Updated: 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.
Listeriosis primarily affects older adults, persons with weakened immune systems, pregnant women, and newborns. People without these risk factors can also be affected which is very rare. 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. When symptoms of Listeria infection are present, the symptoms can be different as per the infected person:
Pregnant women typically experience only a mild, flu-like illness. However, infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn. The bacteria will not get transmitted to newborns by breastfeeding in humans . However, the organisms are transferred in breast milk of other mammalian species.
Symptoms can include fever, muscle aches, headache, stiff neck, confusion, loss of balance, meningitis, convulsions and even death. Fever and headache can be mild to severe depending on the severity of infection. It could be encephalitis if stiff neck, headache, and fever is present. If the infection has spread to the brain, loss of balance problems and seizures (convulsions) may develop. Brain abscesses may also occur and cause similar symptoms.
People who were previously healthy but are infected by Listeria can develop a non-invasive illness. In this case the bacteria have not spread into their blood stream or other body sites. Symptoms may include nausea, diarrhea and fever. You may experience stomach discomfort and the sensation of wanting to vomit. Some individuals may also experience fatigue and a decrease or loss of appetite. However these symptoms usually last up to one week and may get resolved without any treatment.
Very rarely you may experience localized skin infections. This can occur especially in people who handle animals that are infected with Listeria. These skin infections rarely lead to further complications such as brain infection.