Dog Tapeworm Infection
(Echinococcosis; Hydatid Disease)
Dog tapeworm infection is infection that is caused by the tapeworms Echinococcus granulosus and Echinococcus multilocularis. It can cause cysts to form in various organs (called echinococcosis).
Adult tapeworms of Echinococcus granulosus and Echinococcus multilocularis live in the intestine of dogs or other canines. These tapeworms sometimes infect people, causing cysts in the liver or other organs.
Dogs, particularly herd dogs, become infected when they consume cysts of the tapeworms in tissues of infected animals (such as sheep, goats, cattle, or pigs). The cysts (called hydatid cysts) develop into adult tapeworms in the dog's intestine. Infected dogs pass tapeworm eggs in their stool. Sheep, cattle, goats, or pigs consume tapeworm eggs in soil contaminated with dog stool. Inside these animals, the eggs hatch and develop into cysts in the animal's internal organs.
People (often shepherds) are usually infected when they accidentally consume soil, water, or food that has been contaminated by Echinococcus eggs passed in dog stool.
Tapeworm eggs remain alive in soil for up to a year. Eggs may also be present on the fur of infected animals. After people touch an infected animal, they may pick up eggs, transfer the eggs from their hands to their mouth or to food, and thus become infected.
The eggs hatch in the intestine and release spheres that contain tapeworm larvae. The spheres penetrate the wall of the intestine and travel through the bloodstream to various organs, such as the liver and lungs. In these organs, the spheres develop into cysts, which enlarge gradually and which, in people, can cause symptoms. The resulting infection is called echinococcosis.
Echinococcosis symptoms include the following :
Abdominal pain and jaundice if cysts form in the liver
Chest pain and coughing up blood or the contents of cysts if cysts form in the lungs
Hives or a severe life-threatening allergic reaction (anaphylaxis)
In people with echinococcosis, cysts in the liver or other tissues can be seen using ultrasonography, computed tomography (CT) or magnetic resonance imaging (MRI).
Blood tests for antibodies to the dog tapeworm may also be helpful. (Antibodies are proteins produced by the immune system to help defend the body against attack, including that by parasites.
Doctors can often surgically remove the cyst or drain the cyst with a needle. To drain the cyst, they use ultrasonography to guide placement of the needle. They then inject a salt solution into the cyst to kill the parasites, then drain the solution out (a procedure called percutaneous aspiration-injection-reaspiration).
After surgery or draining, albendazole is usually given. It reduces the likelihood that a cyst will come back or spread. It can kill some cysts but then must be take a long time. Albendazole is also used to suppress the growth of cysts that cannot be removed surgically or drained.