Listeria (listeriosis): Symptoms, causes and treatments

Listeriosis is a food-borne infection caused by Listeria bacteria. The majority of people who become infected might barely notice the illness. However, those at risk can be severely affected, and mortality rates are relatively high.

Listeriosis, also called Listeria, can be a serious infection; it strikes pregnant women, newborns, the elderly, and anyone with a weakened immune system.

In this article, we will look at the symptoms, diagnosis, and treatment of listeriosis. We will also discuss how the bacteria works, the best ways to avoid infection, and recent research into preventing the disease.

Fast facts on listeriosis

Here are some key points about listeriosis. More detail and supporting information is in the main article.

Listeriosis is an infection caused by Listeria monocytogenes

An estimated 260 Americans die of listeriosis yearly.

Only immunosuppressed individuals and pregnant women are at risk of a serious case of listeriosis.

Listeriosis can lead to septicemia or meningitis.

Pregnant women are 10 times more likely to be infected with Listeria than the general population.

What is it?

Listeriosis is an infection caused by Listeria bacteria, named after Joseph Lister, the surgeon and pioneer of antiseptic surgery. There are 10 distinct species of Listeria; the variant that most commonly impacts humans is Listeria monocytogenes.

Listeria is responsible for around 1,600 illnesses and 260 deaths in the United States yearly, exceeding the fatality rates of Salmonella and Clostridium botulinum. This rate of infection has remained relatively stable over recent years.

Normally caused by eating contaminated food, around 20-30 percent of listeriosis cases are fatal.

Woman experiencing fever holding her head
Symptoms of listeria include fever.

The initial symptoms of listeriosis might not become apparent for some time; the incubation period is variable and can be anything from 11-70 days after consuming food with Listeria.

The following symptoms of Listeria infection are likely to last 1-3 days:

muscle aches


flu-like symptoms



For many people, a Listeria infection will pass unnoticed. However, in some individuals, the infection will spread to the nervous system where symptoms might include:



stiff neck

tremors and convulsions

loss of balance

In susceptible individuals, listeriosis can lead to a serious blood infection (septicemia) or inflammation of the membranes around the brain (meningitis).

If the listeriosis infection spreads to the brain, the outcomes can be severe and may include:

Cranial nerve palsies: Paralysis and tremors.

Encephalitis: Inflammation of the brain.

Meningitis: Inflammation of the membranes covering the brain and spinal cord.

Meningoencephalitis: A combination of meningitis and encephalitis.

Cerebral abscesses: Localized pus build-up within the brain.

Symptoms during pregnancy or for newborn infants

Pregnant women are 10 times more likely to develop listeriosis than the general population. The incidence of listeriosis during pregnancy is 12 per 100,000, compared with 0.7 per 100,000 in the general population.

While a mother with a Listeria infection may not show any outward symptoms, an unborn child might be severely affected.

Listeriosis can result in miscarriage or premature birth. There is a possibility that a newborn might suffer a life-threatening infection in the days and weeks after birth.

The symptoms in a newborn child can be subtle but may include:

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