Listeria is a genus of bacteria most species of which, if consumed, can make people seriously ill. It can be found in soft cheeses made from unpasteurized milk, raw meat, unwashed vegetables, deli meats, and hot dogs or sausages that are not fully heated, even if they are fully cooked before packaging. In most cases, slight exposure will not result in symptoms; however, those with lower immune systems are at greater risk for contraction.
A Listeria infection may present with fever, soreness of the neck, and vomiting or diarrhea. Complicated forms can lead to the development of both encephalitis and certain forms of meningitis. Women who are pregnant who contract illness from this bacteria can have sudden stillbirths. Further, pregnant women are about 20 times more likely than the rest of the general population to get listeriosis. If miscarriage or stillbirth does not result, newborns can be born with Listeria infections, which can lead to higher rates of infant mortality. Since pregnant women are particularly prone to this bacteria, and the effects can be quite devastating, women who are pregnant or nursing newborns should report any symptoms of gastrointestinal illness accompanied by headaches or a sore neck and fever.
Others at risk for complications from Listeria ingestion include those with HIV, those who have received organ transplants, those with diabetes, newborns, and the elderly. It is most important that people in these higher risk groups observe some precautionary procedures that can help reduce the risk of contraction.
Those at risk should avoid raw milk or cheese made with raw milk. Deli meats should be avoided as well. If eating hot dogs or sausages, these should be fully cooked since heating destroys the bacteria cells. Any raw vegetables or fruit should be thoroughly washed. Raw meat should be avoided completely.
Recent studies show that premade salads, with lettuce, dressing and other additions that one compiles at home have also shown a higher incidence of Listeria. Though these salads may be convenient, the US Centers for Disease Control (CDC) now recommends that lettuce and other vegetables be washed, even if the label advertises these products as prewashed.
The presence of Listeria infection can be confirmed by blood test. Physicians usually ask for a fecal sample as well. When diagnosed, this bacteria is treated with antibiotics which will kill the cells and generally prevent the complications of meningitis, encephalitis and stillbirth.
In the US, when cases of Listeria are reported to a physician, the physician reports this information to both the Food and Drug Administration (FDA) and the CDC. This is helpful to identify the source of infection and warn others regarding the possibility of exposure to the bacteria. If a person is aware that he or she has been exposed to Listeria, he or she should keep in mind that symptoms can occur anytime within two months of exposure. It is advisable to see a physician and mention exposure.
Most people who contract this bacteria will not go on to have future complications. Additionally, only a small number of people are infected each year. Should someone feel he or she is experiencing symptoms common to Listeria infections, however, it is prudent to see a physician immediately, as treatment is simply a course of antibiotics.
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.
Not everyone who is infected with listeria will develop listeriosis. Infants, seniors, 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 and 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:
cramps
diarrhea
headache
mild flu-like illness (e.g., chills, fatigue, muscle and joint pain)
nausea
persistent fever
vomiting
Rarely, meningoencephalitis (an infection of the brain and the surrounding tissues) or septicemia (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. Acute illness, premature birth, and stillbirth of the newborn are possible if the mother is infected later in pregnancy. Newborns may also have low birth weight, meningitis, and various other complications.
Treatment of listeria infection varies, depending on the severity of the signs and symptoms. Most people with mild symptoms require no treatment. More serious infections can be treated with antibiotics. During pregnancy, prompt antibiotic treatment may help keep the infection from affecting the baby (and always consult a doctor before use). Newborns who have a listeria infection may receive a combination of antibiotics.