Echinococcus multilocularis

Background

Microbiology

• Cestode in the Echinococcus family
• Disease is caused by the larval form

Life Cycle

• Definitive hosts are canid carnivorous animals
• Eggs contaminate the environment, including produce
  • They are infective after a few days, and are viable for up to 16 months at 4ºC
• Intermediate hosts (metacestode) are rodents, possibly pigs, and and incidentally humans
• Intermediate host is eaten by the definitive host, completing the life cycle

Clinical Manifestations

• Causes alveolar echinococcosis
• Incubation period 5 to 15 years
• Vague abdominal pain may precede diagnosis by years
• Presents as a metastatic malignancy of unknown primary, mot commonly with malaise, weight loss, and right upper quadrant discomfort
  • May also mimic hepatocellular carcinoma, cirrhosis, and tuberculosis
  • Causes continuously-growing tumour-like polycystic mass, made up of multiple vesicles that are lined by laminated germinal layer
• Can cause cholestatic jaundrice, cholangitis, portal hypertension, and Budd-Chiari syndrome

Diagnosis

• Combination of radiologic and serologic investigations
• May be confirmed by biopsy

Management

• Main treatment is surgical resection followed by at least 2 years of antihelminthic therapy (e.g. albendazole)
• Poor prognosis, with 90% 10-year mortality if untreated