What is Echinococcosis or hydatid disease? | Outbreak News Today Outbreak News Today
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What is Echinococcus?

Echinococcus granulosus is a relatively small tapeworm (3-6 mm in length) that is found in dogs and other canids, wolves for example. Humans are accidentally infected through association with dogs.

Where is this parasite found?

Hydatid disease

Hydatid disease Image/CDC

It can be found anywhere there is a close association with infected dogs. It is most common in animal raising areas where dogs get infected when they eat uncooked, contaminated organs of sheep, cattle or pigs. In the United States, human echinococcosis has been found in sheep ranchers in California, Arizona, New Mexico and Utah. Sheep and similar intermediate hosts are infected when grazing in pastures contaminated with dog or wolf feces that contain infective eggs. The infective eggs in nature can survive for up to a year in the environment.

What is the disease in humans?

Many infections in people are asymptomatic. E. granulosus produce a hydatid cyst which can grow up to 15 cm or more. Sometimes the cyst may die or become calcified producing little or no disease. However, the cysts can be found in almost any organ as a space-occupying lesion (liver and lungs being most common). Some of the complications of having the cyst are if they rupture from compression or become infected. A ruptured or leaking cyst can cause severe anaphylactic reactions and release tiny “tapeworm heads” known as protoscolices which can lead to secondary and metastatic infections throughout the body.

How in Echinococcus diagnosed?

It is based on the signs and symptoms of a slow-growing tumor in conjunction with residence in an endemic area. Ultrasounds, CAT scans and serologic tests can be useful in the diagnosis.

How is echinococcosis or hydatid disease treated?

Treatment depends on the size, location and health of the patient. Surgery is the method of choice to remove cysts. There are risks to the surgery though, with potential leakage of the cysts being most important. Anti-parasitic medications can be used to prevent secondary infections. There is now a method available for treating cysts in the abdomen where the fluid from the cyst is aspirated, then treating with a drug to kill the “tapeworm heads”, and then aspirating that fluid

How can you prevent getting infected?

Basic hygiene techniques of handwashing and avoiding ingestion of raw vegetables and water that has been contaminated with feces of infected dogs. Hunters should use gloves when handling canids (wolves or coyotes) or their feces. Also you can prevent the cycle by not letting dogs have access to contaminated offal. Periodic treatment of high-risk dogs is highly recommended.



  1. Mark Thorson says:

    It’s probably not just dogs and wolves. In California, we have very few wolves. But coyotes are common. They’ve been sighted in San Francisco, and I’ve seen them many times here in Saratoga, just west of San Jose. I’ve also seen coyote feces deposited in my yard several times. Now I know those things are potentially harboring a dangerous parasite. I don’t have any sheep, but wild deer are in my yard almost every day. I suppose I should bury the coyote feces every time I see them. Coyote feces look just like dog feces except they have all these orange chunks in them, as though they had been eating carrots. I’m curious what causes that.

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