized raw dairy products questioned why a specific dairy was being targeted when the CDC would not definitively state their lab analysis was 100 percent correct.
The CDC used whole genome sequencing (WGS) to analyze the DNA of the Listeria from a sample of Miller’s Organic Farm raw milk. That DNA fingerprint of “about 2 million base pairs” was then fed into the PulseNet database, said Matthew Wise, the outbreak response team lead in CDC’s division of foodborne, waterborne, and environmental diseases.
The database already included the DNA fingerprints from the Listeria monocytogenes that sickened the California and Florida patients. When the CDC scientists added the database and ran a search for matches, the connection was discovered.
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