Echinococcus granulosus – Unilocular Hydatid Cyst

  • Develops in lung, liver, etc., of intermediate host (sheep, cattle, human)
  • Infective stage to the definitive host, i.e., dog
  • Diagnosis of infection in human: Finding hydatid cyst via imaging and histological techniques or via immunological techniques that detect antibodies
Morphological Features
  • Spherical fluid filled (hydatid fluid) structure
  • Size: around 10 mm in diameter
  • Can observe endocyst and ectocyst
  • Outermost ectocyst: Fibrous layer of host tissue; develops as a result of a host reaction
  • Inner endocyst: Parasite origin; consists of a striated laminated layer and an inner germinal layer
  • Site of asexual reproduction: Germinal layer – produce brood capsules that bud off protoscolices
  • Protoscolices: round to oval in shape; contain hooks – each protoscolex is a potential adult tapeworm
  • Mature hydatid cysts may also form daughter cysts and granddaughter cysts
  • Hydatid sand: Granular material in hydatid fluid that contains free protoscolices

Magnification x4

Magnification x40