Florida’s outbreak of listeria has so far led to at least one death, 22 hospitalizations, and an ice cream recall since January 2022. Humans get sick with listeria infections, called listeriosis, from eating soil-contaminated food, undercooked meat, or dairy products that are raw or unpasteurized. Listeria can cause convulsions, coma, miscarriage, and birth defects. It’s the third leading cause of food poisoning deaths in the United States.

Avoiding unseen food hazards is the reason people often check the dates on food packaging. Printed with the month and year is often one of a dizzying array of phrases: “best by,” “use by,” “best if used before,” “best if used by,” “guaranteed fresh until,” “freeze by,” and even a “born on” label applied to some beer.

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