The histogenesis of the hydatid cyst (Echinococcus spp.) Part 1. Liver cysts in large mammals

Abstract

The reaction of the intermediate host to the presence of the hydatid cyst in all animals follows a generally similar pattern, modified somewhat by the species of host and the organ invaded. This reaction is a complex of factors which vary in kind as well as degree as the parasite slowly grows. These include the effects of growth and development, excretions and secretions, and the enlargement of a laminated protective membrane; the host reacts by a stage of inflammation, repair, and the deposition of a fibrous tissue adventitia. The host reaction is not organically attached to the parasite which if not killed continues to grow to a considerable size (optimum about 10 cm) causing increased pressure atrophy of the host tissue. In the early stages of growth there is a great local production of tissue eosinophiles by the host, which later gradually subsides.This paper describes the histology of the effect of Echinococcus granulosus on the livers of pigs, sheep, bovines, deer, and equines and the reaction to its presence.