Listeria monocytogenes is a type of bacteria that causes a foodborne illness known as Listeriosis. It is responsible for an average of 300 deaths around the world each year. Listeriosis is one of the most common types of food poisoning and may be up to 40% fatal, especially in certain groups of people.
Listeria foodborne illness is difficult to predict, trace or track and even though it may lead to death, not all cases are reported. Food infected with Listeria may not smell or look different and the bacteria can survive and grow in the refrigerator, even in the freezer. Symptoms of Listeria food poisoning may begin right away or may be delayed for several months.
Because of the possible delay between eating food contaminated with Listeria and the development of symptoms, many people are unaware that food poisoning is the cause of their illness. This makes tracking outbreaks very challenging as food may also have been refrigerated or even frozen for a long period of time before eating.
What Types of Food Causes Listeriosis?
Any food that is contaminated with Listeria can cause Listeriosis but some are more common than others. Most cases of Listeria contamination occur in deli-type meats, unpasteurized dairy products and produce which came from contaminated soil or has been in contact with contaminated water.
Over the past several years, Listeria outbreaks have been responsible for hundreds of deaths. In 2011, Listeria was responsible for what was said to be the deadliest outbreak of foodborne illness in nearly 100 years the U.S. when 146 people were sickened, and 33 people died in 28 states from contaminated cantaloupe in 28 states.
Other notable outbreaks have included:
- 2017 – Soft Raw Milk Cheese
- 2016 – Frozen Vegetables
- 2015 – Soft Cheeses
- Ice Cream
- 2014 – Prepackaged Caramel Apples
- Bean Sprouts
- Dairy Products
- 2013 – Cheese
- 2012 – Ricotta Salata Cheese
Listeria outbreaks are not limited to the U.S. but occur all over the world. Just this year in 2018, over 900 people have died due to a listeria outbreak which affected bologna in South Africa and a number of people died in Australia due to cantaloupe.
In the U.S. as of September 2018, just two deaths have been reported but a number of Listeria outbreaks have occurred including:
- Turkey and cheese sandwiches
- Packaged, raw broccoli
- Nut and dried fruit mix
- Pumpkin seeds
- Packaged salad greens
- Smoked salmon spreads
- Packaged mini eclairs
- Frozen vegetables
- Frozen fruit bars
- Cream cheese
- Two separate outbreaks involving ice cream bars
- Three separate outbreaks involving cheese
Listeria outbreaks are not limited to food intended for people and have occurred in three cat food manufacturing facilities and affected dog food on seven occasions.
Symptoms of Listeria
Listeria may take longer to cause symptoms of food poisoning than many other types of foodborne illness. Due to the delay between exposure and sickness, symptoms may be interpreted as another illness. Unlike some other types of food poisoning, Listeria is usually treated with antibiotics so symptoms should be reported as soon as they occur.
The most common symptoms include:
- Muscle aches
- Nausea and less frequently, diarrhea
If the infection becomes worse or spreads to the central nervous symptoms it may cause:
- A headache
- Stiff neck
Patients whose immune system has been weakened due to illness like AIDS or cancer or who are taking immunosuppressive medications like corticosteroids may develop meningitis or central nervous system infection.
Women who are pregnant may only experience mild or flu-like symptoms but are at risk of miscarriage or stillbirth and their unborn child is at risk of infection. Symptoms of infants born with or who develop Listeriosis may be subtle and include irritability, fever, and poor feeding but may still be fatal.
Any symptoms of Listeria foodborne illness should be reported to a health official and any symptoms which occur in at-risk populations like AIDS patients, pregnant women and newborns should be treated as an emergency.
Who is most likely to get seriously ill from Listeria bacteria?
Healthy adults and children may become sickened from Listeria but most of the people who become seriously ill are from certain groups. Those at the greatest risk for Listeriosis include:
- Pregnant women
- Cancer patients or those with weakened immune systems
- People with diabetes or kidney disease
- People taking corticosteroid medications such as prednisone
- AIDS patients
People who have AIDS are 300 times more likely to become seriously ill due to Listeriosis. Pregnant women are 20 times more likely to become seriously ill and their infants may be born with Listeriosis if the mother has eaten contaminated food during pregnancy. The death rate amongst newborns can range from 25 to 50 percent.
Diagnosis and Treatment of Listeria
Though the average time for symptoms to appear in about 3 weeks, Listeriosis may develop sooner, within 1 to 3 days of exposure or may be delayed for up to 90 days after eating food contaminated with Listeria. Listeria infection is diagnosed by taking a blood or spinal fluid sample.
Listeria is usually treated with antibiotics. Pregnant women who take antibiotics may help prevent the infection from spreading to their infants.
Preventing Listeria Food Borne Illness
While Listeria may be difficult to detect, certain safety measures can help to prevent the illness. Tips for preventing Listeria exposure include:
- Wash raw vegetables before eating, even when purchased as “prewashed”
- Wash fruits before eating them, include fruits with an inedible rind or peel like cantaloupe
- Keep cooked meats separately from other foods
- Avoid products with unpasteurized milk
- Thoroughly cook meats to the appropriate temperature:
- beef, pork, lamb and fish – 145 F
- ground beef, pork or lamb – 160 F
- poultry (chicken, duck, turkey) – 165 F
- eggs – no visible liquid remains
- Wash hands and utensils for at least 20 seconds in warm soapy water after handling foods
- Eat perishable and ready-to-eat foods as soon as possible after purchase
Avoid hot dogs and deli meats unless they are heated to a temperature sufficient to “cook” the foods
Do not get water from a hot dog or lunch meat package on other foods
- Wash hands after handling deli meats or hot dogs
- Avoid soft cheeses unless labeled as pasteurized (feta, brie, blue cheese, queso blanco etc.)
- Avoid refrigerated meat and seafood spreads, and smoked seafood. Canned or shelf-stable products are acceptable as they have been heated treated or radiated to kill Listeria and other bacteria
When foodborne illnesses like Listeriosis are a result of contamination in manufacturing or restaurants, a large number of people may become ill. Treatment for Listeriosis can be costly and the infection may result in death. Commercial facilities and businesses may be considered liable for costs related to treatment and wrongful death.
Over the past several years, a number of high profile lawsuits filed by victims of Listeria contamination, have been settled. In most cases, food poisoning lawsuit settlement amounts are not disclosed but victims generally receive compensation for medical expenses, lost wages, pain, and suffering and future medical costs or for wrongful death when a victim has died.
Notable cases that have been settled include:
- 1 Blue ice cream contamination settled in Texas
- 2 cases of Dole salad contamination settled
- 23 lawsuits settled by Walmart for cantaloupe contamination
- 24 wrongful death cases settled for cantaloupe contamination
- 20 additional cantaloupe medical injury cases against grower, distributors, and restaurants settled in Colorado
People or loved ones of those who have been injured or who died due to Listeriosis or Listeria food poisoning should seek legal advice. They may be eligible for compensation.