Causes

Human echinococcosis is a zoonotic infection. 3 out of the 4 known species of Echinococcus (a genus of tapeworm) are of medical importance.

Human echinococcosis is a zoonotic infection, i.e. animal diseases that can be transmitted to humans. Animals like cats and dogs get infected when they eat rodents and mice infected with Echinococcus larvae. These larvae matures in the intestines of these animals, lays eggs which pass via stools.

Humans get infected by:

Consuming foods items contaminated with the infected stool.
Handling household cats and dogs that may be infected (fur may be contaminated with stools)

3 out of the 4 known species of Echinococcus (a genus of tapeworm) are of medical importance.

Echinococcus granulosus causes cystic echinococcosis (CE): most common

Echinococcus multilocularis causes alveolar echinococcosis (AE): most virulent (Infectious)

Echinococcus vogeli: very rare

CE is a disease of younger adults, while AE mostly affects older adults. The growth of cysts is slow and takes a long time making diagnosis during childhood rare (unless the brain gets affected).