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| {{CMG}} '''Associate Editor-In-Chief:''' {{CZ}} | | {{CMG}} '''Associate Editor-In-Chief:''' {{CZ}} |
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| {{SK}} Hydatid disease; hydatid cyst; unilocular hydatid disease; cystic echinococcosis | | {{SK}} Hydatid disease; hydatid cyst; unilocular hydatid disease; cystic echinococcosis |
| ==Overview== | | ==[[Echinococcosis overview|Overview]]== |
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| '''Echinococcosis''', also known as '''hydatid disease''', '''hydatid cyst''', '''unilocular hydatid disease''' or '''cystic echinococcosis''', is a potentially fatal [[parasitic disease]] that can affect many [[animal]]s, including [[wildlife]], commercial livestock and [[human]]s. The disease results from infection by [[tapeworm]] [[larva]]e of the [[genus]] ''[[Echinococcus]]'' - notably ''[[Echinococcus granulosus|E. granulosus]]'', ''[[Echinococcus multilocularis|E. multilocularis]]'', and ''Echinococcus vogeli''.
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| ==Infection cycle==
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| Like many other parasite infections, the course of Echinococcus infection is complex. The worm has a life cycle that requires ''definitive hosts'' and ''intermediate hosts''. Definitive hosts are normally carnivores such as dogs, while intermediate hosts are usually [[herbivores]] such as sheep and cattle. Humans also function as intermediate hosts, although they are usually a 'dead end' for the parasitic infection cycle.
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| The disease cycle begins with an adult tapeworm infecting the [[intestine|intestinal tract]] of the definitive host. The adult tapeworm then produces eggs which are expelled in the host's [[feces]]. Intermediate hosts become infected by ingesting the [[egg (biology)|eggs]] of the parasite. Inside the intermediate host, the eggs hatch and release tiny hooked [[embryo]]s which travel in the bloodstream, eventually lodging in an organ such as the [[liver]], [[lung]]s and/or [[kidneys]]. There, they develop into hydatid [[cyst]]s. Inside these cysts grow thousands of tapeworm larvae, the next stage in the life cycle of the parasite. When the intermediate host is predated or scavenged by the definitive host, the larvae are eaten and develop into [[adult]] tapeworms, and the infection cycle restarts.
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| ==Disease symptoms==
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| As already noted, ''Echinococcus'' infection causes large cysts to develop in intermediate hosts. Disease symptoms arise as the cysts grow bigger and start eroding and/or putting pressure on blood vessels and organs. Large cysts can also cause [[shock (medical)|shock]] if they happen to rupture.
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| Infection with ''E. granulosus'', common in Mediterranean countries, typically results in the formation of hydatid [[cyst]]s in the liver, lungs, kidney and [[spleen]] of the intermediate host. In echography or [[CT scan]]s, hydatid cysts are often large with a flaky appearance (this is referred to as "hydatid sand"); this indicates the first stage of infection. In the second stage, medical imaging may show multiple daughter cysts. Hydatid cyst of liver can be accurately diagnosed by a [[serology|serologic]] assay (Weinberg reaction). However, the Weinberg reaction is falsely negative in as many as 50% of people with cysts. [[Eosinophilia]] is not a feature of cysts unless rupture occurs. In fact, usually there are no changes in blood biochemistry.
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| [[Image:Hydatid sand.JPG|thumb|left|Echinococcus organisms taken from a hydatid cyst]]
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| Hydatid disease of lung or liver is generally asymptomatic but can cause serious complications if rupture of cyst occur. Systemic anaphylaxis is usually associated with cyst rupture and can be predicted by positivity of Casoni reaction. There is also risk of intrapleural or intraperitoneal dissemination of the disease and of secondary infection that causes a lung or hepatic [[abscess]]. This condition is also known as ''cystic hydatid disease'' and can sometimes be successfully treated with [[surgery]] to remove the cysts. In Portugal there is also some experience with PAIR (Percutaneous Aspiration, Infusion of scolicidal agents and Reaspiration of cyst content) and medical therapy with [[albendazole]] alone in the dose of 400 mg twice daily. Therapy with albendazole or [[praziquantel]] should be initiated before any procedure and prolonged 28 days if dissemination of hydatid cyst is to be avoided.
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| Infection with ''E. multilocularis'' results in the formation of dense parasitic [[tumor]]s in the liver, lungs, brain and other organs.Sometimes the infection in brain may cause tumour like symptoms and it needs removal by surgical means. [http://www.youtube.com/watch?v=AfNWBo1toY0]. This condition, also called ''alveolar hydatid disease'' is more likely to be fatal.
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| Infection with Echinococcus vogeli, restricted to Central and South America is characterized by polycystic disease.
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| Unlike intermediate hosts, definitive hosts are usually not hurt very much by the infection. Sometimes, a lack of certain vitamins and minerals can be caused in the host by the very high demand of the parasite.
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| [[Image:hydatid_cyst_membrane.jpg|thumb|left|appearance of a typical cyst at removal]]
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| '''Patient #1'''
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| <gallery>
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| Hydatid-cyst-001.jpg
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| Hydatid-cyst-002.jpg
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| </gallery>
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| '''Patient #2'''
| | ==[[Echinococcosis historical perspective|Historical Perspective]]== |
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| <gallery>
| | ==[[Echinococcosis classification|Classification]]== |
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| Echinococcus-001.jpg
| | ==[[Echinococcosis pathophysiology|Pathophysiology]]== |
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| | ==[[Echinococcosis causes|Causes]]== |
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| Echinococcus-002.jpg
| | ==[[Echinococcosis differential diagnosis|Differentiating Echinococcosis from other Diseases]]== |
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| | ==[[Echinococcosis epidemiology and demographics|Epidemiology and Demographics]]== |
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| Echinococcus-003.jpg
| | ==[[Echinococcosis risk factors|Risk Factors]]== |
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| | ==[[Echinococcosis natural history, complications and prognosis|Natural History, Complications and Prognosis]]== |
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| Echinococcus-004.jpg
| | ==Diagnosis== |
| | | [[Echinococcosis history and symptoms| History and Symptoms]] | [[Echinococcosis physical examination | Physical Examination]] | [[Echinococcosis laboratory findings|Laboratory Findings]] | [[Echinococcosis ultrasound|Ultrasound]] | [[Echinococcosis CT|CT]] | [[Echinococcosis MRI|MRI]] | [[Echinococcosis other diagnostic studies|Other Diagnostic Studies]] |
| </gallery>
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| ==Prophylaxis== | |
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| There are several strategies to prevent echinococcosis, most of which involve disruption of the parasite's life cycle. For instance, feeding raw offal to work dogs is a key point of infection in a farm environment and is strongly discouraged. Also, basic hygiene practices such as thoroughly cooking food and vigorous hand washing before meals can prevent the eggs entering the human digestive tract.
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| Regular "worming" of farm dogs with the drug [[praziquantel]] also helps kill the tapeworm. By employing such simple practices, hydatids have been virtually eliminated in New Zealand, where it was once very common. Effective [[vaccine]]s, based on [[recombinant DNA]] technology, are being developed in Australia for sheep.
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| ==Investigations==
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| * Blood CP
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| * Serology
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| * Casoni's Reaction
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| * Abdominal [[X-Ray]]
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| * [[Ultrasonography]] and [[CT]] Scanning
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| * [[ERCP]] (Endoscopic retrograde Cholangio-Pancreatography)
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| ==Treatment== | | ==Treatment== |
| * [[Metronidazole]] 400-600mg
| | [[Echinococcosis medical therapy|Medical Therapy]] | [[Echinococcosis surgery|Surgery]] | [[Echinococcosis primary prevention|Primary Prevention]] |
| * [[Albendazole]]
| | ==Case Studies== |
| * [[Surgical]]
| | [[Echinococcosis case study one|Case#1]] |
| :* Aspiration
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| :* Marsupialization
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| :* Omentopexy
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| :* Laminated Membrane Removal
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| :* [[Mebendazole]] to prevent recurrence
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| ==References== | |
| 1.Gottstein B, Reichen J. Echinococcosis/hydatidosis. | |
| In: Cook GC, ed. Manson’s tropical diseases,
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| 20th ed. London: Saunders; 1996:1486–508.
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| 2. Sailer M, Soelder B, Allerberger F, Zaknun D,
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| Feichtinger H, Gottstein B. Alveolar
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| echinococcosis in a six-year-old girl with AIDS.
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| 3.Reuter S, Schirrmeister H, Kratzer W, Dreweck C,Reske SN, Kern P. Pericystic metabolic activity in
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| alveolar echinococcosis: assessment and
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| follow-up by positron emission tomography.
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| Clin Inf Dis 1999;29:1157–63.
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| {{Helminthiases}} | | {{Helminthiases}} |
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