Cysts are abnormal closed cavities within the body, usually containing liquid.
Hydatid cysts are formed during the larval stage of Echinococcus tapeworms.
All disease-causing species of Echinococcus are transmitted via the ingestion of eggs by means of eating infected, cyst-containing organs.
Humans are accidental hosts that become infected by handling soil, dirt or animal hair that contains eggs.
Echinococcus infestations can usually be treated with medicine and cysts can be removed during surgery (depending on the location of the cysts, complications may arise).