Outbreak alert: Listeria monocytogenes in deli meats and cheeses

Four U.S. states have been affected by an outbreak of Listeria monocytogenes, a hardy foodborne pathogen that can survive in a variety of environments, making it challenging for food producers and processors to eradicate in their facilities.

The bacteria has sickened eight people in the ongoing outbreak, resulting in one death. The states impacted are Michigan, New Jersey, New York and Pennsylvania.

Authorities haven’t named a specific supplier of food products, but the outbreak is associated with deli counter products — cheeses and ready-to-eat meats — from several different stores. At this time, the U.S. Centers for Disease Control and Prevention (CDC) is not advising consumers to avoid eating at delis or buying deli-sliced products.

The earliest cases involved with this outbreak date from November 2016, according to the CDC, making this a long-running outbreak. Investigators are still looking into the origin of the outbreak.

It's not uncommon for Listeria monocytogenes to be associated with ready-to-eat meat products. In fact, the largest recorded foodborne illness outbreak of all time was linked to a ready-to-eat meat product in South Africa.

About the strain

Listeria monocytogenes is a hardy bacteria that can adapt well to a wide variety of environments, including cold temperatures, and can readily colonize on most surfaces.

When a person is infected, symptoms can take two to three weeks to appear, which can hamper traceback investigations, as it becomes difficult to pinpoint what the person has eaten. Symptoms usually include diarrhea, nausea, fever and muscle aches. For pregnant women, infections are more worrisome, and can lead to fetal loss or harm to the newborn. Older individuals and people with weakened immune systems also face greater risks.

While most infected people recover after a few days without treatment, Listeria monocytogenes infections can progress rapidly to life-threatening sepsis faster than most other foodborne pathogens. Listeriosis cases can be prevented when food producers exercise rigorous cleaning and monitoring programs, and when consumers keep their own kitchens clean, and always cook food to an adequate temperature.