So far, California reported seven cases, while Illinois recorded two, with single cases in New York and New Jersey. The CDC warned that the actual number of sick individuals could be significantly higher since some recover without medical help and may not undergo testing. The agency also noted that the confirmation of recent cases often takes three to four weeks.

Listeria, a harmful bacterium, can lead to listeriosis, a severe infection that primarily threatens vulnerable populations such as older adults, pregnant women, and newborns. Symptoms of listeriosis include fever, muscle pains, and gastrointestinal distress, and it is the third leading cause of death from foodborne illness in the United States. The CDC estimates that there are 1,600 infections and around 200 deaths from listeria each year.