Are Listeria Outbreaks Lethal?

Are Listeria Outbreaks Lethal?

Listeriosis is a serious foodborne illness which is caused by bacterium Listeria monocytogenes. It is caused by consuming food contaminated with listeria bacterium.

Where listeria bacterium can be found?

Listeria monocytogenes causes listeriosis. This bacterium can be found in the soil, water, vegetation and in animal feces. Listeria can contaminate various products, like dairy, meat, and seafood. Once the food production facility gets contaminated with Listeria, it becomes difficult to cope with it.

The Incubation Period of Listeria

Normally, the incubation time period of listeria is between 3-30 days. However, it may vary for every case.

Symptoms of Listeria infection

According to the CDC, these infections can have the following symptoms:

  • Mild flu-like complaints
  • Fever
  • Headache
  • Nausea
  • vomiting
  • Diarrhea
  • Muscle aches

If the listeria infection spreads to the nervous system. It can cause the following symptoms:

  • State of confusion
  • Stiff neck
  • convulsions
  • loss of balance
  • Disorientation

Listeria Outbreaks

Potentially lethal illness with Listeria is rare but, in some cases, it can be lethal.

According to CDC, every year listeriosis affects 1,600 people, out of which about 260 dies.

Is Listeriosis dangerous?

Typically, Listeria isn’t dangerous for most people but can affect some people. Following people are likely to get affected:

  • Sicken pregnant women
  • Newborns
  • People aged 65 or older
  • People having a weak immune system
  • Organ transplant patients, who are taking medicines to prevent organ rejection
  • People suffering from the following conditions:


Renal disease

Liver disease


Autoimmune disease


Dr. Amesh Adalja (Scholar at the Johns Hopkins Center for Health Security in Baltimore) said, that the bacteria mainly cause symptoms in people with weak immune systems or people having low ability to fight infections as mentioned above.

CDC said that people with low immunity should be careful about the consumption of cold cuts, lunch meats, hot dogs and other deli meats. These foods should be used after heating to a temperature of 165 degrees Fahrenheit (74 degrees Celsius). These people should avoid the consumption of soft cheeses unless these are labeled to be made with pasteurized milk.

Complications Associated with Listeriosis

  • Central nervous system

Listeria can get into the central nervous system which can cause serious complications. Once Listeria gets inside the central nervous system, it can cause infection in the membranes surrounding the brain and spinal cord (known as”meningitis” ). It can also cause encephalitis. Both complications can be lethal.

Dr. Adalja said that

“The fact that Listeria has this ability to get into the central nervous system makes it deadlier,”

” Infection in the central nervous system is much more serious than the one restricted to the GI [gastrointestinal] track”

  • Pregnant Women

According to the American College of Obstetricians and Gynecologists, pregnant women are 10 times more at risk of getting infected with Listeria than the people of the general population.

In the case of pregnancy, Listeria infections can affect both the woman and fetus. American College of Obstetricians and Gynecologists says that these infections can lead to stillbirth, miscarriage or preterm labor.

Therefore, pregnant women should avoid the use of food products that are more likely to contain Listeria bacteria. Unpasteurized milk and foods prepared with unpasteurized milk, including soft cheeses can be a source of listeria infection.

Reported Outbreaks

Outbreaks of listeria were reported in the following countries:

Pennsylvania, Michigan, New York, and New Jersey

The recent Listeria outbreak occurred on 17th April of this year. According to the Centers for Disease Control and Prevention, the outbreak affected a total of eight people in four states Pennsylvania, Michigan, New York, and New Jersey. All eight patients were hospitalized, and one died in Michigan. Patients were reported to have listeria infection, after the consumption of deli meats and cheeses.

Previously, this infection was also reported in November 2016.

California Apple Processing Plant

Strains of listeria bacteria found inside a California apple processing plant are thought to be the same ones associated with an outbreak that killed seven people and sickened dozens of others last year

This year, Strains of listeria are found inside the apple processing plant California. These strains are the same ones which caused an outbreak last year. The Food and Drug Administration (FDA) confirmed the occurrence of two strains of Listeria monocytogenes inside the apple processing plant California.

The Centers for Disease Control and Prevention mentioned that majority of the people have listeriosis after the consumption of packaged, caramel-coated apples. During this outbreak, 32 people were sickened while 7 were dead. Leonard Bidart, the company’s president, said that,

“As a family-owned grower operating in California since the 1930s, we place safety at the forefront of everything we do. Our hearts go out to all who have been impacted by the apple-related listeriosis outbreak”

United States

Previously, World’s largest listeriosis outbreaks occurred in united states in 2011. United States outbreak was traced by Public health officials. It occurred because of cantaloupes from Jensen Farms in Colorado. In this outbreak, 147 people were affected, and 33 people died.


One of the largest Listeria outbreaks occurred in Italy in 1997. It occurred because of tuna salad and cold corn. It affected more than 1,500 people, most of them were children


Listeria outbreaks also affected Canada. It resulted in the deaths of 22 mostly elderly Canadians. This Listeria outbreak was caused by deli meats from Canada’s Maple Leaf Foods.

South Africa

On January 18, 2018, the deadly and record-setting listeriosis outbreak occurred in South Africa.

During this outbreak, the country’s National Institute for Communicable Diseases (NICD) confirmed 67 deaths caused by listeriosis. On Dec. 5, 2017, the largest ever listeriosis outbreak was reported in South African. During this outbreak, 748 cases were reported and out of these, 9% died.

The South African government suspects that a food source is responsible for this outbreak.

Following food testing labs of South Africa investigated this outbreak.

  • South African Meat Processors Association
  • The National Laboratory Association
  • South African Milk Processors Association
  • Milk South Africa, Consumer Goods Council

Food Products Associated with Listeriosis

In the past, various food products caused Listeriosis which are the following:

In 2019

  • Cheeses
  • Deli- Sliced Meat
In 2018
  • Deli Ham
  • Pork products
In 2017
  • Vulto creamery Soft Raw Milk Cheese
In 2016
  • Frozen vegetables
  • Packaged salad
  • Raw Milk
In 2015
  • ice-cream
  • Soft Cheeses
In 2014
  • Dairy products
  • Bean sprouts
  • Cheese
  • Prepackaged Caramel Apples
In 2013
  • Cheese
In 2012
  • Ricotta Salata cheese
In 2011
  • Cantaloupes


Following precautions must be taken to prevent listeriosis outbreak:

  • Wash hands before and during the preparation of food.
  • keep raw meat, seafood, and poultry separate from fruits, vegetables, and cooked foods.
  • Properly cook meat, seafood, and eggs.
  • Don’t Consume unpasteurized or raw milk.
  • Products made from unpasteurized milk should also be avoided.



Hilary Jensen

Hilary is a Food Science and Nutrition graduate with specialization in diet planning and weight loss. She enjoys reading and writing on Food, Nutrition, Diet, Weight Loss, and General Health.

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