Makindo Medical Notes

Hydatid Disease (Echinococcus)

The PAIR approach (Puncture, Aspirate cyst, Injection of hypertonic saline solution or ethanol, and Re-aspiration) is now the preferred minimally invasive management technique.

About

• Hydatid Disease: Caused by infection with the tapeworm Echinococcus, leading to the formation of cysts.
• E. granulosus: Typically causes cystic (unilocular) disease, primarily affecting the liver and lungs.
• E. multilocularis: Often leads to alveolar (multilocular) disease, commonly affecting the liver and lungs, with a more aggressive, invasive behavior.

Aetiology

• Definitive Hosts: Dogs, who release ova in feces that infect intermediate hosts like cattle and sheep.
• Geographic Distribution: Hydatid disease is endemic in regions like Central Europe, the Mediterranean, the Middle East, South America, Australia, New Zealand, and parts of South Africa.

Clinical Presentation

• Asymptomatic Early Stages: Cysts often develop slowly and remain subclinical for years.
• Liver Cysts (60% cases): Commonly in the right lobe, may present with abdominal pain, hepatomegaly, or jaundice if cysts compress the biliary tree.
• Brain Cysts: May present with neurological symptoms such as epilepsy or raised intracranial pressure.
• Pulmonary Cysts: Hemoptysis, cough, dyspnea, or localized chest pain.
• Bone Cysts: Can cause localized pain and pathological fractures due to cystic expansion within the bone.
• Kidney Cysts: Flank pain and hematuria.
• Ruptured Cyst: Leads to acute hypersensitivity reactions, including fever and potentially life-threatening anaphylaxis.

Investigations

• Blood Eosinophilia: Often seen in systemic infections with parasitic infestations.
• Imaging (CT, MRI, or Ultrasound): Essential for identifying cyst location, size, and internal characteristics.
• Serology: Useful for detecting antibodies against Echinococcus, though sensitivity varies based on cyst location.
• Percutaneous Cyst Aspiration: Under ultrasound guidance, aspiration may reveal clear, watery fluid with scolices. Elevated pressure may indicate an active cyst. Risk of anaphylaxis and spread requires experienced handling.

Management

• PAIR Approach:
  • Puncture, Aspirate cyst, Inject with hypertonic saline or ethanol, and Re-aspirate to reduce infection risk and minimize cyst content spillage.
  • Particularly effective for cysts in accessible areas like the liver and lungs.
• Surgical Management:
  • Laparotomy with packing of surrounding area with hypertonic saline-soaked swabs to prevent spillage.
  • Injections of 0.5% silver nitrate or 100% ethanol are used to inactivate cyst contents before aspiration or removal.
  • Complete cyst removal, known as pericystectomy, may be required in complex cases.
• Pharmacological Treatment:
  • Albendazole and Praziquantel: Common preoperative treatment to reduce cyst viability. Albendazole is usually continued postoperatively to prevent recurrence.
  • Metronidazole: May be used in combination for certain cases.

Notes:

• Risk of Anaphylaxis: Rupture of hydatid cysts, either spontaneously or during procedures, can lead to severe allergic reactions. Emergency protocols should be in place.
• Prevention: Regular deworming of dogs, proper meat handling, and avoiding close contact with infected animals in endemic regions.