The Listeria Outbreak: Your Questions Answered

Since the first cases of Listeria-related infection were reported in late May of this year—the biggest Listeria outbreak since 2011—57 people have been hospitalized and 9 have died.

The source of the outbreak has since been identified: Boar’s Head sliced and ready-to-eat meats, which are normally sold at grocery stores and delis across the country. By late July, all Boar’s Head deli meats had been recalled. But that does’t mean we’re out of the woods just yet, as some people may still have contaminated meat and poultry products on their refrigerator shelves.

While the risk of serious illness is low, the public’s concerns still run high, even after the recall. The best way to allay these concerns is through accurate information.

Enter Dr. Heidi Torres, Assistant Professor of Clinical Medicine in the Division of Infectious Diseases and Assistant Hospital Epidemiologist at 鶹ý, who has been following this story since it came to light in late May. Continue reading for her answers to your FAQs concerning how to stay safe from Listeria-related illness this fall.

What is Listeria?

Listeria are bacteria that can cause listeriosisan infection of the GI tract (gastroenteritis) or, rarely, a more invasive illness such as meningitis or bacteria in the blood,” Dr. Torres says. People who are healthy and have normal immune systems rarely become sick from Listeria, but listeriosis can be serious in individuals at risk.

Who may be at risk for severe illness?

Most people with normal immune systems will not develop illness after exposure to Listeria. However, the following groups are at risk for severe illness:

  • people who are immunocompromised due to illness or immunosuppressant medications
  • infants and the elderly
  • pregnant women

Is listeriosis always food-borne?

Listeriosis is most often food-borne,” she says. “The bacterium can be found naturally in soil and water, and it can infect animals and show up in their feces or milk. Therefore, food is often contaminated during its growth or processing.

“For example,” she continues, “vegetables can be contaminated from the soil; deli meats can be contaminated in food processing facilities; and the bacteria can live in raw animal milk.

According to the Centers for Disease Control and Prevention (CDC), Listeria is a hardy germ that can remain on surfaces, like meat slicers, and in foods, even at refrigerated temperatures.

Foods commonly linked to Listeria include:

  • undercooked meats
  • raw or smoked fish
  • fruits and vegetables
  • deli meats and hot dogs
  • unpasteurized milk and products made from it, such as soft cheeses

Those who are pregnant, even if asymptomatic, can also pass the bacteria to their baby. As Listeria can cause severe or even fatal disease in a fetus or baby, Dr. Torres adds, “certain foods should be avoided during pregnancy, such as soft cheeses, raw sprouts and undercooked meats.

How serious is the current outbreak in New York City and the environment?

The current Listeria outbreak is the largest one in over a decade. The greatest number of cases have been reported in New York State, with 17 across the state and 8 in New York City alone.

How does it spread?

Listeria is usually spread by eating contaminated food, she says. However, “aside from a pregnant woman passing the bacteria or infection to a fetus, Listeria does’t otherwise spread from person to person.

How do you diagnose listeriosis?

Intestinal listeriosis is commonly diagnosed based on symptoms and a history of consuming foods likely to be contaminated with Listeria. In invasive disease, the presence of the bacteria can be evaluated in blood or spinal fluid samples.

What are its main symptoms?

The symptoms of gastroenteritis or intestinal infection caused by Listeria will often include:

  • nausea
  • diarrhea
  • fever
  • chills
  • muscle aches

These symptoms usually only last a few days.

While rare, however, the infection can become invasive and spread to your blood,” she continues. “In that case, you may develop sepsis—a life-threatening complication of an infection. And if it spreads to your brain or spinal cord, you may develop fever, headache, vomiting, neck stiffness, sensitivity to light, confusion, drowsiness, weakness on one side of your body, tremors or seizures. Infants infected through their dzٳ’s placenta can develop sepsis, multi-organ abscesses or meningitis.

How is listeriosis treated?

For mild intestinal illness, supportive care—fluids and rest—is the only treatment indicated, she says.

Antibiotic treatment will likely be needed if the patient

  • is pregnant
  • has severe symptoms
  • has risk factors for severe disease
  • shows signs of invasive disease

How can people protect themselves from getting infected?

Dr. Torres offers the following list of steps we can take to protect ourselves and our loved ones from Listeria infection:

  • clean raw vegetables and fruits
  • cook meat thoroughly
  • heat deli meats or cheeses to 165°F or until steaming
  • avoid unpasteurized milk and products made with it

As far as the current outbreak is concerned, many Boar’s Head products with sell-by dates from July 29 to October 17 have been recalled and should not be consumed.

For the full list of recalled products, visit the US Department of Agriculture’s Food Safety and Inspection Service .

Remember, it can take up to 10 weeks for some people to have symptoms of listeriosis.

Just in case, check your fridge for any remaining recalled Boar's Head products, as these can have long a shelf-life. Look for EST. 12612 or P-12612 inside the USDA mark of inspection on the product labels. Some of these products have sell-by dates well into October 2024.

When should people make an appointment to see their primary care provider?

If signs or symptoms of Listeria infection develop after eating raw vegetables, soft cheeses, processed meats, raw milk or any recalled foods, seek medical care—e𳦾 if you’re immunocompromised, pregnant, have signs of invasive disease or have ongoing symptoms that do’t improve,” Dr. Torres advises.

If you suspect that you have been exposed to Listeria, or if you’re experiencing any of the symptoms described above, make an appointment with an infectious disease specialist.

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