Ten people in three Northeastern states are now believed to have died due to a string of Listeria infections caused by contaminated food. On Friday, the United States Food and Drug Administration and the U.S. Department of Agriculture issued a warning about a recent increase in cases of Listeria monocytogenes in Pennsylvania. More cases, however, have been detected in Michigan, Maryland, New Jersey, New York and Connecticut. Four deaths were reported in New Jersey, four in Pennsylvania and two in New York City. Investigators have yet to determine the cause of the recent outbreaks, but officials say the Listeria strains are all similar.

Listeria-contaminated food products can cause miscarriages and stillbirths among pregnant women, as well as serious and sometimes fatal infections in newborns, frail or elderly people, and others with weakened immune systems. Healthy individuals may suffer only short-term symptoms such as high fever, severe headache, stiffness, nausea, abdominal pain and diarrhea.