In hydatid disease, which classification correctly identifies the causative agent and its host?

The correct classification for hydatid disease involves identifying Echinococcus granulosus as the causative agent and recognizing its relationship with its hosts. Echinococcus granulosus is a parasitic tapeworm that primarily affects canines (such as dogs) as its definitive hosts, where the adult tapeworm lives in the intestines. Humans can serve as accidental intermediate hosts when they ingest the eggs of the parasite, often through contaminated food or water.

In the case of hydatid disease, the larvae can develop into cysts in various organs, primarily the liver and lungs, leading to significant health complications. This is different from the role of definitive hosts, where parasitic maturation occurs.

Thus, the connection of Echinococcus granulosus with accidental intermediate hosts accurately reflects the role of humans in this disease cycle, highlighting the nature of transmission and the implications for health.