An uncommon infection transmitted through contaminated food
The bacterium that causes listeriosis, Listeria monocytogenes, is widespread in the soil and is present in most animal species. It can pass to humans through food products, particularly soft cheeses, milk, meat pâtés, and prepackaged salads. The risk of listeriosis is increased by incorrect storage of these foods. The bacteria multiply in the intestines and may spread in the blood (see Septicaemia) and affect other organs.
The symptoms of listeriosis vary from one person to another. The infection often goes unnoticed in healthy adults, although some people may develop flu-like symptoms such as fever, sore throat, headache, and aching muscles.
In elderly people and people with reduced immunity, such as those with HIV infection (see HIV infection and AIDS) or those taking immunosuppressant drugs, listeriosis can lead to meningitis, a potentially fatal inflammation of the membranes covering the brain. In pregnant women, infection can pass to the fetus, causing miscarriage, the birth of a baby infected with the bacteria, or stillbirth.
Listeriosis is usually diagnosed from a blood test. In otherwise healthy people, mild listeriosis clears up without treatment in a few days. People with serious infection, especially during pregnancy, need urgent treatment in hospital with intravenous antibiotics.
Hygienic handling and storage of food reduces the risk of listeriosis (see Home safety and health).
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.