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What
is echinococcosis?
Echinococcosis
or hydatid disease results from being infected with the larvae
(a developing phase) of the tapeworms Echinococcus granulosus,
E. multilocularis, or E. vogeli. E. granulosus
is found most commonly in dogs that consume the viscera of infected
sheep, but can also be found in coyotes, wolves, dingos, and
jackals. E. multilocularis is found in foxes, coyotes,
dogs and cats. E. vogeli has been identified only in
Central and South America, and will not be discussed further.
Infection
with E. granulosus results in the formation of cysts
in the liver, lungs, kidney and spleen. This condition is also
known as cystic hydatid disease and can usually be successfully
treated with surgery. Infection with E. multilocularis
results in the formation of parasitic tumors in the liver, lungs,
brain, and other organs. This condition is more likely to be
fatal than the disease caused by E. granulosus. It
is also called alveolar hydatid disease.
Who
gets echinococcosis?
Anyone
can get echinococcosis by swallowing the eggs of the E.
granulosus or E. multilocularis tapeworm. Echinococcal
infections among humans occur worldwide, although they are rare.
The primary areas where E. granulosus has been found
in North America include sheep-raising regions of Utah, California,
Arizona and New Mexico. The primary areas where E. multilocularis
has been found in North America include the north central region
from eastern Montana to central Ohio, as well as Alaska and
Canada.
How
is echinococcosis spread?
Dogs,
coyotes, wolves, dingos and jackals get infected with E.
granulosus when they eat the viscera of infected sheep
or other animals. Once they become infected, they will pass
the eggs in their stool. These very tiny eggs are directly infectious
to other animals and humans.
Foxes,
coyotes, dogs and cats get infected when they eat E. multilocularis
larvae in infected rodents. Once they become infected, they
will pass the eggs in their stool. These very tiny eggs are
directly infectious to other animals and humans.
Humans
are usually exposed to these eggs in one of two ways:
- By
directly ingesting food items or drinking water that is
contaminated with stool from an infected animal.
- By
petting or having other contact with cats and dogs that
are infected. These pets may shed the eggs in their stool,
and their fur may be contaminated. They may also contaminate
other objects, such as harnesses or leashes, which can also
spread infection.
How
soon after exposure do symptoms appear?
Because
the cysts are usually slow-growing, infection may not produce
symptoms for years. Symptoms usually reflect the size and location
of the cysts.
How
is echinococcosis diagnosed?
Echinococcosis
is diagnosed by a blood test that can detect the presence of
antibodies to the parasite. The disease may also be diagnosed
by directly identifying the parasite in fluid or tissue samples.
What
is the treatment for echinococcosis?
Surgery
is the most common form of treatment for echinococcosis. Removal
of the cyst may not be 100% effective, and medication may be
necessary to keep the cyst from growing back.
How
can echinococcosis be prevented?
Two
steps can help prevent both kinds of echinococcosis and other
diseases as well:
- After
handling pets, always wash your hands with soap and warm
water.
- Do
not eat wild fruits or vegetables picked directly from the
ground without careful washing or cooking.
Other
steps can be taken to prevent E. granulosus:
- Do
not feed sheep viscera to dogs.
- Do
not allow dogs to have access to sheep carcasses.
If
in an area where E. multilocularis is found, take the
following precautions:
- Don't
touch a wild canine, dead or alive, without wearing gloves.
- Don't
keep wild canines as pets or encourage them to come close
to your home.
- Don't
allow your cats and dogs to wander or to capture and eat
rodents.
- If
you think that your pet may have eaten rodents, consult
your veterinarian about the possible need for preventive
treatments.
Where
can I get more information?
- Your
personal doctor or veterinarian.
- Your
local health department listed in your telephone directory.
- The
Utah Department of Health, Bureau of Epidemiology (801)
538-6191.
UTAH
DEPARTMENT OF HEALTH
BUREAU OF EPIDEMIOLOGY
August 2001
This
fact sheet was based on the Center for Disease Control and Prevention's
Alveolar Hydatid Disease (Echinococcosis) sheet (last updated
2/2/98).
