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Listeria outbreak linked to deli meats. Those who are pregnant are at severe risk, Northeastern expert warns

Detwiler advises those who are pregnant — as well as older adults and immunocompromised individuals — to heat meats sliced at a deli to an internal temperature of at least 165 degrees to kill any listeria present.

Rows of cold cut meats.
Cold cuts sliced at the deli are linked to a deadly listeria outbreak. Experts advise those who are pregnant to cook cold cuts until they are steaming hot for safety, then cool. Getty Images

When Northeastern University food policy expert Darin Detwiler hears about outbreaks of listeria like the one linked to deli meat that has hospitalized 28 people, he immediately thinks of the risk to those who are pregnant.

“Pregnancy alters the immune system, making pregnant women more susceptible to infections, including listeriosis,” says Detwiler, an associate teaching professor.

Even if the woman recovers with appropriate antibiotic treatment, “the unborn child can suffer severe consequences,” including stillbirth or long-term health issues, he says.

The Centers for Disease Control and Prevention says the current listeria outbreak is located in 12 states and has resulted in two deaths, one apiece in New Jersey and Illinois.

One of the people hospitalized included an expectant mother. According to federal health officials, she has recovered and the pregnancy remains intact.

The CDC says of 18 patients able to be interviewed by state and local public health officials, 16 reported eating meats sliced at a deli, most commonly deli-sliced turkey, liverwurst and ham.

Cook your cold cuts 

Deli meats are a common vector for contamination with listeria, a type of bacterial illness that can spread from the gut to other parts of the body “due to their processing, handling and storage characteristics,” Detwiler says.

“The high moisture and nutrient content of deli meats create an ideal environment for listeria growth,” he says. 

Headshot of Darin Detwiler.
Darin Detwiler, associate teaching professor, advises pregnant mothers to cook deli meat to avoid dangerous listeria infection. Photo by Matthew Modoono/Northeastern University

Processing and handling create more opportunities for contamination, Detwiler says. The fact that deli meats are often stored for extended periods, allows “time for listeria to proliferate if present,” he says.

Detwiler advises those who are pregnant — as well as older adults and immunocompromised individuals — to heat meats sliced at a deli to an internal temperature of at least 165 degrees before eating it to kill any listeria present.

That means heating the deli meat until it’s steaming hot, then letting it cool, the CDC says.

Risk to expectant mothers and unborn children 

Listeria poses a particular health risk for expectant mothers and an even higher risk for the unborn child, Detwiler says.

“What most people do not understand are the severe consequences for the unborn child,” he says. 

Pregnancy reduces the immune system’s capacity to fight off infections, increasing the risk of a woman contracting listeriosis, Detwiler says, adding that the bacteria can cross the placental barrier, infecting the uterus.

“This can lead to severe and often fatal outcomes for the unborn child, including miscarriage, stillbirth, preterm labor or neonatal infection.”

A pregnant woman may find a listeria infection limited to mild flu-like symptoms such as fever, muscle aches and gastrointestinal symptoms, Detwiler says.

“She can often recover with appropriate antibiotic treatment (but) the unborn child can suffer severe consequences,” he says.

“If the baby is born alive, they may suffer from neonatal listeriosis, which can cause severe complications such as sepsis, meningitis and long-term health issues.”

Detwiler says about 20% of listeriosis cases in those who are pregnant result in fetal loss and  50% in preterm delivery.

“The mortality rate for newborns with listeriosis is high, ranging from 20% to 30%, despite treatment,” he says.

The CDC says patient samples were collected from May 29 to July 5, but recent illnesses may not have been reported because it takes three to four weeks to determine if a sick person is part of an outbreak.

“The true number of sick people in this outbreak is likely higher than the number reported, and the outbreak may not be limited to the states with known illnesses,” according to the CDC. 

Additional safety tips

The CDC asks people to contact their health care providers if they experience any of the following symptoms: fever, muscle aches, fatigue, headaches, stiff necks, confusion, loss of balance and seizures.

To prevent listeriosis infections from sliced deli meats, Detwiler also advises people to check expiration dates, consume meats within three to five days of opening, and to store the cold cuts at or below 40 degrees in the refrigerator.

As an additional precaution, he says to use separate cutting boards and utensils for raw and cooked foods.