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Echinococcosis in Cats

By Catherine Barnette, DVM

Infectious Diseases, Zoonosis & Human Health, Pet Services

What is echinococcosis?

Echinococcosis refers to being infected with a tapeworm of the genus Echinococcus. In the Northern Hemisphere, this tapeworm is Echinococcus multilocularis. This parasite is found primarily in Canada and the Midwestern United States, though its range appears to be extending south and east over time.

E. multilocularis is primarily a parasite of coyotes and foxes, but it also spends a portion of its lifecycle within rodents (rodents are intermediate hosts). Cats can become infected with echinococcosis by eating an infected rodent (e.g., mice and squirrels), although infection is more common in dogs.

Is E. multilocularis contagious to people?

Yes. E. multilocularis is a zoonotic parasite, meaning that it can be passed between humans and animals. Humans become infected through the accidental ingestion of E. multilocularis eggs, which can be shed in the feces of infected pets.

In humans, E. multilocularis causes large cysts to form within the lungs and liver. These cysts can grow so large that they interfere with organ function, making echinococcosis one of the most serious known zoonotic diseases. Even with surgery and medical treatment, infection is often fatal.

How is echinococcosis diagnosed?

Infected cats are usually asymptomatic (show no symptoms). This disease typically has little impact on cats, because it remains confined to the gastrointestinal tract in most cases. It is primarily a concern because of its potential effects on human health.

"Infected cats are usually asymptomatic."

In rare cases, visible tapeworm segments may be seen around the rectum of infected pets. This is uncommon with E. multilocularis (visible tapeworm segments are far more likely to belong to other, less-problematic tapeworm species), but can occur. Additionally, E. multilocularis eggs may be seen on microscopic examination of the feces, but these eggs cannot be distinguished from those of other tapeworm species.

Definitively diagnosing E. multilocularis requires specialized testing. Your veterinarian may send your pet’s fecal sample to an off-site laboratory, where specific tests can be performed to determine which tapeworm species is present in your pet. These tests are not routinely recommended however, as the treatment for all tapeworm species is identical; knowing which tapeworm species is present does not influence treatment.

How is echinococcosis treated?

E. multilocularis is treated with praziquantel, the same medication that is used to treat other tapeworm species. This medication can be given by mouth or as an injection.

In rare cases, cats may develop internal cysts related to E. multilocularis (similar to human infection). If this occurs, the cat is typically treated with a combination of surgery and multiple deworming medications.

What is the prognosis for echinococcosis?

The prognosis is good in most cases, because most cats experience only gastrointestinal involvement. These pets rarely experience clinical signs and typically clear the parasite fully with treatment.

Cats with internal cysts caused by E. multilocularis have a variable prognosis. In some cases, these cysts can be surgically removed. In the case of multiple cysts that cannot be surgically removed however, the prognosis is poor.

How can I prevent echinococcosis in my cat?

The best way to prevent echinococcosis is to keep your cat indoors or prevent her from roaming and ingesting live or dead rodents. It is also important to limit your cat’s exposure to the feces of sheep, cattle, and pigs, as these animals can also shed Echinococcus eggs in their feces.

Additionally, consider deworming your cat with praziquantel once monthly. This deworming will prevent echinococcosis, as well as other tapeworm species.

How can I prevent echinococcosis in myself?

Always wash your hands thoroughly after handling your cat’s stool and cleaning her litter box. This will protect you from echinococcosis, as well as a number of other intestinal parasites.

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