Serial passages of larval Echinococcus granulosus from equine origin in mice. I. Infection with protoscolices.

Starting with protoscolices from Echinococcus granulosus cysts of equine origin it was possible to isolate and maintain several "strains" of the parasite in mice through successive transfers of protoscolices. The most advanced strain is now in its 7th generation. Several criteria to evaluate the results are presented and discussed. It is concluded that serial echinococcosis of E. granulosus through passages with protoscolices is a practical method to maintain different strains for fundamental and applied comparative studies.