Is it in your food?

One foodborne illness that can be very serious, especially for pregnant women, elderly individuals, or those with compromised immune systems, is listeria. Where does it come from? How can you prevent it in the first place? What’s the treatment for a listeria infection?


Listeria is a bacterium that is found in soil, water, and animal feces. This means you could end up infected with it if you eat raw vegetables that have been contaminated from the soil or manure used as fertilizer, contaminated meat, unpasteurized milk or foods made with unpasteurized milk, and certain processed foods (ex. soft cheeses, hot dogs and deli meats that have been contaminated after processing). Unborn babies can contract it from their mothers. It’s important to note that listeria can survive refrigeration and freezing.

The good news is that healthy people don’t usually become sick when infected with listeria. Many times, they don’t even have symptoms. Instead, it’s more of an issue for pregnant women, individuals over 65, and those with a weakened immune system, which include anyone who has AIDS, is receiving chemotherapy, has diabetes/kidney disease, takes prednisone/certain rheumatoid arthritis medication, or takes medication to block rejection of an organ transplant. For pregnant women, the risk to the mother is low, but the impact on the baby can be severe. It can result in miscarriage, stillbirth, premature birth, and a fatal infection after birth.

Symptoms usually appear a few days after ingesting contaminated food but can take as long as 30 days or more to show up. The most common symptoms are fever, chills, muscle aches, nausea, and diarrhea. If the bacteria spread to your nervous system, you might have a headache, stiff neck, loss of balance, confusion, changes in alertness, and convulsions. For newborns, symptoms are little interest in feeding, irritability, fever, vomiting, and difficulty breathing. There are two main complications of a listeria infection: generalized blood infection (sepsis) or inflammation of the membranes and fluid surrounding the brain (meningitis).


When treating listeria, those with mild infections don’t require any intervention because their body will fight it off. For severe infections, the usual treatment is antibiotics. During pregnancy, prompt treatment with antibiotics is essential to keeping the condition from impacting the baby.


When it comes to preventing a listeria infection, there are several things you can do. The most important is to wash your hands frequently and thoroughly with warm water and soap for at least 20 seconds. You should do this before and after handling/preparing food. Make sure to clean all utensils, cutting boards, and food prep areas with hot, soapy water. Clean all raw fruits and vegetables with water. It can be helpful to use a scrub brush. Make sure all of your food is cooked to a safe temperature. The best way to ensure this is by using a food thermometer.

Higher-risk individuals need to take additional precautions. It’s vital not to eat soft cheeses, like feta, brie, Camembert, blue cheese, or Mexican-style cheeses (ex. queso blanco and queso fresco). The only time it’s safe is if it’s clear on the packaging that the product was made using pasteurized milk. Avoid hot dogs and deli meats unless they’re reheated until steaming hot. Keep fluid from their packages away from other foods, utensils, and food preparation surfaces. Also, don’t eat refrigerated meat spreads. It’s okay to consume canned or shelf-stable meat spreads; just be sure to refrigerate them after opening. These products can be safely stored at room temperature before opening. Avoid smoked seafood, such as anything labeled nova style, lox, kippered, or jerky. If you eat sprouts, make sure they are thoroughly cooked.

While listeria doesn’t have much impact for most of us, it can cause major problems for some individuals. If you have any questions or concerns about listeria, please speak with your doctor. If you would like more information, please visit the Centers for Disease Control and Prevention’s (CDC) Listeria page at