Echinococcus granulosus

• Echinococcus granulosus

  Dog Tapeworm or Hydatid Tapeworm
• Echinococcus granulosus

  • Infection is primarily a zoonotic type of infection
  • Dogs are the most important definitive hosts
  • Sheep are usually the intermediate hosts
  • Humans are considered as accidental and dead-end hosts
  • Eggs are identical to those of Taenia spp. and are thus not diagnostic
  • Diagnostic stage is the larval form, which is encased in a cyst wall and is called the hydatid cyst
• Infection with Echinococcus granulosus

  1. Ingestion of eggs (infective stage) from food and water contaminated by dog feces or through contact with contaminated dog feces

  2. Eggs transform into larvae in the intestines

  3. Larvae penetrate the intestines and migrate through the bloodstream to different tissues in the body, particularly the liver and the lungs

  4. Hydatid cyst (pathogenic stage) develops in the infected tissues

  5. Dogs acquire the parasite by eating the visceral organs of the intermediate host
• The eggs of Echinococcus granulosus are identical to those of Taenia spp. and are thus not diagnostic
• The diagnostic stage of Echinococcus granulosus is its larval form, which is encased in a cyst wall and is called the hydatid cyst
• Infection with Echinococcus granulosus is acquired after ingestion of eggs (infective stage) from food and water contaminated by dog feces or through contact with contaminated dog feces
• Dogs acquire the Echinococcus granulosus parasite by eating the visceral organs of the intermediate host
• E. granulosus infection is common in Africa, Europe, Asia, the Middle East, Central and South America, and in rare cases, North America (Centers for Disease Control and Prevention)
• Hydatid cysts


  • They develop from embryos into large, fluid-filled cysts
  • They act as space-occupying lesions
  • The cyst fluid contains antigens that can sensitize the host
• Rupture of the cyst

  May lead to the release of antigens, causing anaphylaxis and widespread dissemination of the parasite
• Disease

  • Echinococcosis
  • Hydatid Cyst Disease
  • Hydatid Disease
  • Hydatidosis
• Early stage of disease

  • Most patients are asymptomatic
• As cysts enlarge

  • Necrosis of infected tissues occurs
  • Involvement of liver may result in obstructive jaundice
  • Patients with lung involvement may manifest with cough, chest pain, and shortness of breath
  • Other organs that may be infected include the spleen, kidneys, heart, bone, and central nervous system, including the brain and eyes
• Cyst rupture

  • May lead to anaphylactic shock leading to death of the patient
• Laboratory Diagnosis

  1. Examination of biopsy specimen

  2. Serologic tests (e.g., ELISA or indirect hemagglutination test)

  3. Radiography to demonstrate the hydatid cysts (e.g., CT scan or ultrasound)
• Care should be exercised when doing biopsy to prevent rupture of the cyst
• Treatment

  1. Removal of the cyst

  2. Medical management alone may prove effective if the cyst is located in inaccessible areas

  3. Drugs that have been proven effective include mebendazole, albendazole, and praziquantel
• Prevention and Control measures

  • Improvement of personal hygiene practices
  • Prevention of contamination of food and water with dog feces
  • Avoidance of feeding pet dogs with contaminated viscera
  • Prompt treatment of infected canines and humans
  • Chemoprophylaxis for dogs in endemic areas
  • Health education