What animal harbors the adult tapeworm of Echinococcus granulosus?

The adult tapeworm of Echinococcus granulosus primarily resides in the intestines of definitive hosts, which are typically canids, most notably dogs. These animals play a crucial role in the lifecycle of the parasite, as they shed the eggs in their feces, which can then infect intermediate hosts such as sheep, cattle, and humans.

In this lifecycle, dogs ingest the larval cysts from the tissues of infected animals like sheep, cattle, or even humans. Once ingested, the larval forms develop into adult tapeworms in the dog's intestines, completing the cycle. This relationship highlights the significance of the canine host in the transmission and maintenance of Echinococcus granulosus in the environment.

While sheep, cattle, and humans can serve as intermediate hosts for the larval stages that develop into cysts within their bodies, they do not harbor the adult form of the tapeworm, making dogs the correct answer regarding the host of the adult tapeworm.