Listeriosis (Listeria monocytogenes Infection)

  • Medical Author:
    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Quick GuideBacterial Infections 101: Types, Symptoms, and Treatments

Bacterial Infections 101: Types, Symptoms, and Treatments

What is listeriosis? What causes listeriosis?

Listeriosis is an infection caused by a gram stain-positive motile bacterium named Listeria monocytogenes. The foodborne illness produces fever, muscle aches, and, in many people, diarrhea. Severe infections can cause headaches, meningitis, convulsions, and death. Most healthy people exposed to the bacteria have minor or no symptoms, but a few people, especially the elderly, pregnant females and their fetus, newborns, and anyone with a compromised immune system are especially susceptible to these organisms. Listeria bacteria are widespread throughout the world and are often associated with farm animals that may show no signs of infection. Research shows that many animals are uninfected carriers, and they suggest that some humans carry these organisms as part of their bowel flora. Except for pregnant women and their fetus or newborn, there is no direct transfer of Listeria from human to human.

The organisms (Listeria monocytogenes) that cause listeriosis have probably been infecting humans for centuries. Listeria was first isolated from an infected WWI soldier in 1918 and had many different names until 1940, when the genus and species names were firmly established. However, the bacteria were first recognized as a food-borne (food poisoning) pathogen in 1979. The bacteria can penetrate human cells and can multiply inside them. People with altered or impaired immune systems have cells that are less able to control the spread of these organisms into the blood or into other cells. In 2010, a known species, Listeria ivanovii, thought only to infect cattle, was found to infect humans so there are two Listeria species that can infect humans.

Outbreaks of listeriosis can occur with some frequency. For example, in 2017, soft raw milk cheese was a source of an outbreak (Vulto Creamery). In this outbreak, eight people were infected and two died. Other recalls of products in 2017 include 3 tons of cheese for possible Listeria contamination (La Nica Products INC.), macadamia nuts (Simple Truth brand), Ava's Organic Cashews, and Queso Fresco cheese, for the same problem.

Medically Reviewed by a Doctor on 6/6/2017

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