Listeria monocytogenes (commonly called Listeria) can cause a rare but serious disease called listeriosis, especially among pregnant women, the elderly or individuals with a weakened immune system. Listeria is a type of bacterium often found in food and elsewhere in nature.In serious cases it can lead to brain infection and even death.



Listeria is widespread in the environment and is found in soil, vegetation, water, sewage, silage and in the feces of humans and animals. Animals and humans can carry the bacterium without knowing it. Plants and vegetables can become contaminated with Listeria from the soil, water and manure-based fertilizers. Farm animals that appear healthy may also carry Listeria and contaminate foods such as meats and dairy products.

Unlike most bacteria, Listeria can survive and sometimes grow on foods being stored in the refrigerator. Moreover, foods that are contaminated with this bacterium look, smell and taste normal. Listeria can be killed by proper cooking procedures.

Listeria is more likely to cause death than other bacteria that cause food poisoning. In fact, 20 to 30 percent of foodborne listeriosis infections in high-risk individuals may be fatal. However, it should be noted that listeriosis is a relatively rare disease in most developed countries.

Many people may be carriers of Listeria, but few will actually develop listeriosis. Those who do will likely become ill from eating food contaminated with the bacteria, often seen as an outbreak of what people would call 'food poisoning'. Symptoms may start suddenly and include:

Vomiting;

Nausea;

Cramps;

Diarrhea;

Severe Headache;

Constipation; or

Persistent fever.

In some instances, these symptoms may be followed by meningitis encephalitis, an infection of the brain or its surrounding tissues and/or septicemia or blood poisoning, either of which can result in death. The mild form of foodborne listeriosis usually begins about one day after eating heavily contaminated food. For the more serious form of the disease, the incubation period is generally much longer - up to 70 days after exposure.

Those who are at the highest risk of serious illness include pregnant women and their unborn/newborn children. Pregnant women are about 20 times more likely to get listeriosis than other healthy adults. If a pregnant woman develops listeriosis during the first three months of her pregnancy, she may miscarry. Up to two weeks before a miscarriage, pregnant women may experience a mild flu-like illness with chills, fatigue, headache as well as muscular and joint pain. Listeriosis later on in the pregnancy can result in a stillbirth or the birth of an acutely-ill child.

The risk of listeriosis increases with age as the elderly and people with weakened immune systems, such as those undergoing chemotherapy, transplant patients, those with HIV, diabetics and alcoholics are most at

risk. The highest risk group includes those whose immune systems are highly compromised, such as bone marrow transplant patients, blood-borne cancer patients and those with full-blown AIDS.

People with AIDS are at least 300 times more likely to get listeriosis than those with a normal immune system. The disease can be effectively treated with antibiotics, but early diagnosis can be critical to the success of the treatment, especially for those at high risk. At the moment, there is no vaccine to prevent listeriosis.