If you’re making a salad for Thanksgiving dinner, skip the romaine lettuce this year. An E. coli outbreak linked to romaine has been detected in the US and Canada, the US Centers for Disease Control and Prevention announced on Tuesday.

As of November 20, the CDC’s official count of people affected by the outbreak reached 32 across 11 US states. Out of these, the CDC reported 13 hospitalizations and no deaths. In Canada, 18 people have been confirmed sick in Ontario and Quebec. The cases the CDC knows about were all reported between October 8 and October 31.

While investigators haven’t yet identified a specific farm or retailer responsible for the outbreak, CDC doctors have found the microbial culprit: Escherichia coli O157:H7 — E. coli O157:H7 for short. This strain of the bacterium can be particularly nasty because it produces a substance known as shiga toxin.

For more information on E. coli and shiga toxin, check out the video at the top of this article. It was made during an outbreak this spring, but all the information in it still applies to the current outbreak.

November 20, 2018 e. Coli map

Since the CDC hasn’t nailed down a source of the E. coli, it’s currently recommending that consumers don’t eat any romaine lettuce. The health agency advises that you throw out any romaine lettuce you have in your home, even if someone has already eaten it and not gotten sick. This includes whole romaine heads, chopped romaine, salad mixes that contain romaine, romaine hearts, Caesar salad, and literally any salad that may contain romaine lettuce.

It’s also crucial to note that the CDC does not recommend antibiotics for people who get sick with E. coli O157:H7. Not only are doctors not sure whether antibiotics can even help treat this type of infection, but antibiotics have been found to increase your risk of developing hemolytic uremic syndrome, a type of kidney failure.

If you do get sick and suspect you may have eaten romaine lettuce, seek medical attention so your doctor can confirm infection with a stool sample. In most cases, people get sick between two and eight days after eating contaminated food, and in most cases, infections are mild. However, if you develop a high fever and notice your poop is black, seek immediate medical attention. This could indicate that you’ve developed a particularly severe infection.

So now that we’re all in the mood to start prepping for dinner, how about reaching for a nice spinach or kale?