1. Pulmonary Echinococcus
Megan Brundrett
December 15, 2009

2. Pathology 1

3. Pathology 2

4. Echinococcus Cestodes – divide their life cycle in 2 or more hosts
Intermediate host – immature parasite as a tissue cyst
Definitive host – mature parasite as a tapeworm
Echinococcus granulosus
Echinococcus multilocularis

5. E. granulosus Hydatid disease
Definitive hosts are dogs or other canines
Intermediate hosts – sheep, goats, camels, horses, humans
Australia, New Zealand, Argentina, Chile, Ireland, Scotland, middle Europe, Kenya

6. E. multilocularis Alveolar disease
Definitive host – foxes, and other canines
Intermediate host – rodents, humans
Arctic areas of United States, Canada, and Russia

7. Life Cycle (1) Adult tapeworms in bowels of definitive host
(2) Eggs passed in feces, ingested by intermediate host
(3) Onchosphere penetrates intestinal wall, carried via blood vessels to lodge in organs
(4) Hydatid cysts develop
(5) Protoscolices (larvae) ingested by definitive host
(6) Attach to small intestine of definitive host and grow to adult worm.

8. Hydatid disease E. granulosus 75% hepatic involvement, 25% pulmonary
Other organs – brain, bone, heart, kidney
Cause symptoms with mass effect, rupture, secondary infection

9. Alveolar disease E. multilocularis
< 5% of symptomatic Echinococcal infections
Lacks a limiting membrane like hydatid disease and causes more infiltration to surrounding tissues.
Clinical presentation – jaundice, RUQ pain, malaise
If untreated >90% die within 10 years
Now prognosis improved b/c of albendazole therapy. Very difficult to surgically resect.

10. Pulmonary Echinococcal Diease
60% right lung
50-60% in lower lobes
Lungs may be a more common site in children
30% have multiple cysts in the lungs
20% of pts with lung involvement have liver involvement

11. Clinical Manifestations
Unruptured cyst: Chest pain, hemoptysis, chronic cough
Ruptured cyst: Cough, fever, expectorating salty material (hydatid membrane and larvae).
Acute hypersensitivity with rupture: Fever, urticaria, sometimes anaphylaxis
Superinfection by bacteria, fungal presenting with fever, sepsis
Pulmonary HTN, Pulmonary embolism

12. Diagnosis
CXR: Round or oval mass with smooth borders. No calcifications. If pericyst (fibrous capsule that host makes) incorporates bronchioles, than air penetrates between the pericyst and exocyst creating a meniscus sign or crescent shape.
CT scan: Thin enhancing ring if cyst is intact. Fluid filled in center. Homogenous.

13. CXR

14. Differential Diagnosis
Primary lung cancer
Metastatic cancer
Tuberculosis
Bronchogenic Cyst
Round pneumonia
Aspergillosis

15. Laboratory Data
Less than 15% have peripheral eosinophilia, only if leakage of antigenic material
Immunodiagnostic testing for serum antibodies: + 50% for pulmonary, > 90% for hepatic
- False positive if have another parasitic infection
- More likely to have false negative if intact cyst
Percutaneous aspiration: Not often use in pulmonary echinococcus, but used with hepatic cysts for diagnosis and treatment. Fluid contains hooklets, protoscolices, etc.

16. Management Surgical resection: Treatment of choice
Minimize spilling of contents to prevent spread, and allergic reaction
Intact cyst
Cystic fluid aspiration, and scolicidal solution (hypertonic saline) for deactivation
Recurrance rate after removal 1-3%

17. Management 2
Chemotherapy: Used with poor surgical candidate, unresectable lesion, multiple cysts, after cyst rupture, or if intraoperative spillage
Prior to surgery reduces tension of cyst
Albendazole 400 mg PO BID
Length of treatment 3-6 months
No established monitoring guidelines for response of therapy
Disappearance of cysts in 30%, decrease in size in 30-50%, no change in 20%
25% relapse rate, more common with multiple cysts, children and elderly adults

18. Prevention Avoiding close contacts with dogs
Careful washing of hands, and produce
Prohibition of home slaughter of sheep and to prevent dogs from eating the infected viscera
Treating infected dogs with Praziquantal
Eliminating stray dogs
Vaccination: Appears to be 95% effective in animal studies, not used on humans currently

19. References
“Clinical manifestations and diagnosis of cystic and alveolar echinococcosis.” UptoDate <
Goldman, Lee et al. Cecil Textbook of Medicine. Philadephia: Saunders, 2004.
Morar,R and Feldman,C. Eur Respir J 2003; 21:
“Treatment and prevention of echinococcus.” UptoDate <