Efficacy of killing Echinococcus granulosus protoscoleces (PSCs) by boiling sheep lungs containing hydatid cysts. Panel I: (a) normal PSCs were collected from cysts before boiling; (b–e) PSCs were collected from sheep livers boiled for 5, 10, 20 and 30 min, respectively. Panel II: (A) a non-boiled sheep lung containing E. granulosus cysts; (B–E) lungs boiled for 5, 10, 20 and 30 min, respectively. PSCs stained in blue are dead PSCs.