Echinococcus multilocularis is a cyclophyllid cestode that, like Echinococcus granulosus, produces hydatid disease in many mammals, including rodents and humans. Unlike E. granulosus, E multilocularis produces many small cysts ("multilocular infection ") that spread throughout the infected animal. When these cysts are ingested by a canid, usually by eating an infected rodent, it produces heavy infection with tapeworm adults.

These adults produce eggs and proglottids that are passed with feces. Small rodents serve as the most common intermediate hosts, but humans that ingest eggs or proglottids may also become infected.

A study by Purdue veterinary parasitologists indicated that the disease is spreading throughout the American Midwest, where it was previously rare or nonexistent. Additionally, the disease has extended its range in Europe in the last few decades[1].