Listeriosis
(Listeria Infection)
In this condition factsheet:
The Facts on Listeriosis
Listeriosis is a foodborne illness. It most commonly affects newborns, people with weakened immune systems, seniors, and pregnant women. Pregnant women are at particular risk of having listeriosis, as they are 20 times more likely to acquire the disease than other healthy adults.
Cases of listeriosis are usually infrequent, although there have been several known outbreaks in the past. Listeriosis is a rare disease but it is very serious since it is more likely to be fatal in severe cases, compared to other bacteria that cause food poisoning.
Causes of Listeriosis
Listeriosis is caused by infection with the bacterium Listeria monocytogenes. The bacterium is found in various places in the environment – in animal feed, animal and human stool, plants, and soil. Listeria infection occurs by eating food contaminated by the bacteria. Contamination can occur at any point in the farming, distribution, and food preparation process.
Listeria is different from other bacteria that cause food poisoning because it can survive and continue to grow even when in the refrigerator. Foods contaminated with listeria look, smell, and taste normal. Listeria can be killed by proper cooking methods.
Types of food commonly contaminated by listeria include dairy products, fish, meat, and vegetables.
Symptoms and Complications of Listeriosis
Not everyone who is infected with listeria will develop listeriosis. Infants, people older than 50 years old (and especially over 65), or people with an impaired or weakened immune system are most likely to be affected. Symptoms of the disease may appear suddenly, as soon as 1 day after or up to 90 days after eating food contaminated with listeria.
Generally, milder forms of listeriosis will cause symptoms much sooner than more serious forms of the disease.
Symptoms of listeriosis include:
- constipation
- cramps
- diarrhea
- headache
- mild flu-like illness (e.g., chills, fatigue, muscle and joint pain)
- nausea
- persistent fever
- vomiting
Rarely, very severe forms such as meningoencephalitis (an infection of the brain and the surrounding tissues) or bacteremia (where the bacteria are present in the blood) may follow.
Listeriosis can be particularly harmful during pregnancy. A mother who is infected during the first 3 months of pregnancy may miscarry. Listeria can also be passed from a pregnant woman to her unborn baby. Acute illness, premature birth, and stillbirth are possible if the mother is infected later in pregnancy. Newborns may also have low birth weight, meningitis, or overwhelming sepsis.
