The CDC issued a warning about Friday’s outbreak, which sent ten people from Florida, Massachusetts and New York to the hospital and led to the death of one person in Florida.
Deli meat was the possible source of the epidemic, the agency said. Nine victims reported eating Italian-style meats, such as salami, although the CDC has not yet identified it as common meat or source.
The mean age of those infected was 81 and most were women. While many are unlikely to get seriously ill from Listeria, people aged 65 and over, people with weakened immune systems and pregnant women are at higher risk of getting sick.
Listeria can be especially dangerous for pregnant women. Infection during pregnancy can lead to miscarriage, childbirth, premature birth or life-threatening infection of the newborn.
Symptoms of infection usually begin one to four weeks after eating contaminated food and may include fever, muscle aches, headache, confusion, and loss of balance.
Previous cases of Listeria have been linked to hard boiled eggs, mushrooms and soft cheeses.
The CDC advises those at high risk of infection to avoid eating cold cuts unless they are well warmed up first. The agency also advises storing meat in the refrigerator, away from other foods and keeping surrounding surfaces clean.
The investigation into the outbreak continues.