Humans become infected when they swallow the tapeworm eggs in contaminated food. The eggs then form cysts inside the body. A cyst is a closed pocket or pouch. The cysts keep growing, which leads to symptoms.
E granulosus is an infection caused by tapeworms found in dogs, and livestock such as sheep, pigs, goats, and cattle. These tapeworms are around 2 to 7 mm long. The infection is called cystic echinococcosis (CE). It leads to growth of cysts mainly in the lungs and liver. Cysts can also be found in the heart, bones, and brain.
E multilocularis is the infection caused by tapeworms found in dogs, cats, rodents, and foxes. These tapeworms are around 1 to 4 mm long. The infection is called alveolar echinococcosis (AE). It is a life-threatening condition because tumor-like growths form in the liver. Other organs, such as the lungs and brain can be affected.
Children or young adults are more prone to get the infection.
Echinococcosis is common in:
- Central Asia
- Southern South America
- The Mediterranean
- The Middle East
In rare cases, the infection is seen in the United States. It has been reported in California, Arizona, New Mexico, and Utah.
Risk factors include being exposed to:
- Feces of dogs, foxes, wolves, or coyotes
Echinococcosis is an infection caused by either the Echinococcus granulosus or Echinococcus multilocularis tapeworm. The infection is also called hydatid disease.
Exams and Tests
The health care provider will perform a physical exam and ask about the symptoms.
If the provider suspects CE or AE, tests that may be done to find the cysts include:
- X-ray, CT scan, or ultrasound to view the cysts
- Blood tests, such as enzyme-linked immunoassay (ELISA), liver function tests
Most often, echinococcosis cysts are found when an imaging test is done for another reason.
If the cysts respond to oral medicines, the likely outcome is good.
Measures to prevent CE and AE include:
- Staying away from wild animals including foxes, wolves, and coyotes
- Avoiding contact with stray dogs
- Washing hands well after touching pet dogs or cats, and before handling food
Cysts may produce no symptoms for 10 years or more.
As the disease advances and the cysts get larger, symptoms may include:
Many people can be treated with anti-worm medicines.
A procedure that involves inserting a needle through the skin into the cyst may be tried. The contents of the cyst is removed (aspirated) through the needle. Then medicine is sent through the needle to kill the tapeworm.
The cysts may be removed with surgery, if possible. But this can be a complicated surgery.
When to Contact a Medical Professional
Call your provider if you develop symptoms of this disorder.
Fischer PR, Cabada MM, White AC. Echinococcosis (Echinococcus granulosus and Echinococcus multilocularis). In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 304.
King CH, Fairley JK. Tapeworms (Cestodes). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Updated Edition. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 291.
Parasites-echinococcosis. Centers of Disease Control and Prevention Web site. Updated December 12, 2012.
White AC, Fischer PR, Legua P. Cestodes. In: Cherry JD, Harrison GJ, Kaplan SL, Steinbach WJ, Hotez PJ, eds. Feigin and Cherry's Textbook of Pediatric Infectious Diseases. 7th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 226.