Who is at risk for cystic echinococcosis (CE)?

People who accidentally swallow the eggs of the Echinococcus granulosus tapeworm are at risk for infection. Humans can be exposed to these eggs in two main ways that involve "hand-to-mouth" transfer or contamination.

• By ingesting food, water or soil contaminated with stool from infected dogs. This might include grass, herbs, greens, or berries gathered from fields.
• By petting or handling household dogs infected with the Echinococcus granulosus tapeworm. These dogs may shed the tapeworm eggs in their stool, and their fur may be contaminated.

Where is cystic echinococcosis (CE) found?

CE is found in Europe, Asia, Central and South America, the Middle East, and Africa. Highest prevalence is found in populations that raise sheep. In North America, Echinococcus granulosus is found primarily in Canada and Alaska, but human cases have also been reported in Arizona and New Mexico. In the United States, most infections are diagnosed in immigrants from counties where CE is endemic.

How is cystic echinococcosis (CE) spread?

The most common way of becoming infected with CE involves contact with infected dogs. Dogs that eat home-slaughtered sheep and other livestock become infected and Echinococcus granulosus eggs can be found in their stool and in dog hairs. Direct contact with infected dogs, particularly intimate contact between children and their pet dogs, leads to human infection. Indirect contact through soil, water and contaminated vegetables may also lead to infections. Echinococcus granulosus eggs can survive snow and freezing conditions. Risk factors for human infection include uncontrolled dogs living closely with people, uncontrolled slaughter of livestock, and unsanitary living conditions.

What are the symptoms of cystic echinococcosis (CE)?

CE is caused by cyst-like tapeworm larvae growing in the body. CE usually involves the liver or the lungs, but can spread to other organs of the body. Because the cysts are slow-growing, infection with CE may not produce any symptoms for many years. Pain or discomfort in the upper abdominal region or chest, nausea, vomiting, or coughing may occur as a result of the growing cysts. Rupture of cyst fluid can lead to allergic reactions or even death.

How do I know if I have cystic echinococcosis (CE)?

See your health care provider if you think you may have been exposed to the parasite by one of the ways listed above. Radiologic exams (X-rays) are helpful to see the cysts in most organs. Diagnosis of CE can be made by a blood test that looks for the presence of the parasite or antibodies to Echinococcus granulosus.

How is cystic echinococcosis (CE) treated?

Until recently, surgery was the only option for treatment of CE. However, now medication and a modified surgical procedure (aspiration) are increasingly used and can replace the need for surgical removal of the hydatid cysts. Even so, surgery may be necessary in certain circumstances. After surgery, medication may be needed to keep the cyst from growing back.

Can cystic echinococcosis (CE) be prevented?

If you live in an area where Echinococcus granulosus is found in sheep or cattle, take the following precautions to avoid infection:

• Wash your hands with soap and warm water after handling dogs, and before handling food.
• Teach children the importance of washing hands to prevent infection.
• Avoid ingestion of food, water or soil contaminated with stool from dogs. This might include grass, herbs, greens, or berries gathered from fields.
• Don't allow your dogs to wander freely or to capture and eat raw meat from sheep, cattle, pigs, and goats.
• Don’t home slaughter sheep and other livestock
• If you think your pet may have eaten infected meat, consult your veterinarian about the possible need for preventive treatments.

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This information is not meant to be used for self-diagnosis or as a substitute for consultation with a health care provider. If you have any questions about the disease described above or think that you may have a parasitic infection, consult a health care provider.