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echinococcosis (hydatid disease)
Etiology:
1) Echinococcus granulosus
2) Echinococcus multilocularis
3) Echinococcus vogeli
Epidemiology:
1) distribution is species dependent
2) definitive hosts are dogs that pass eggs in their feces
3) humans are intermediate hosts
4) infection acquired after ingestion of eggs
5) when dog ingests beef, lamb, rodent etc containing cysts, the life cycle is complete
Pathology:
1) larvae produces expanding cysts, esp. liver &/or lungs
2) cysts (hydatid cysts) may involve any organ
a) bone (invasion of medulla; pathologic fractures)
b) central nervous system (space-occupying lesions)
c) heart (conduction defects; pericarditis)
d) liver
Clinical manifestations:
1) depends upon size & location of cysts & amount of tissue destruction
2) often 5-20 years elapses before cysts are of sufficient size to cause symptoms
3) anaphylaxis may result from rupture of cyst fluid into pleural or peritoneal cavities
4) compression of a bile duct or leakage of cysts fluid into the biliary tree may mimic recurrent cholelithiasis
5) abdominal pain or right upper quadrant palpable mass may occur with hepatic echinococcosis
6) fever, pruritus or urticaria may occur with leakage or rupture of cysts
Laboratory:
1) eosinophilia is infrequent
2) skin testing (Casoni antigen)
3) serology: serum Echinococcus antibody
4) fine-needle aspiration of cyst fluid
a) presence of scoliceal hooklets
b) NOT routinely recommended; risk of fluid leakage
1] dissemination of infection
2] anaphlaxis
5) see ARUP consult [3]
Radiology:
- demonstration of cysts
a) CT of abdomen
b) MRI of abdomen
Management:
1) surgical excision, when feasible
a) definitive treatment
b) risks of dissemination of infection &/or anaphlaxis
- minimize risk with hypertonic saline or ethanol
2) albendazole
a) in conjunction with surgery
b) as medical management
- 400 mg BID for 28 days, repeated up to 8 times, separated by drug-free intervals of 2-3 weeks
3) prophylaxis
a) praziquantel treatment of infected dogs
b) denying dogs access to butchering sites or scraps from infected animals
Related
Echinococcus antibody in serum
Echinococcus granulosus
Echinococcus multilocularis
Echinococcus vogeli
hydatid cyst; echinococcal cyst
General
helminth infection
References
- DeGowin & DeGowin's Diagnostic Examination, 6th edition,
RL DeGowin (ed), McGraw Hill, NY 1994, pg 932
- Harrison's Principles of Internal Medicine, 13th ed.
Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 932
- ARUP Consult: Echinococcus Species - Echinococcus
The Physician's Guide to Laboratory Test Selection & Interpretation
https://www.arupconsult.com/content/echinococcus-species
- Murali MR, Uyeda JW, Tingpej B.
Case records of the Massachusetts General Hospital. Case 2-2015.
A 25-year-old man with abdominal pain, syncope, and hypotension.
N Engl J Med. 2015 Jan 15;372(3):265-73
PMID: 25587951
http://www.nejm.org/doi/full/10.1056/NEJMcpc1410939