Disease Fact Sheet Series:
What is Listeriosis?
Listeriosis is a serious infection usually associated with eating food
contaminated with the bacterium Listeria monocytogenes.
Where are these bacteria found? How does it get into
food?
Listeria monocytogenes can frequently be found in the
environment, especially in water, mud and silage. It may also be present
in the intestines of humans and animals, unpasteurized milk, soil, leafy
vegetables and food processing environments. Animals can carry the
bacteria without appearing ill.
Outbreaks of listeriosis have been associated with
ingestion of unpasteurized milk and dairy products made from unpasteurized
or inadequately pasteurized milk. Animals carrying the bacteria can be the
source of contamination of these food products. If these food products are
not cooked properly or pasteurized, the bacteria can cause illness when a
person eats the contaminated product. Outbreaks have also been associated
with raw vegetables or products made with raw vegetables, including fresh
vegetables fertilized with untreated manure. The bacteria is not passed
from person to person.
Who gets listeriosis?
Anyone can get Listeriosis, but the greatest risk for disease is among
the elderly, pregnant women, or those with weakened immune systems.
Pregnant women may only experience mild illness but can pass the infection
on to their fetuses.
What are the symptoms?
In normal adults, Listeriosis causes a "flu-like" illness
including the sudden onset of fever, chills, headache, backache, and
occasionally abdominal pain, nausea and diarrhea. Serious complications
such as convulsions, confusion and coma can occur. Newborns may experience
respiratory distress (trouble breathing), irritability, refusal to drink,
and vomiting. More serious complications in newborn babies can include
meningitis (inflammation of the tissues around the brain and spine) and
septicemia (blood poisoning).
During pregnancy the mother may only experience mild,
"flu-like " symptoms but the infection can lead to infection of
the newborn, premature delivery and stillbirths.
How long after exposure do symptoms occur?
During outbreaks, cases have occurred between 3-70 days after eating a
contaminated product. The average time between exposure and illness is
estimated to be approximately three weeks.
How is Listeriosis diagnosed?
The diagnosis is confirmed by finding the bacteria in the spinal
fluid, blood and other sites of infection.
How is Listeriosis treated?
Specific antibiotics can be prescribed by a physician for the
treatment of Listeriosis. Antibiotics given to pregnant women with
Listeriosis can often prevent the fetus from being infected.
What can be done to prevent Listeriosis?
Eat only meats that have been properly cooked. Avoid deli meats,
processed meats such as bologna or uncooked hotdogs. Wash fresh vegetables
thoroughly and avoid organic vegetables fertilized with
"untreated" manure. Avoid unpasteurized (raw) milk and cheese or
other dairy products made from unpasteurized milk. Pregnant women and
other groups at risk are advised to follow "keep refrigerated"
labels and observe "sell by" and "use by" dates on
processed products. Women who develop "flu-like" symptoms during
pregnancy should see their physician.
Avoid contact with potentially infected livestock and especially
infected animal material such as aborted fetuses.
For more information, contact your
Local
Public Health Department
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Last Revised: November 04, 2008
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