Disease
Fact Sheet Series:
What
is amebiasis?
Amebiasis
is an intestinal illness caused by a microscopic parasitic amoeba called Entamoeba
histolytica. Wisconsin averages about 10-15 cases per year.
Who
gets amebiasis?
Anyone
can get amebiasis, but it occurs more often in travelers or immigrants
arriving from tropical or subtropical areas. It is common in people who
live in developing countries that have poor sanitary conditions. It is
also found in people who live in institutions that have poor sanitary
conditions. Men who have sex with men can become infected and gets sick
from the infection, but they often do not have symptoms.
How
is amebiasis spread?
Amebiasis
is contracted by swallowing the cyst stage of the parasite in contaminated
food or water. It can also be spread by direct or indirect contact with
fecal material from an infected person.
What
are the symptoms of amebiasis?
People
exposed to this parasite may experience mild or severe symptoms or no
symptoms at all. On average, about one in 10 people who are infected with E.
histolytica becomes sick from the infection. The symptoms are quite
mild and can include loose stools, weight loss, abdominal tenderness and
cramping, and fever. In rare cases E.
histolytica invades the liver and forms a liver abscess. Even less commonly, it spreads to other parts of the body such as
the lungs or brain.
How
soon after exposure do symptoms appear?
The
symptoms may appear from a few days to a few months after exposure, but
usually symptoms appear within 2 to 4 weeks.
For
how long can an infected person carry this parasite?
Some
people with amebiasis may be carriers of the parasite for weeks to years,
often without symptoms.
Where
are the parasites that cause amebiasis found?
Infected
people are the only source of the parasite. Fecal material from infected
people may contaminate water or food and may serve as a vehicle to infect
others. Animals are not infected with or carry the parasite. In some parts
of the world, flies may serve to transfer cysts from human feces to fruits
and vegetables.
How
is amebiasis diagnosed?
Examination
of stools under a microscope is the most common way for a doctor to
diagnose amebiasis. Sometimes, several stool
samples collected on different days must be obtained because the number of
parasites (amoeba) shed in feces may vary from day to day.
Diagnosis
of amebiasis can be very difficult. One problem is that other parasites an
cell can look very similar to E.
histolytica when seen under a microscope. Also, E.
histolytica and another ameba, Entamoeba
dispar, which is about 10 times common, look the same when seen under
a microscope. Unlike infection with E.
histolytica, infection with E.
dispar never makes people sick and therefore doe not need to be
treated.
What
is the treatment for amebiasis?
Several
antibiotics are available to treat amebiasis. A doctor must prescribe
treatment.
Should
a person with amebiasis be excluded from work or school?
Generally,
it is not necessary to exclude an infected person from work or school.
Casual contact at work or school is unlikely to transmit the disease. Food
workers, children enrolled in daycare settings or individuals in
institutions for the developmentally disabled may need special
precautions. Consult your local health department for advice in such
instances.
What
precautions should the infected person follow?
The
most important precaution is careful hand washing before eating or
preparing food, after changing diapers and after each toilet visit. Proper
disposal of sewage is also important. Homosexual males should refrain from
intimate contact until effectively treated.
When
traveling to a country that has poor sanitary conditions, what should I
eat or drink so that I will NOT develop amebiasis or other diseases?
-
Drink
only bottled or boiled (for 1 minute) water or carbonated drinks in cans
or bottles and make sure the tops of the bottles or cans are clean.
-
Do
not drink fountain drinks or
drinks with ice cubes.
-
Do
not eat fresh fruit or
vegetables that you did not peel yourself.
-
Do
not eat or drink milk, cheese,
or dairy products that have not been pasteurized.
-
Do
not eat or drink anything sold
by street vendors.
PPH
42024 (05/04)
For more information, contact your
Local
Public Health Department
Back to Communicable Disease
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Last Revised: March 20, 2008
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