Experimental infection of Libyan sheep with Echinococcus granulosus.

The growth rate of unilocular hydatid cysts over a two-year period was studied in Libyan sheep dosed orally with gravid segments of Echinococcus granulosus taken from stray town dogs. Seven of the eight sheep dosed with 20-100 gravid segments (say 4000-20,000 eggs) had developed only infertile hydatid cysts after 107-611 days. Sheep dosed with 1000 gravid segments (say 200,000 eggs) had developed only sterile cysts when examined 358 days after dosing. Fertile cysts were recovered from the lungs after 428 days, and after 584 days from the liver. Only sterile cysts were seen in the heart, spleen and kidneys.