How to Avoid Listeria

Three Parts:Avoiding Potentially Contaminated FoodsStoring and Handling Foods Safely at HomeMonitoring Any Symptoms or Side Effects

Listeria is a bacteria that can be found in some foods. When eaten, it can cause an infection called listeriosis, which can cause symptoms like diarrhea, fever, muscle aches and headaches;[1] however, some may be more at risk for more severe and dangerous side effects from listeriosis. Infants, older adults, pregnant women and those with compromised immune systems are at a higher risk from the symptoms caused by this harmful bacteria. It's important to stay aware of what types of foods can harbor Listeria, the conditions in which it can grow (Listeria is unusual in that it can grow and spread in the refrigerator and even frozen foods can maintain the bacteria), and how you can prevent contamination of your foods so you can stay safe and avoid a serious infection.

Part 1
Avoiding Potentially Contaminated Foods

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    Avoid raw dairy foods. Raw dairy products, like milk or cheese, are more available in supermarkets and farmers markets. Although these foods may taste good, they can also be a source of the Listeria bacteria.[2] Avoiding these foods can help minimize your risk of contracting this bacteria.
    • A study by the FDA showed that consuming raw or unpasteurized dairy products are 150 times more likely to cause foodborne illness (from bacteria like listeria) and 13 times more likely to cause hospitalization compared to pasteurized dairy products.
    • Dairy products like milk or cheese are the most common raw and unpasteurized products that you may come across. They have not gone through the process of pasteurization which helps kill off harmful bacteria.
    • In addition to Listeria, raw dairy products can also contain both the Salmonella and E.Coli bacterium as well.
    • Only consume pasteurized milk and cheese. Avoid raw milk, raw cheese or fresh cheeses as these may be sources of Listeria.
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    Limit your intake of deli meats and meat salads. Like raw dairy products, another very common source of Listeria is deli meat and pre-prepared meat salads (like chicken or tuna salad). Limiting your consumption of these foods or changing the way you prepare them can help you avoid contamination with Listeria.[3]
    • Deli meats, hot dogs and pre-prepared meat salads can contain Listeria because this bacteria can grow even at colder temperatures. Also avoid pâté and other meat spreads that are in the refrigerated section of the grocery store.
    • In addition, deli meat is typically never reheated prior to eating. Only heating foods to a proper temperature of at least 160°F (71.1°C) can kill Listeria bacteria.[4] If you want to eat deli meat, microwave it or cook it in a pan until a thermometer says the internal temperature is 160°F (71.1°C).
    • However, it's difficult to reheat items like tuna or chicken salad, so it may be best to avoid these foods altogether — especially if you're part of an at risk population (like an elderly person or a pregnant woman).
    • If you're purchasing foods like deli meat or hot dogs, store unopened packages for no longer than two weeks and store opened packages no more than three to five days.[5]
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    Avoid smoked or refrigerated seafood. A more uncommon source of Listeria is smoked and refrigerated seafood. Although this might not be a frequent part of your diet, items like lox or smoked trout can contain Listeria.[6]
    • Limit or avoid any seafood with labeling that says any of the following: smoked, kippered, nova-style, lox, or jerky. These types of seafood are the ones that would contain Listeria.
    • You will typically find this type of fish or seafood in the refrigerated section of the grocery store (many times near the seafood counter).
    • Note that canned seafood (like canned tuna or salmon) is OK to eat and will not contain Listeria bacteria since it's been processed at high temperatures where that bacteria would be killed off.
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    Be mindful of melons. Although Listeria typically is not found on or in fresh produce, there has been several outbreaks of Listeria that have stemmed from melons (like cantaloupe melon).[7] Be very careful and use proper sanitation techniques when eating melons.
    • Contamination of Listeria on melons is generally linked to unsanitary handling and storing practices on the behalf of the farmer and/or processing facility.[8] It's only the outside of a whole melon that can be contaminated; however, when you cut through a melon, you drag the bacteria from the outside of the melon into the flesh of the melon with your knife.
    • To avoid eating contaminated melons make sure you wash your hands for 20 seconds with hot soapy water before and after preparing your melon.
    • Also scrub the outside of the melon with warm soapy water using a produce brush. Dry the melon well and then cut and serve. Don't forget to wash and sanitize the produce brush after each melon or between uses.
    • Keep cut melon in the refrigerator in an airtight container for no more than seven days.

Part 2
Storing and Handling Foods Safely at Home

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    Wash your hands before eating. In addition to being mindful about the types of foods that could contain Listeria, it's also important to make sure you do not contaminate yourself with dirty hands.[9] Wash them appropriately to decrease your risk of self or cross contamination.
    • The best method of hand washing is by using soap and water. Although alcohol based cleanser do kill bacteria, soap and water has always been the most recommended by health professionals.
    • Using warm water, lather your hands and wrists well with soap. Scrub your fingers, palms and backs of your hands for at least 20 seconds (about the time it'll take you to say your ABC's).
    • Rinse well and then dry your hands using a paper towel. Do not use a dish cloth to dry your hands as there might be germs or bacteria that can recontaminate your freshly washed hands.
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    Abide by "use by" dates. Although there has been recent news suggesting you may be able to consume foods past their "use by" dates, it's not advised by health professionals. Do not consume foods that have expired as these foods may contain Listeria among other harmful bacteria.[10]
    • A "use by" date is listed on all packaged goods. It may be difficult to locate, but look on the top, bottom and sides of packaging to locate this information. This is a date recommended by the food manufacturer that signifies the last date the food will be of peak quality.
    • Regarding Listeria specifically, always follow the "use by" date on all foods, but specifically look for dates on deli meat, pre-prepared meat salads or pate, hot dogs and smoked seafood.
    • Throw out or do not consume any foods that are past the "use by" date. This is especially important to follow if you have a compromised immune system, are pregnant, are elderly or have are feeding a young child.
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    Store protein safely in the refrigerator. It's important to also store food appropriately and safely in your refrigerator to help prevent the cross contamination of foods and to help prevent the growth of Listeria bacteria. Be very mindful of where and how you store your foods.
    • Listeria is a particularly dangerous type of bacteria not only due to the severe symptoms and side effects, but also because it can grow well in cold temperatures that some refrigerators may be set at.[11]
    • To start, make sure your refrigerator is set at the correct temperature. It should be set at 40°F (4.4°C). Foods that are held above 40°F (4.4°C) for more than two hours should not be consumed.
    • Be mindful of where you place foods in the refrigerator as well. Raw meat, poultry or seafood should be stored in a sealed container on the bottom shelf of the refrigerator and underneath any fresh produce.
    • Do not store perishable foods (like milk) on the door of the refrigerator. The temperature fluctuates greatly as you open and close the door. Keep more stable items, like condiments and butter, on the door.
    • If you notice any spills (especially from meat products), clean them up immediately with a bleach-based cleaner or antiseptic-grade cleaner.
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    Avoid cross contamination while cooking. Even if you have foods that do not contain Listeria, if you mishandle them during preparation and cooking, you could contaminate the foods and yourself.[12] Be careful to make sure you practice safe handling and preparation methods.
    • To start food preparation, make sure you're using clean knives, utensils, bowls and cutting boards. If you're unsure, wash and sanitize them prior to use. Also only use one cutting board for raw meat (you may want to color code this).
    • Cook all meat to the appropriate temperatures and make sure to measure the temperature with a thermometer. This helps kill any harmful bacteria.
    • Beef should be cooked to 160°F (71.1°C), poultry should be cooked to 165°F (173.9°C), pork, ham and seafood should be cooked to 145°F (62.8°C), and all leftovers or casseroles should be heated until they reach 165°F (173.9°C).[13]
    • If you're preparing a meal with multiple dishes with different types of foods, make sure to use fresh, clean and sanitized cutlery, cutting boards and dishes with each item. For example, do not cut raw chicken with the same knife you're using to cut lettuce. You'll need to wash and sanitize the knife in between uses.
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    Eat pre-cooked or ready-to-eat foods first. When you're getting ready to prepare a meal or serve yourself a meal, think about what foods you have in your refrigerator. To avoid food waste and spoilage, try to eat the pre-cooked or leftover foods first.[14]
    • Health professionals recommend that you consume all pre-cooked or pre-made items within three to four days of purchase or from when they were originally made.
    • After this time period, you increase your risk of eating spoiled or contaminated foods which could cause foodborne illnesses like listeriosis.
    • This also goes for leftovers. These should be consumed within three to four days of when they were originally made. Store in the refrigerator in a container with an airtight lid (avoid just covering with plastic wrap or foil).

Part 3
Monitoring Any Symptoms or Side Effects

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    Track your symptoms. If you've accidentally consumed a food that was contaminated with the Listeria bacteria, you may start to exhibit a variety of symptoms. It's important to track these symptoms so you can receive the proper care.
    • Before noting exactly what symptoms you're experiencing, take a note of the time you started to notice them. Has it been 12 hours since your last meal? Did symptoms occur within 60 minutes of eating a meal or snack? Symptoms from Listeria typically don't appear until a few days have passed since eating the contaminated food.[15]
    • The first signs of a possible listeriosis infection include: fever, muscle aches, diarrhea and nausea. You may have general GI upset as well.
    • If left untreated, the Listeria bacteria can travel to your nervous system as well. Signs include: headache, stiff neck, loss of balance, confusion and convulsions.
    • If you think you've eaten food contaminated with Listeria and are experiencing symptoms, track the symptoms, their duration, their start date and severity. Provide this information to your doctor.
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    Do a food recall journal. Whenever you think you've eaten a food that has caused you to become sick, it's important to try to figure out which food could have made you sick. This way you can throw it out or warn others.
    • If you think you have listeriosis, note that symptoms typically start a few days after ingesting the contaminated food. You'll need to do a food recall for about one week in order to be accurate.
    • Write down every meal and snack that you can remember consuming for the past week. This will be difficult so asking others you ate with can help you form an accurate food recall.
    • Make sure to pay particular attention to any foods that you ate at a restaurant and foods that are known to be carries for Listeria (like deli meat, raw dairy products or hot dogs).
    • If you can, star foods that you think may have caused your illness and make sure to discard them immediately.
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    Stay hydrated. With any illness, it's important to stay properly hydrated. This is especially important if you are experiencing any GI symptoms like diarrhea. Drink adequate fluids to help prevent further symptoms or aggravation of listeriosis.
    • Even if you haven't spoken to your doctor yet, if you feel you're experiencing symptoms of listeriosis, start drinking clear, hydrating fluids.
    • Aim for a minimum of eight 8-ounce glasses (about 2 liters) of fluids daily. But when you're sick, you may need up to 13 glasses (3 liters). Stick with fluids like water, flavored water, sparkling water, and decaf coffee or tea.
    • If you cannot keep up with your fluids, you're at an increased risk to become dehydrated. If symptoms become severe enough, your doctor might give you IV fluids to restore proper hydration.[16]
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    Call your doctor. To make sure a possible Listeria infection doesn't become severe, it's important to talk to and see your doctor immediately. If you are experiencing symptoms and think you could have consumed contaminated food, call your physician immediately.
    • If you've done a food journal or recall, make sure to bring that with you to your doctors office. Let them review it to see if they can identify the food that could have caused your illness.
    • Listeria outbreaks are reported to public health officials and carefully monitored. It is important to be aware of these outbreaks in your community if you are in a high risk population. Check the Centers for Disease Control and Prevention's Foodborne Outbreak Online Database.
    • Bring a list of your symptoms and their onset. This can help your doctor determine what type of bacteria might be causing your illness as well.
    • Diagnosis of listeriosis can only be confirmed by a blood culture, not stool, like some other illnesses. Depending on the severity of the symptoms, you might be put on antibiotics as a precaution until the cultures come back negative.
    • If you're pregnant and you think you may have eaten a food contaminated with Listeria or are experiencing symptoms of listeriosis, call your OB/GYN immediately.


  • The best way to avoid coming into contact with the Listeria bacteria is to prevent cross contamination.
  • Always wash your hands and dishware thoroughly before and after using.

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Categories: Infectious Diseases