Public health officials have issued a broad health warning about eating meats sliced at any deli counter, as they work to trace the source of a listeria outbreak that has killed at least two people and hospitalized at least 28 across a dozen states.

The Centers for Disease Control and Prevention issued a notice Friday that said people over 65, have a weakened immune system or are pregnant should not eat deli counter sliced meat unless it was reheated to an internal temperature of 165 F or was steaming hot. The groups singled out by the CDC are especially vulnerable to severe listeria infections.

Outbreak details

Cases tied to the outbreak range from people ages 32 to 94, with a median age of 74. The states with confirmed cases are Georgia, Illinois, Maryland, Massachusetts, Minnesota, Missouri, New Jersey, New York, North Carolina, Pennsylvania, Virginia and Wisconsin.

The true number of sick people may be higher than what has been reported, because it may take three to four weeks to determine whether a sick person is part of an outbreak and some people recover without medical care.

Advice for older adults

People who are pregnant, age 65 or older or have a weakened immune system should avoid eating meats sliced at any deli counter unless they are reheated to an internal temperature of 165°F or until steaming hot. Let the meat cool before consuming it, says the CDC.

In addition to the guidance about reheating deli meat, the CDC advises people to clean your refrigerator, containers and surfaces that may have touched the meats.

If you experience symptoms of a listeria infection, contact your doctor right away, the CDC stated. If you are diagnosed with an infection, work with your local or state health officials to provide details about what you ate in the month before getting sick.

“Listeria monocytogenes, the bacteria responsible for listeriosis, is ubiquitous in the environment and can thrive in various conditions, including refrigerated temperatures,” says Darin Detwiler, an associate professor at Northeastern University and a former FDA and USDA food safety advisor.

Listeria and Deli meats

The pathogen is easily spread via:

• Sharing Equipment Counters, slicers that are used to make multiple products may cross-contaminate the items if not cleaned and disinfected between uses.
• BiofilmsListeria forms biofilms when exposed to surfaces which makes it difficult to get rid of by regular cleaning.
• RefrigerationListeria is able to survive, and possibly increase in temperatures that are cold which increases the risk of cross-contamination with time.

Because of these causes even the meats that are initially safe could be contaminated when they come in contact with surfaces that are contaminated or equipment, according to Detwiler.

The signs of a listeria infection

Listeria illnesses pose a significant danger to those aged 65 or older. These people are four times more likely to be affected as per the CDC.

A sign of an infection with listeria include neck stiffness in addition to confusion, losing balance convulsions, fever fatigue and muscle pains.

Women who are pregnant typically experience discomfort, fatigue and fever pains. However, listeriariosis may cause loss of pregnancy or premature birth. Additionally, it could cause serious illness or even death for newborn babies. Anyone who is experiencing symptoms of severe listeria infection should contact their healthcare doctor.

Around 1,600 people within the U.S. get listeriosis each year, resulting in an average of 260 deaths per year, the CDC estimates.