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Christine Ahn MD
Carl Allen DDS, MSD
Brandon Ayres MD
Howard P. Baden MD
Robert Baran MD
Keira Barr MD
Gregory J. Basura MD, Ph.D
Donald Belsito MD
Jeffrey D. Bernhard MD
Jesse Berry MD
Victor Blanco MD
Benjamin R. Bohaty MD
William Bonnez MD
Sarah Brenner MD
Robert A. Briggaman MD
Robert Brodell MD
Roman Bronfenbrener MD
Walter Brooks MD
William Buckley MD
Philip Bulterys MD, PhD (candidate)
Susan Burgin MD
Sonya Burton MD
Sean P. Bush MD, FACEP
Jeffrey Callen MD
Scott Camazine MD
Michael Cardwell
Shelley D. Cathcart MD
Robert Chalmers MD, MRCP, FRCP
Chia-Yu Chu MD, PhD
Flavio Ciferri MD
Maria Rosa Cordisco MD
Noah Craft MD, PhD
John T. Crissey MD
Harold E. Cross MD, PhD
Charles Crutchfield III MD
Adriana Cruz MD
Donna Culton MD, PhD
Bart J. Currie MBBS, FRACP, DTM&H
Chicky Dadlani MD
Alexander Dane DO
C. Ralph Daniel III MD
Thomas Darling MD, PhD
William Delaney MD
Damian P. DiCostanzo MD
Ncoza Dlova MD
James Earls MD
Libby Edwards MD
Melissa K. Egge MD
Charles N. Ellis MD
Rachel Ellis MD
David Elpern MD
Nancy Esterly MD
Stephen Estes MD
E. Dale Everett MD
Janet Fairley MD
David Feingold MD
Benjamin Fisher MD
Henry Foong MBBS, FRCP
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Brian D. Foy PhD
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Bernardo Gontijo MD, PhD
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Jason E. Hawkes MD
Peter W. Heald MD
David G. Hicks MD
Sarah Hocker DO
Ryan J. Hoefen MD, PhD
Li-Yang Hsu MD
William Huang MD
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Carl Krucke
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Sue Lewis-Jones FRCP, FRCPCH
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Adam Lipworth MD
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Am. Journal of Trop. Med & Hygiene
Armed Forces Pest Management Board
Blackwell Publishing
Bugwood Network
Centers For Disease Control and Prevention
Centro Internacional de Entrenamiento e Investigaciones Mèdicas (CIDEIM)
Dermatology Online Journal
East Carolina University (ECU), Division of Dermatology
Echinococcosis, or hydatid disease, is a zoonotic parasitic (tapeworm) infection caused by the larval stage (metacestode) of species of the genus Echinococcus, mainly Echinococcusgranulosus (the northern biotype species is now recognized as Echinococcus canadensis) and Echinococcusmultilocularis, each of which leads to a different clinical presentation: cystic echinococcosis (CE) and alveolar echinococcosis (AE), respectively. A few other species, ie, Echinococcusortleppi, Echinococcusvogeli and Echinococcusoligarthrus, are very rarely found in humans and will not be covered in this section.
CE is the most common cause of hydatid disease; it involves a definitive host (dog) and an intermediate herbivorous animal (sheep, cattle). Humans may accidentally become infected through ingestion of food or water contaminated with eggs, or from contact with the fur of an infected dog. CE leads to slowly growing hepatic (70%) and/or pulmonary (20%) cystic lesions that can be asymptomatic for a variable time period (5-20 years). Cysts may be complicated by bacterial superinfection, cyst rupture, and anaphylactic shock.
AE involves wolves and dogs as definitive hosts and mice as intermediate hosts, with humans becoming infected through fecal-oral contact. AE is also a slowly advancing infection, although after a variable incubation period of 5-15 years, it differentiates itself from CE by producing multiple small vesicles infecting the liver initially, with subsequent metastatic spread to other organs (lungs, brain, bone, etc) in 20%-30% of cases. AE may be fatal if not treated.
CE has a nearly worldwide geographical distribution, although most cases reported in the United States are imported from European Mediterranean countries, the Russian Federation, China, Africa, Australia, and South America. AE is restricted to the northern hemisphere, with cases reported from Alaska and Canada in North America; Switzerland, Germany, and France in Europe; the tundra region of the Russian Federation; and the northern parts of China and Japan.
The initial phase of both CE and AE infection is asymptomatic. Cysts may grow slowly over months or even years. The infection may become symptomatic if the cysts either rupture or exert mass effect.
For liver involvement, abdominal pain and jaundice may occur with large cysts distending the liver capsule or compressing the biliary tree, while signs and symptoms of cholangitis or even anaphylaxis may present if cysts rupture.
For lung involvement, dyspnea can occur with large cyst(s) compressing lung parenchyma, while fever and cough productive of "salty" sputum may be the presenting signs of pulmonary cyst rupture.
The clinical presentation of the less common locations (ie, brain, bone, cardiac, or renal) is usually caused by mass effect.
Some patients may develop immunologic manifestations, such as urticaria or eosinophilia, in response to leakage of cyst contents. This can occur at any point during the course of the infection.
Infection can be life-threatening in special situations (anaphylaxis) and in advanced cases, but by and large echinococcosis is a chronic condition.
Codes
ICD10CM: B67.90 – Echinococcosis, unspecified
SNOMEDCT: 74942003 – Echinococcosis
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Differential Diagnosis & Pitfalls
Echinococcosis differential diagnosis depends mainly on the location of the cyst(s).
