The germ has been found before on raw produce and even in store-bought hummus.

Every time a listeria outbreak occurs, it’s easy to worry that you might have consumed whatever food has been found to contain this strain of bacteria. (You might recall the deadliest outbreak traced back to cantaloupe from a Colorado farm in 2011.)

To make us all even more worried, the list of listeria-affected foods has expanded beyond the usual deli meats, hot dogs, smoked seafood, produce, and dairy products to even include packaged picks like frozen burritos and hummus.

Listeria is a type of bacteria that causes food poisoning. The number-one way it gets into food is through contaminated soil and water, and animals can carry it too, says Amanda Deering, PhD, a clinical assistant professor in the Department of Food Science at Purdue University.

But listeria can also reach your food while it’s on its way to you. “Contamination can happen after a food is harvested if listeria has established itself in the packing house,” Deering says. “Then the produce becomes contaminated through cross-contamination after being in contact with surfaces that contain it.”

If you’ve been exposed to listeria, you may not even realize it, as the symptoms might make you feel like you have the flu. You might also not even experience anything until a few days or even weeks after you’ve consumed a food that’s been compromised.

That said, if you do have listeria symptoms, you’ll likely experience these classic signs:

  • Fever
  • Vomiting
  • Diarrhea
  • Muscle aches
  • Headache

Listeria symptoms should resolve over the course of a few days. However, if a listeria infection—technically called listeriosis—spreads to your nervous system, the signs can include loss of balance, confusion, stiff neck, tremors, and convulsions. This is called invasive listeriosis, and it can take up to 70 days for these symptoms to appear. Invasive listeriosis symptoms can last for weeks and may even lead to sepsis or meningitis, according to the CDC.

If you’re pregnant, immune-compromised, or elderly, be warned: Listeria is more serious for you and can lead to life-threatening complications.

The best way to avoid listeria is to keep your kitchen surfaces germ-free, rinse raw produce thoroughly, make sure your refrigerator is kept clean (as listeria bacteria can multiply even when refrigerated), and cook your food thoroughly, Deering says.

“By cooking your food, this will kill any bacteria that are present to ensure that it’s safe for consumption,” she says.

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