Echinococcus

A tiny parasitic tapeworm.

The larval stage of this tapeworm can cause human disease.

There are three forms of Echinococcus that affect humans -- E.

(Echinococcus) granulosus, E.

Multilocularis, and E.

Vogeli -- and each has a different geographic distribution and tends to cause a different pattern of disease.

E.

Granulosus is common in areas where livestock is raised in association with dogs -- in Australia and New Zealand, Argentina and Chile, Africa, E.

Europe, the Middle East, and the Mediterranean region, especially Lebanon and Greece -- and causes unilocular cysts.

E.

Multilocularis is found in Alpine, sub-Arctic, or Arctic regions -- including Canada, the United States, and central and northern Europe and Asia -- and causes multilocular lung disease known as alveolar hydatid disease (AHD).