Listeria Infection: Will That Melon Make Me Sick?

Listeria-laden cantaloupes have caused 25 deaths so far this year in the worst listeriosis outbreak in 25 years, according to the Centers for Disease Control and Prevention. The CDC reports 17 cantaloupe-related listeria infections in Texas.

Are the cantaloupes you’re eating safe?

Probably. The affected cantaloupes from Jensen Farms in Colorado were recalled in mid-September. They should no longer be available.

However, you may not be out of danger. Because listeriosis can take as long as two months to develop into full-blown illness, symptoms may not show until November.

“The infection is avoided by the careful handling and cooking of foods, especially processed meat.”

Robert Plemmons, MD, Infectious Disease, describes Listeria infection (listeriosis) and offers some tips on its treatment and prevention.

What Is Listeria?

Listeria is a bacterium, as opposed to a fungus, virus, or parasite,” explains Dr. Plemmons. The scientific name for the bacterium is Listeria monocytogenes.

It lives in soil and can contaminate plants and subsequently infect animals grazing on those plants.


“It’s usually transmitted to humans via contaminated food, often meat, but most recently melons,” Dr. Plemmons explains.

Listeria monocytogenes may contaminate these foods commonly found in your refrigerator:

  • Hot dogs
  • Deli meats
  • Smoked seafood
  • Soft cheeses, such as feta or queso blanco
  • Produce, such as melons and romaine lettuce

Listeria is generally killed by pasteurization and cooking, but contamination with Listeria can still occur if there are unrecognized lapses in cleanliness during the processing and packaging of cooked foods, Dr. Plemmons explains.

Listeria, unlike other bacteria, can multiply and grow at refrigerator temperatures.

What Are the Symptoms of Listeriosis?

Gastrointestinal ailments are the most common symptoms of Listeria infection. “It often causes vomiting and diarrhea, but can also cause bloodstream infection and meningitis,” Dr. Plemmons says.

In addition to digestive distress, you may experience these symptoms:

  • Fever
  • Muscle aches
  • Stiff neck

In pregnant women, listeriosis can induce miscarriage and stillbirth.

Who Is Most at Risk?

“The germ Listeria monocytogenes may cause infection after it is ingested by a susceptible person,” Dr. Plemmons explains. If a healthy person eats food infected with Listeria, he or she may become ill, but “healthier people generally survive,” Dr. Plemmons says.

However, “those who are immunocompromised are less likely to survive, especially if they have brain abscess or meningitis,” Dr. Plemmons warns.

According to the CDC, other groups for whom Listeria infection may be very serious are:

  • Pregnant women
  • Newborn babies
  • Persons with cancer, diabetes, alcoholism, AIDS, liver or kidney disease
  • The elderly

How Is Listeriosis Diagnosed?

Dr. Plemmons says the disease is diagnosed by cultures of your:

  • Blood
  • Spinal fluid
  • Stool

How Is Listeriosis Treated?

Listeriosis is treated with antibiotics, usually ampicillin (or trimethoprim/ sulfamethoxazole if you’re penicillin allergic), says Dr. Plemmons.

Even with antibiotic treatment, listeriosis can be dangerous for people with compromised immune systems. “The mortality rate from Listeria infection is about 20 percent overall in the United States. Also, Listeria infections account for about 30 percent of all deaths due to food-borne disease in the U.S.,” says Dr. Plemmons.

If you suspect you have Listeria infection, it’s important that you seek medical attention. Tell your physician if you think you may have eaten contaminated food.

How Is Listeriosis Prevented?

“The infection is avoided by the careful handling and cooking of foods, especially processed meat,” Dr. Plemmons says.

CDC guidelines for careful food handling to prevent listeriosis include:

  • Rinse all raw fruits and vegetables, even if you will peel them.
  • Scrub firm produce, such as melons and cucumbers.
  • Dry produce with a clean cloth or paper towel.
  • Separate meats from your vegetables and other foods.
  • Store opened hot dog packages no more than seven days and opened deli meat packages no more than five days. Throw away unopened packages after two weeks.
  • Avoid getting fluids from hot dogs and deli meats on other foods, utensils or food preparation surfaces.
  • Clean up all spills in your refrigerator with hot, soapy water right away.
  • Thoroughly cook all raw meat.
  • Keep your refrigerator at 40°F or lower to help prevent the growth of Listeria.

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Listeria Infection: Will That Melon Make Me Sick?