What is Listeriosis
Listeriosis is a serious infection Which is
caused by eating food contaminated with the
bacterium Listeria monocytogenes.
It has recently been recognized as an
important public health problem in
Canada and the United States.
The disease affects primarily persons of
advanced age, pregnant women, newborns, and
adults with weakened immune systems. However,
persons without these risk factors can also
rarely be affected. The risk may be
reduced by following a few simple
recommendations.
In veterinary medicine, however, listeriosis
can be a quite common condition in some farm
outbreaks. It can also be found in wild
animals.
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How great is the risk for
listeriosis?
In the United States, an
estimated that over 2,000 persons become
seriously ill with listeriosis each year.
Of these, appox. 500 die.
People with 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.
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How
does Listeria Bacteria get into
food?
Listeria
monocytogenes is found in water and
soil.
Vegetables can become
contaminated from the soil and 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 bacteria 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 also
contain the bacteria.
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.
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How do
you contract 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.
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How can you reduce your risk for
listeriosis?
Recommendations:
Thoroughly cook raw food from animal
sources, such as beef, pork, or poultry.
Thoroughly wash raw vegetables 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 people at high risk, such as pregnant
women and people with low or weak 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 consume 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 consume refrigerated pates
or meat spreads. Canned or
shelf-stable pates and meat spreads may be
eaten.
Do not eat refrigerated smoked seafood,
unless it is contained in a cooked 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.
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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 salmonella.
In addition, there are specific recommendations
for persons at high risk for listeriosis.
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What are the symptoms?
- Symptoms include: flu-like symptoms,
nausea, vomiting, cramps, diarrhea,
headache, constipation and persistent
fever.
- Symptoms usually appear within 2 to 30
days and sometimes up to 70 days after
consuming contaminated food.
- The very young, elderly or people
with poor immune systems are the most
at risk.
- Flu-like symptoms may be followed by a
brain or blood infection, either of which
can result in death.
- A woman who develops listeriosis during
the first three months of
pregnancy could miscarry. If she
develops listeriosis later in the
pregnancy, her baby may be stillborn or
acutely ill.
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How can you protect yourself
and your family?
- Keep foods out of the temperature
danger zone (between 4°C and
60°C or
40°F
and 140°F). Keep the
refrigerator at 4°C (40°F) or colder.
Refrigerate food promptly.
- Thoroughly cook or boil foods such as
hot dogs and poultry products until they
are steaming hot.
- Avoid raw, unpasteurised milk or foods
made from raw milk or cheese.
- Buy only as much product as will
be consumed in 1 to 2 days.
- Thoroughly wash raw vegetables
before eating.
- Always wash your hands before, during
and after handling any type of food.
Especially raw meat and poultry.
- Clean all utensils, such as, cutting
boards and work surfaces with a mild bleach
solution (5 ml/1
tsp.
bleach per 750 ml/3 cups water)
before and after using.
- Separate utensils for raw and cooked
foods.
- Follow “use by” dates especially on
packaged goods with a long shelf life.
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How do
you know if you have
listeriosis?
At the moment there is no
routine screening test for listeriosis
during pregnancy, as there is for rubella
and some other congenital infections.
If you have symptoms such as a
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.
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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.
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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
Coordinating Center for
Infectious Diseases (CCID) is
studying listeriosis in several states to help
measure the impact of prevention activities and
recognize trends in disease occurrence. CCID
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.
In Canada:
For more information on
foodborne illness and safe food handling
practices, visit the Canadian Food
Inspection Agency website at www.inspection.gc.ca
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