Image
![](/sites/default/files/styles/extra_large/public/16744/2024-02/workers_in_a_lab_img_0020.jpg?itok=1WWjzqrh)
The CDC's timeline linking one source after a period of ten-years of outbreaks substantiates the fact listeria is a hardy germ that can be difficult to fully remove from food processing facilities. Listeria can also survive in the refrigerator and easily contaminate other foods and surfaces.
DNA fingerprinting is performed on bacteria using using the PulseNet system to identify illnesses that may be part of this outbreak. The CDC PulseNet manages a national database of DNA fingerprints of bacteria that cause foodborne illnesses.
By utilizing whole genome sequencing (WGS) bacteria from sick people’s samples from 2014 to present were identified as closely related genetically. The conclusion was they got sick from the same food:
Investigation Details | Listeria Outbreak Linked to Queso Fresco and Cotija Cheese | CDC
Unrelated to the cheese and dairy products from this outbreak is a concern about Enoki Mushrooms
Because of recent outbreaks, the CDC is currently working to understand the risk of Listeria infection from enoki mushrooms. While this work is happening, the CDC advises people who are pregnant, aged 65 or older, or have a weakened immune system to not eat raw enoki mushrooms. Instead, cook enoki mushrooms thoroughly, and ask that restaurants cook them thoroughly. See more scientific papers on the CDC Listeria publications page.
The true number of sick people in this outbreak is likely higher than the number reported, and the outbreak may not be limited to the states with known illnesses. This is because some people recover without medical care and are not tested for Listeria. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak.
According to the CDC website: