Exposure can lead to muscle aches, diarrhea and more.
"Stiff neck, fever, headaches. It can cause convulsions and it ultimately can cause death," Watts says.
Prevention starts with good food hygiene. Keep your refrigerator at 40 degrees and make sure food is properly stored in plastic wrap or storage containers.
"A really great way to prevent the spread of listeria is to keep our hands clean when we're prepping foods. Keep the veggies clean before they enter the refrigerator so you're not putting listeria from the enviroment, the soil into the refrigerator. Keep our workspaces clean while we're cooking, don't use the same cutting board for uncooked poultry that you would use to cut veggies," Watts says.
While anyone can be infect, those most at risk include the very young, the very old, pregnant women and patients with a compromised immune system.