Hydatid disease - Echinococcosis



Background

echinococcus life cycle - Thank you CDC-DPDx team
Image with kind permission of the CDC-DPDx team.
  • Infection caused by the larval stage of small taeniid-type tapeworms of the Echinococcus species.
  • 3 forms of human hydatid disease
    • E granulosus unilocular cyst
    • E vogeli unilocular cysts
    • E multilocularis multilocular locally invasive
  • The adult form of E granulosus (3-5mm long) inhabits the intestines of definitive hosts (e.g. dogs)
  • Ingested eggs hatch into embryos which penetrate intestine, portal circulation to liver
  • Hydatid cysts in liver (occas. other organs e.g. lungs / brain).
  • Each cyst, grows 2 cm/year, has 2 layers
    • endocyst = fluid
    • pericyst = capsule, new larvae site

Clinical

  • Most uncomplicated cysts asymptomatic
  • Maybe vague RUQ pain ± liver mass
  • Rarely, raised eosinophil count
  • Cyst rupture
    • Intra-biliary = jaundice, colic, ascending cholangitis
    • Intra-peritoneal = severe abdo pain, peritonism
    • Allergic reaction common (± anaphylaxis), eosinophilia
    • Pulmonary cyst = chest pain, cough, haemoptysis

Investigations

  • Plain x-rays for pulmonary masses - heterogeneous appearance
  • Ultrasound for hepatic, fluid filled, cysts
  • CT for pre-op planning
  • Serological immunoelectrophoresis most sensitive for diagnostic and monitoring
  • ELISA less specific and may remain positive for months after curative surgery.

Treatment

  • Surgical cystectomy (aspiration and injection if inoperable) is treatment of choice
  • Albendazole / mebendazole for those where surgery contraindicated.


Content by Dr Íomhar O' Sullivan, 11/06/2009. Last review Dr ÍOS 10/06/21.