As of November 20, an E. coli outbreak linked to romaine lettuce had hospitalized 13 people, and the CDC is asking that "consumers not eat any romaine lettuce, and retailers and restaurants not serve or sell any, until we learn more about the outbreak." NBC News reports that 32 people in several states have been infected thus far.
E. coli is so dangerous because strains like this one produce the toxin Shiga, which can lead to kidney failure. Sickness usually starts between two to eight days after contact, but on average symptoms show around day three or four. The agency has gone so far as to warn, "If you do not know if the lettuce is romaine or whether a salad mix contains romaine, do not eat it and throw it away."
Maybe consider this your opportunity to appreciate all the other Thanksgiving sides.