Echinococcosis

Background

  • 2 most important forms are cystic and alveolar caused by E. granulosus and E. multilocularis
  • Humans are accidental immediate hosts by ingesting parasitic eggs from contaminated food, soil, water, or direct contact with definitive hosts
  • Usual intermediate hosts-sheep, goat, swine, cattle, rodents and camel
  • Definitive hosts-dogs, cats, fox, and wolves
  • Ingested eggs then hatch, penetrate intestinal mucosa, and spread hematogenously to final destination to form cysts

Clinical Features

  • Asymptomatic for many years
  • Abdominal cysts- pain, distension, nausea and vomiting
  • Alveolar abscess-chest pain, shortness of breath, chronic cough
  • Musculoskeletal pain, blindness, headache, and stroke like symptoms if involving muscles, bones, eyes or brain

Differential Diagnosis

Hepatic abscess

Evaluation

Work-up

  • Abdominal Ultrasound (most widely used)
  • CT
  • MRI
  • ELISA-sensitivity inversely related to antigen sequestration in cysts
  • Percutaneous aspiration

Management

  • Tissue stage/hydatid disease: albendazole 400mg BID x 28 days, repeat as needed every 2 weeks x 3 cycles
  • Surgical removal
    • Do not aspirate cysts (risk of seeding disease or anaphylactoid reaction from spillage of hydatid sand which contains antigenic proteins)
    • PAIR (Percutaneous aspiration, injection, reaspiration)
      • Inject with 95% ethanol or hypertonic saline, leave in for 15 minutes, then reaspirate

Disposition

  • Discharge (if no significant clinical complications)

See Also

References