Listeriosis: Overview


Listeriosis is a bacterial infection most commonly caused by Listeria monocytogenes.

March 20, 2018

Listeriosis is a bacterial infection most commonly caused by Listeria monocytogenes. Listeria primarily causes infections of the central nervous system such as meningitis, meningoencephalitis, brain abscess, cerebritis. It can also cause bacteremia in those who are immunocompromised such as pregnant women, newborns and the elderly. Gastroenteritis or food poisoning caused by eating contaminated foods in healthy persons who have been severely infected.
Babies can be born with listeriosis if their mothers eat contaminated food during pregnancy. In pregnant women, the infection can result in miscarriage, premature delivery, serious infection of the newborn, or even stillbirth.
Listeria is primarily transmitted through contaminated food products, after which the organism penetrates the intestinal tract to cause systemic infections. Listeria bacteria are widespread throughout the world and are often associated with farm animals that may show no signs of infection. There is no direct transfer of Listeria from human to human except for pregnant women and their fetus or newborn.
The bacteria can penetrate human cells and can multiply inside them. People who are immunocompromised are less able to control the spread of these organisms into the blood or into other cells. In most of the cases the bacteria are not contagious from person to person except in case of a pregnant woman who can transfer the bacteria to the fetus or the newborn. 
In pregnant women, the infection can result in miscarriage, premature delivery, serious infection of the newborn, or even stillbirth.
Localized skin infections may occur in very rare cases especially in people who handle animals that are infected with Listeria. These skin infections rarely lead to further complications such as brain infection.
Usually a person with listeriosis has fever and muscle aches, diarrhea or other gastrointestinal symptoms. Almost in all the cases the bacteria spreads from intestines to blood stream or other body sites. Listeria infections may last about one week to about six weeks, depending upon the severity of the infection and the disease can occur even after two months of eating contaminated food. Most people who are infected have few or no symptoms. 
People who are immunocompromised such as pregnant females and their fetus or newborn, cancer patients, AIDS patients, people with diabetes, and alcoholics are at higher risk for getting the disease and some are more likely to have more severe disease.
Listeriosis is usually diagnosed when a person was found to be associated with an outbreak of Listeria-contaminated food or fluid or associated with the known source of listeriosis outbreak. The diagnosis is confirmed when Listeria bacteria are isolated from blood, cerebrospinal fluid, or other body fluid of the patient. A healthy person can clear the infection and require no treatment, where as people with risk factors should be treated quickly with IV antibiotics. Foods that are not cooked or fluids that are not treated or pasteurized are frequently the sources of infection. If any individual consume this type of food they will be exposed to Listeria bacteria. During pregnancy, women can transmit Listeria organisms to their fetus or to their newborn. Listeriosis is not contagious from person to person except in pregnancy. Mostly the disease is transmitted to humans by contaminated food or fluids. 
Cooking foods, treating or pasteurizing fluids, and avoiding food and fluids that may be contaminated with animal or human waste may prevent infection.