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Frequently Asked
Questions
Listeriosis, a serious infection caused by eating
food contaminated with the bacterium Listeria
monocytogenes, has recently been recognized as an important
public health problem in the United States. The disease affects
primarily pregnant women, newborns, and adults with weakened
immune systems. It can be avoided by following a few simple
recommendations.
What are the
symptoms of listeriosis?
A person with
listeriosis has fever, muscle aches, and sometimes gastrintestinal
symptoms such as nausea or diarrhea. If infection spreads to the
nervous system, symptoms such as headache, stiff neck, confusion,
loss of balance, or convulsions can occur.
Infected pregnant women may experience only a mild, flu-like
illness; however, infections during pregnancy can lead to
miscarraige or stillbirth, premature delivery, or infection of the
newborn.
How great is the
risk for listeriosis?
In the United
States, an estimated 2,500 persons become seriously ill with
listeriosis each year. Of these, 500 die. At increased risk are:
- Pregnant
women - They are about 20 times more likely than other
healthy adults to get listeriosis. About one-third of
listeriosis cases happen during pregnancy.
- Newborns - Newborns rather than the pregnant women
themselves suffer the serious effects of infection in pregnancy.
- Persons with weakened immune systems
- Persons with cancer, diabetes, or kidney disease
- Persons with AIDS - They are almost 300 times more likely to
get listeriosis than people with normal immune systems.
- Persons who take glucocorticosteroid medications
- The elderly
Healthy adults and children occasionally get infected with
Listeria, but they rarely become seriously ill.

How does
Listeria get into
food?
Listeria monocytogenes
is found in soil and water. Vegetables can become contaminated
from the soil or from manure used as fertilizer. Animals can
carry the bacterium without appearing ill and can contaminate
foods of animal origin such as meats and dairy products. The
bacterium has been found in a variety of raw foods, such as
uncooked meats and vegetables, as well as in processed foods that
become contaminated after processing, such as soft cheeses and
cold cuts at the deli counter. Unpasteurized (raw) milk or foods
made from unpasteurized milk may contain the bacterium.
Listeria is killed by pasteurization and cooking;
however, in certain ready-to-eat foods such as hot dogs and deli
meats, contamination may occur after cooking but before
packaging.

How do you get
listeriosis?
You get listeriosis by
eating food contaminated with Listeria. Babies can be
born with listeriosis if their mothers eat contaminated food
during pregnancy. Although healthy persons may consume
contaminated foods without becoming ill, those at increased risk
for infection can probably get listeriosis after eating food
contaminated with even a few bacteria. Persons at risk can prevent
Listeria infection by avoiding certain high-risk foods
and by handling food properly.

Can listeriosis
be prevented?
The general guidelines
recommended for the prevention of listeriosis are similar to those
used to help prevent other foodborne illnesses, such as
salmonellosis.
How can you
reduce your risk for
listeriosis?
General recommendations:
- Thoroughly cook raw food from animal sources, such as beef,
pork, or poultry.
- Wash raw vegetables thoroughly before eating.
- Keep uncooked meats separate from vegetables and from cooked
foods and ready-to-eat foods.
- Avoid unpasteurized (raw) milk or foods made from
unpasteurized milk.
- Wash hands, knives, and cutting boards after handling
uncooked foods.
- Consume perishable and ready-to-eat foods as soon as
possible.
Recommendations for persons at high risk, such as pregnant
women and persons with weakened immune systems, in addition to the
recommendations listed above:
- Do not eat hot dogs, luncheon meats, or deli meats, unless
they are reheated until steaming hot.
- Avoid getting fluid from hot dog packages on other foods,
utensils, and food preparation surfaces, and wash hands after
handling hot dogs, luncheon meats, and deli meats.
- Do not eat soft cheeses such as feta, Brie, and Camembert,
blue-veined cheeses, or Mexican-style cheeses such as queso
blanco, queso fresco, and Panela, unless they have labels that
clearly state they are made from pastuerized milk.
- Do not eat refrigerated pâtés or meat spreads. Canned or
shelf-stable pâtés and meat spreads may be eaten.
- Do not eat refrigerated smoked seafood, unless it is
contained in acooked dish, such as a casserole. Refrigerated
smoked seafood, such as salmon, trout, whitefish, cod, tuna or
mackerel, is most often labeled as "nova-style," "lox,"
"kippered," "smoked," or "jerky." The fish is found in the
refrigerator section or sold at deli counters of grocery stores
and delicatessens. Canned or shelf-stable smoked seafood may be
eaten.

How do you know
if you have listeriosis?
There is no
routine screening test for susceptibility to listeriosis during
pregnancy, as there is for rubella and some other congenital
infections. If you have symptoms such as fever or stiff neck,
consult your doctor. A blood or spinal fluid test (to cultivate
the bacteria) will show if you have listeriosis. During pregnancy,
a blood test is the most reliable way to find out if your symptoms
are due to listeriosis.

What should you do
if you've eaten a food recalled because of Listeria
contamination?
The risk of an
individual person developing Listeria infection after
consumption of a contaminated product is very small. If you have
eaten a contaminated product and do not have any symptoms, we do
not recommend that you have any tests or treatment, even if you
are in a high-risk group. However, if you are in a high-risk
group, have eaten the contaminated product, and within 2 months
become ill with fever or signs of serious illness, you should
contact your physician and inform him or her about this
exposure.

Can listeriosis be
treated?
When infection occurs during
pregnancy, antibiotics given promptly to the pregnant woman can
often prevent infection of the fetus or newborn. Babies with
listeriosis receive the same antibiotics as adults, although a
combination of antibiotics is often used until physicians are
certain of the diagnosis. Even with prompt treatment, some
infections result in death. This is particularly likely in the
elderly and in persons with other serious medical problems.

What is the
government doing about
listeriosis?
Government agencies and
the food industry have taken steps to reduce contamination of food
by the Listeria bacterium. The Food and Drug Administration and
the U. S. Department of
Agriculture monitor food regularly. When a processed food is
found to be contaminated, food monitoring and plant inspection are
intensified, and if necessary, the implicated food is recalled.
The National Center
for Infectious Diseases (NCID) is studying listeriosis in
several states to help measure the impact of prevention activities
and recognize trends in disease occurrence. NCID also assists
local health departments in investigating outbreaks. Early
detection and reporting of outbreaks of listeriosis to local and
state health departments can help identify sources of infection
and prevent more cases of the disease.

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