View source for Echinococcosis

{{Short description|Parasitic disease of tapeworms of the Echinococcus type}}
{{About|the disease|the organism|Echinococcus}}
{{Use dmy dates|date=December 2020}}
{{Infobox medical condition (new)
| name            = Echinococcosis
| synonyms        = Hydatid disease, hydatidosis, echinococcal disease, hydatid cyst
| image           = Echinococcus Life Cycle.svg
| caption         = ''Echinococcus granulosa'' life cycle (click to enlarge)
| field           = [[Infectious disease (medical specialty)|Infectious disease]]
| symptoms        = Variable<ref name=WHO2014/>
| complications   =
| onset           =
| duration        =
| causes          = [[Tapeworm]] of the ''[[Echinococcus]]'' type<ref name=WHO2014/>
| risks           =
| diagnosis       = [[Medical imaging]], blood tests<ref name=WHO2014/>
| differential    =
| prevention      = Vaccination of sheep, treating infected dogs<ref name=WHO2014/>
| treatment       = [[conservative treatment|Conservative]], medications, surgery<ref name=WHO2014/><ref name=CDCTx2013/>
| medication      = [[Albendazole]]<ref name=WHO2014/>
| prognosis       =
| frequency       = 1.4&nbsp;million (cystic form, 2015)<ref name=GBD2015Pre>{{cite journal|last1=GBD 2015 Disease and Injury Incidence and Prevalence|first1=Collaborators.|title=Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015.|journal=Lancet|date=8 October 2016|volume=388|issue=10053|pages=1545–1602|pmid=27733282|doi=10.1016/S0140-6736(16)31678-6|pmc=5055577}}</ref>
| deaths          = 1,200 (cystic form, 2015)<ref name=GBD2015De/>
}}
<!-- Definition and symptoms -->
'''Echinococcosis''' is a [[parasitic disease]] of [[tapeworm]]s of the ''[[Echinococcus]]'' type.<ref name=WHO2014/> The two [[Portal:Main|main]] types of the disease are ''cystic echinococcosis'' and ''[[alveolar echinococcosis]]''.<ref name=WHO2014/> Less common forms include ''polycystic echinococcosis'' and ''unicystic echinococcosis''.<ref name=WHO2014/>

The disease often starts without symptoms and this may last for years.<ref name=WHO2014/> The symptoms and signs that occur depend on the cyst's location and size.<ref name=WHO2014/> ''Alveolar'' disease usually begins in the liver, but can spread to other parts of the body, such as the lungs or brain.<ref name=WHO2014/> When the [[liver]] is affected, the patient may experience [[abdominal pain]], weight loss, along with yellow-toned skin discoloration from developed [[jaundice]].<ref name=WHO2014/> Lung disease may cause pain in the chest, [[shortness of breath]], and coughing.<ref name=WHO2014>{{cite web|title=Echinococcosis Fact sheet N°377|url=https://www.who.int/mediacentre/factsheets/fs377/en/|work=World Health Organization|access-date=19 March 2014|date=March 2014|url-status=live|archive-url=https://web.archive.org/web/20140221184309/http://www.who.int/mediacentre/factsheets/fs377/en/|archive-date=21 February 2014}}</ref>

<!-- Cause -->
The infection is spread when food or water that contains the eggs of the parasite is ingested or by close contact with an infected animal.<ref name=WHO2014/> The eggs are released in the stool of meat-eating animals that are infected by the parasite.<ref name=CDC2013>{{cite web|title=Echinococcosis [Echinococcus granulosus] [Echinococcus multilocularis] [Echinococcus oligarthrus] [Echinococcus vogeli]|url=https://www.cdc.gov/dpdx/echinococcosis/index.html|work=CDC|access-date=20 March 2014|date=29 November 2013|url-status=live|archive-url=https://web.archive.org/web/20140320100116/http://www.cdc.gov/dpdx/echinococcosis/index.html|archive-date=20 March 2014}}</ref> Commonly infected animals include dogs, foxes, and wolves.<ref name=CDC2013/> For these animals to become infected they must eat the [[organ (anatomy)|organs]] of an animal that contains the cysts such as sheep or rodents.<ref name=CDC2013/> The type of disease that occurs in human patients depends on the type of ''Echinococcus'' causing the infection.<ref name=WHO2014/> Diagnosis is usually by [[ultrasound]] though [[computer tomography]] (CT) or [[magnetic resonance imaging]] (MRI) may also be used.<ref name=WHO2014/> Blood tests looking for [[antibodies]] against the parasite may be helpful as may [[biopsy]].<ref name=WHO2014/>

<!-- Prevention and Treatment -->
Prevention of cystic disease is by treating dogs that may carry the disease and vaccination of sheep.<ref name=WHO2014/> Treatment is often difficult.<ref name=WHO2014/> The cystic disease may be drained through the skin, followed by medication.<ref name=WHO2014/> Sometimes this type of disease is just watched.<ref name=CDCTx2013>{{cite web|title=Echinococcosis Treatment Information|url=https://www.cdc.gov/dpdx/echinococcosis/tx.html|work=CDC|access-date=20 March 2014|date=29 November 2013|url-status=live|archive-url=https://web.archive.org/web/20140320100026/http://www.cdc.gov/dpdx/echinococcosis/tx.html|archive-date=20 March 2014}}</ref> The ''alveolar''  form often requires surgical intervention, followed by medications.<ref name=WHO2014/> The medication used is [[albendazole]], which may be needed for years.<ref name=WHO2014/><ref name=CDCTx2013/> The ''alveolar''  disease may result in death.<ref name=WHO2014/>

<!-- Epidemiology -->
The disease occurs in most areas of the world and currently affects about one million people.<ref name=WHO2014/> In some areas of South America, Africa, and Asia, up to 10% of the certain populations are affected.<ref name=WHO2014/> In 2015, the cystic form caused about 1,200 deaths; down from 2000 in 1990.<ref name=GBD2015De>{{cite journal|last1=GBD 2015 Mortality and Causes of Death|first1=Collaborators.|title=Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980–2015: a systematic analysis for the Global Burden of Disease Study 2015.|journal=Lancet|date=8 October 2016|volume=388|issue=10053|pages=1459–1544|pmid=27733281|doi=10.1016/s0140-6736(16)31012-1|pmc=5388903}}</ref><ref name=Loz2012>{{cite journal|last=Lozano|first=R|title=Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010.|journal=Lancet|date=15 December 2012|volume=380|issue=9859|pages=2095–128|pmid=23245604|doi=10.1016/S0140-6736(12)61728-0|hdl=10536/DRO/DU:30050819|s2cid=1541253|url=https://zenodo.org/record/2557786|hdl-access=free}}</ref> The economic cost of the disease is estimated to be around US$3 billion a year.<ref name=WHO2014/> It is classified as a [[neglected tropical disease]] (NTD) and belongs to the group of diseases known as [[helminthiases]] (worm infections).<ref name=NTD2017>{{cite web|title=Neglected Tropical Diseases|url=https://www.cdc.gov/globalhealth/ntd/diseases/index.html|website=cdc.gov|access-date=28 November 2014|date=6 June 2011|url-status=live|archive-url=https://web.archive.org/web/20141204084219/http://www.cdc.gov/globalhealth/ntd/diseases/index.html|archive-date=4 December 2014}}</ref> It can affect other animals such as pigs, cows and horses.<ref name=WHO2014/>

<!-- Terminology-->
Terminology used in this field is crucial, since ''echinococcosis'' requires the involvement of specialists from nearly all disciplines. In 2020, an international effort of scientists, from 16 countries, lead to a detailed consensus on terms to be used or rejected for the genetics, epidemiology, biology, immunology and clinical aspects of ''echinococcosis''.<ref name="VuittonMcManus2020">{{cite journal|last1=Vuitton|first1=Dominique A.|last2=McManus|first2=Donald P.|last3=Rogan|first3=Michael T.|last4=Romig|first4=Thomas|last5=Gottstein|first5=Bruno|last6=Naidich|first6=Ariel|last7=Tuxun|first7=Tuerhongjiang|last8=Wen|first8=Hao|last9=Menezes da Silva|first9=Antonio|last10=Vuitton|first10=Dominique A.|last11=McManus|first11=Donald P.|last12=Romig|first12=Thomas|last13=Rogan|first13=Michael R.|last14=Gottstein|first14=Bruno|last15=Menezes da Silva|first15=Antonio|last16=Wen|first16=Hao|last17=Naidich|first17=Ariel|last18=Tuxun|first18=Tuerhongjiang|last19=Avcioglu|first19=Amza|last20=Boufana|first20=Belgees|last21=Budke|first21=Christine|last22=Casulli|first22=Adriano|last23=Güven|first23=Esin|last24=Hillenbrand|first24=Andreas|last25=Jalousian|first25=Fateme|last26=Jemli|first26=Mohamed Habib|last27=Knapp|first27=Jenny|last28=Laatamna|first28=Abdelkarim|last29=Lahmar|first29=Samia|last30=Naidich|first30=Ariel|last31=Rogan|first31=Michael T.|last32=Sadjjadi|first32=Seyed Mahmoud|last33=Schmidberger|first33=Julian|last34=Amri|first34=Manel|last35=Bellanger|first35=Anne-Pauline|last36=Benazzouz|first36=Sara|last37=Brehm|first37=Klaus|last38=Hillenbrand|first38=Andreas|last39=Jalousian|first39=Fateme|last40=Kachani|first40=Malika|last41=Labsi|first41=Moussa|last42=Masala|first42=Giovanna|last43=Menezes da Silva|first43=Antonio|last44=Sadjjadi Seyed|first44=Mahmoud|last45=Soufli|first45=Imene|last46=Touil-Boukoffa|first46=Chafia|last47=Wang|first47=Junhua|last48=Zeyhle|first48=Eberhard|last49=Aji|first49=Tuerganaili|last50=Akhan|first50=Okan|last51=Bresson-Hadni|first51=Solange|last52=Dziri|first52=Chadli|last53=Gräter|first53=Tilmann|last54=Grüner|first54=Beate|last55=Haïf|first55=Assia|last56=Hillenbrand|first56=Andreas|last57=Koch|first57=Stéphane|last58=Rogan|first58=Michael T.|last59=Tamarozzi|first59=Francesca|last60=Tuxun|first60=Tuerhongjiang|last61=Giraudoux|first61=Patrick|last62=Torgerson|first62=Paul|last63=Vizcaychipi|first63=Katherina|last64=Xiao|first64=Ning|last65=Altintas|first65=Nazmiye|last66=Lin|first66=Renyong|last67=Millon|first67=Laurence|last68=Zhang|first68=Wenbao|last69=Achour|first69=Karima|last70=Fan|first70=Haining|last71=Junghanss|first71=Thomas|last72=Mantion|first72=Georges A.|title=International consensus on terminology to be used in the field of echinococcoses|journal=Parasite|volume=27|year=2020|pages=41|issn=1776-1042|doi=10.1051/parasite/2020024|url= |pmid=32500855|pmc=7273836|doi-access=free}} {{open access}}</ref>

==Signs and symptoms==
[[File:Parasite180022-4-olm Cystic echinococcosis in a cat.ogg|thumb|Removal of cysts (here, from a definitive host, a cat)]]
[[Image:Cotton rat infected with Echinococcus multilocularis 3MG0020 lores.jpg|thumb|Cysts in a [[cotton rat]]]]
[[Image:Laminated liver cyst wall - high mag.jpg|thumb|[[Micrograph]] showing the characteristic laminated cyst wall.[[H&E stain]].]]

In the human manifestation of the disease, ''E. granulosus'', ''E. multilocularis'', ''E. oligarthrus'' and ''E. vogeli'' are localized in the liver (in 75% of cases), the lungs (in 5–15% of cases) and other organs in the body such as the spleen, brain, heart, and kidneys (in 10–20% of cases). In people who are infected with ''E. granulosus'' and therefore have cystic echinococcosis, the disease develops as a slow-growing mass in the body. These slow-growing masses, often called cysts, are also found in people that are infected with alveolar and polycystic echinococcosis.{{cn|date=May 2021}}

The cysts found in those with cystic echinococcosis are usually filled with a clear fluid called hydatid fluid, are spherical, and typically consist of one compartment and are usually only found in one area of the body. While the cysts found in those with alveolar and polycystic echinococcosis are similar to those found in those with cystic echinococcosis, the alveolar and polycystic echinococcosis cysts usually have multiple compartments and have infiltrative as opposed to expansive growth.<ref name="TappeDennis" /><ref>{{cite journal |vauthors=Canda MS, Canda T, Astarcioglu H, Güray M |title=The Pathology of Echinococcosis and the Current Echinococcosis Problem in Western Turkey |journal=Turk J Med Sci |volume=33 |pages=369–374 |year=2003 |url=http://journals.tubitak.gov.tr/medical/issues/sag-03-33-6/sag-33-6-5-0209-8.pdf |url-status=live |archive-url=https://web.archive.org/web/20110928075250/http://journals.tubitak.gov.tr/medical/issues/sag-03-33-6/sag-33-6-5-0209-8.pdf |archive-date=28 September 2011  }}</ref>

Depending on the location of the cyst in the body, the person could be asymptomatic even though the cysts have grown to be very large, or be symptomatic even if the cysts are absolutely tiny. If the person is symptomatic, the symptoms will depend largely on where the cysts are located. For instance, if the person has cysts in the lungs and is symptomatic, they will have a cough, shortness of breath and/or pain in the chest.{{cn|date=May 2021}}

On the other hand, if the person has cysts in the liver and is symptomatic, they will suffer from abdominal pain, abnormal abdominal tenderness, hepatomegaly with an abdominal mass, jaundice, fever and/or anaphylactic reaction. In addition, if the cysts were to rupture while in the body, whether during surgical extraction of the cysts or by trauma to the body, the person would most likely go into anaphylactic shock and suffer from high fever, pruritus (itching), edema (swelling) of the lips and eyelids, dyspnea, stridor and rhinorrhea.<ref>{{cite journal |vauthors=Bitton M, Kleiner-Baumgarten A, Peiser J, Barki Y, Sukenik S |title=Anaphylactic shock after traumatic rupture of a splenic echinococcal cyst |language=he |journal=Harefuah |volume=122 |issue=4 |pages=226–8 |date=February 1992 |pmid=1563683 }}</ref>

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.{{citation needed|date=July 2020}}

The incubation period for all species of ''Echinococcus'' can be months to years, or even decades.<ref>{{cite journal |vauthors=Kemp C, Roberts A |title=Infectious diseases: echinococcosis (hydatid disease) |journal=J Am Acad Nurse Pract |volume=13 |issue=8 |pages=346–7 |date=August 2001 |pmid=11930567 |doi=10.1111/j.1745-7599.2001.tb00047.x}}</ref> It largely depends on the location of the cyst in the body and how fast the cyst is growing.<ref name=Eckert04 />

==Cause==
Also like many other parasite infections, the course of ''Echinococcus'' infection is complex. The worm has a life cycle that requires [[intermediate host|definitive hosts]] and [[intermediate host]]s. Definitive hosts are normally [[carnivores]] such as dogs, while intermediate hosts are usually [[herbivores]] such as sheep and cattle. Humans function as accidental
hosts, because they are usually a dead end for the parasitic infection cycle.{{cn|date=May 2021}}

===Hosts===
[[File:Renardrouxcampagnol.jpg|thumb|Red fox with rodent]]
{| class="wikitable"
|-
! Organism !! Definitive Hosts!! Intermediate Hosts
|-
|''E. granulosus''|| dogs and other canidae || sheep, goats, cattle, camel, buffalo, swine, kangaroos, and other wild herbivores
|-
|''E. multilocularis''|| foxes, dogs, other canidae and cats || small rodents
|-
|''E. vogeli''|| bush dogs and dogs || rodents
|-
|''E. oligarthrus''||wild felids<ref name="dpd" /><ref name="Sréter03"/> || small rodents<ref name="dpd" /><ref name="Sréter03" />
|}

===Life cycle===
An adult worm resides in the small intestine of a definitive host. A single gravid proglottid releases eggs that are passed in the feces of the definitive host.  The egg is then ingested by an intermediate host. The egg then hatches in the small intestine of the intermediate host and releases an oncosphere that penetrates the intestinal wall and moves through the circulatory system into different organs, in particular the liver and lungs. Once it has invaded these organs, the oncosphere develops into a cyst. The cyst then slowly enlarges, creating protoscolices (juvenile [[Cestoda#Scolex|scolices]]), and daughter cysts within the cyst. The definitive host then becomes infected after ingesting the cyst-containing organs of the infected intermediate host. After ingestion, the protoscolices attach to the intestine. They then develop into adult worms and the cycle starts all over again.{{citation needed|date=July 2020}}

===Eggs===
[[Image:Echinococcus Egg.jpg|thumb|''Echinococcus'' egg in feces]]
[[Image:Echinococcus Proscolices.jpg|thumb|Protoscolices being released from a hydatid cyst]]
''Echinococcus'' eggs contain an embryo that is called an [[oncosphere]] or hexcanth. The name of this embryo stems from the fact that these embryos have six hooklets. The eggs are passed through the feces of the definitive host and it is the ingestion of these eggs that lead to infection in the intermediate host.<ref name="JohnDavid" />

===Larval/hydatid cyst stage===
From the embryo released from an egg develops a ''hydatid cyst'', which grows to about 5–10&nbsp;cm within the first year and is able to survive within organs for years.<ref>{{cite book |chapter=Ch. 290 |editor1-first=Gerald L. |editor1-last=Mandell |editor2-first=John Eugene |editor2-last=Bennett |editor3-first=Raphael |editor3-last=Dolin |title=Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases |publisher=Elsevier |year=2010 |isbn=978-0443068393 |edition=7th}}</ref> Cysts sometimes grow to be so large that by the end of several years or even decades, they can contain several liters of fluid. Once a cyst has reached a diameter of 1&nbsp;cm, its wall differentiates into a thick outer, non-cellular membrane, which covers the thin germinal epithelium. From this epithelium, cells begin to grow within the cyst. These cells then become vacuolated, and are known as brood capsules, which are the parts of the parasite from which protoscolices bud. Often, daughter cysts also form within cysts.<ref name="JohnDavid" />

===Adult worm===
''Echinococcus'' adult worms develop from protoscolices and are typically 6&nbsp;mm or less in length and have a scolex, neck and typically three proglottids, one of which is immature, another of which is mature and the third of which is gravid (or containing eggs).<ref name="JohnDavid" /> The scolex of the adult worm contains four suckers and a [[Rostellum (helminth)|rostellum]] that has about 25–50 hooks.<ref>{{cite web |title=Echinococcosis |date= 17 April 2019|work=DPDx. Parasite Image Library |publisher=CDC |url=http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Echinococcosis_il.htm |url-status=live |archive-url=https://web.archive.org/web/20100304141540/http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Echinococcosis_il.htm |archive-date=4 March 2010  }}</ref>

===Morphological differences===
The major morphological difference among different species of ''Echinococcus'' is the length of the tapeworm. ''E. granulosus'' is approximately 2 to 7&nbsp;mm while ''E. multilocularis'' is often smaller and is 4&nbsp;mm or less.<ref name=Eckert04>{{cite journal |vauthors=Eckert J, Deplazes P |title=Biological, epidemiological, and clinical aspects of echinococcosis, a zoonosis of increasing concern |journal=Clin. Microbiol. Rev. |volume=17 |issue=1 |pages=107–35 |date=January 2004 |pmid=14726458 |pmc=321468 |doi=10.1128/cmr.17.1.107-135.2004  }}</ref> On the other hand, ''E. vogeli'' is found to be up to 5.6&nbsp;mm long and ''E. oligarthrus'' is found to be up to 2.9&nbsp;mm long.<ref name="dpd" /> In addition to the difference in length, there are also differences in the hydatid cysts of the different species. For instance, in ''E. multilocularis'', the cysts have an ultra thin limiting membrane and the germinal epithelium may bud externally. Furthermore, ''E. granulosus'' cysts are unilocular and full of fluid while ''E. multilocularis'' cysts contain little fluid and are multilocular. For ''E. vogeli'', its hydatid cysts are large and are actually polycystic since the germinal membrane of the hydatid cyst actually proliferates both inward, to create septa that divide the hydatid into sections, and outward, to create new cysts. Like ''E. granulosus'' cysts, ''E. vogeli'' cysts are filled with fluid.<ref name="JohnDavid" />

===Transmission===
As one can see from the life cycles illustrated above, all disease-causing species of ''Echinococcus'' are transmitted to intermediate hosts via the ingestion of eggs and are transmitted to definitive hosts by means of eating infected, cyst-containing organs. Humans are accidental intermediate hosts that become infected by handling soil, dirt or animal hair that contains eggs.<ref name=Eckert04 />

While there are no biological or mechanical vectors for the adult or larval form of any ''Echinococcus'' species, coprophagic flies, carrion birds and arthropods can act as mechanical vectors for the eggs.<ref>{{cite web |title=''Echinococcus granulosus'' |date=2001 |work=Material Safety Data Sheets (MSDS) |publisher=Public Healthy Agency of Canada |url=http://www.phac-aspc.gc.ca/msds-ftss/msds54e-eng.php |url-status=live |archive-url=https://web.archive.org/web/20100305181917/http://www.phac-aspc.gc.ca/msds-ftss/msds54e-eng.php |archive-date=5 March 2010  }}</ref>

===Aberrant cases===
There are a few aberrant cases in which carnivores play the role of the intermediate hosts. Examples are domestic cats with hydatid cysts of ''E. granulosus.''<ref name="BonelliMasu2018">{{cite journal|last1=Bonelli|first1=Piero|last2=Masu|first2=Gabriella|last3=Giudici|first3=Silvia Dei|last4=Pintus|first4=Davide|last5=Peruzzu|first5=Angela|last6=Piseddu|first6=Toni|last7=Santucciu|first7=Cinzia|last8=Cossu|first8=Assunta|last9=Demurtas|first9=Nicola|last10=Masala|first10=Giovanna|title=Cystic echinococcosis in a domestic cat (''Felis catus'') in Italy|journal=Parasite|volume=25|year=2018|pages=25|issn=1776-1042|doi=10.1051/parasite/2018027|pmid=29727269|pmc=5935470}} {{open access}}</ref>

==Diagnosis==
[[File:Polycystic echinococcosis affecting the left side of the liver.jpg|thumbnail|right|Computed tomography (A) and magnetic resonance (B) images of the liver of a 72-year-old man from French Guiana with polycystic echinococcosis affecting the left side of the liver. White arrows indicate the multicystic liver lesion.]]
[[File:İndirekt Hemaglütinasyon Deneyi.jpg|thumb|Indirect hemagglutination assay for human echinococcosis. Different serum samples diluted from the left to the right. Seropositivity was suspected in Sample 179]]

===Classification===
The most common form found in humans is cystic echinococcosis (also known as unilocular echinococcosis), which is caused by ''[[Echinococcus granulosus sensu lato]]''. The second most common form is [[alveolar hydatid disease|alveolar echinococcosis]] (also known as alveolar colloid of the liver, alveolar hydatid disease, alveolococcosis, multilocular echinococcosis, "small fox tapeworm"), which is caused by ''[[Echinococcus multilocularis]]'' and the third is polycystic echinococcosis (also known as human polycystic hydatid disease, neotropical echinococcosis), which is caused by ''[[Echinococcus vogeli]]'' and very rarely, ''[[Echinococcus oligarthrus]]''. Alveolar and polycystic echinococcosis are rarely diagnosed in humans and are not as widespread as cystic echinococcosis, but polycystic echinococcosis is relatively new on the medical scene and is often left out of conversations dealing with echinococcosis, and alveolar echinococcosis is a serious disease that has not only a significantly high fatality rate, but the potential to become an emerging disease in many countries.{{cn|date=May 2021}}

===Cystic===
A formal diagnosis of any type of echinococcosis requires a combination of tools that involve imaging techniques, histopathology, or nucleic acid detection and serology. For cystic echinococcosis diagnosis, imaging is the main method—while serology tests (such as indirect hemogglutination, ELISA (enzyme linked immunosorbent assay), immunoblots or latex agglutination) that use antigens specific for ''E. granulosus'' verify the imaging results. The imaging technique of choice for cystic echinococcosis is ultrasonography, since it is not only able to visualize the cysts in the body's organs,<ref name="BrunettiEnrico">{{cite journal |vauthors=Brunetti E, Kern P, Vuitton DA |title=Expert consensus for the diagnosis and treatment of cystic and alveolar echinococcosis in humans |journal=Acta Trop. |volume=114 |issue=1 |pages=1–16 |date=April 2010 |pmid=19931502 |doi=10.1016/j.actatropica.2009.11.001 |doi-access=free }}</ref> but it is also inexpensive, non-invasive and gives instant results.<ref>{{cite journal |vauthors=Macpherson CN, Milner R |title=Performance characteristics and quality control of community based ultrasound surveys for cystic and alveolar echinococcosis |journal=Acta Trop. |volume=85 |issue=2 |pages=203–9 |date=February 2003 |pmid=12606098 |doi=10.1016/s0001-706x(02)00224-3}}</ref> In addition to ultrasonography, both MRI and CT scans can and are often used although an MRI is often preferred to CT scans when diagnosing cystic echinococcosis since it gives better visualization of liquid areas within the tissue.<ref name="BrunettiEnrico" />

===Alveolar===
As with cystic echinococcosis, ultrasonography is the imaging technique of choice for alveolar echinococcosis and is usually complemented by CT scans since CT scans are able to detect the largest number of lesions and calcifications that are characteristic of alveolar echinococcosis. MRIs are also used in combination with ultrasonography though CT scans are preferred. Like cystic echinococcosis, imaging is the major method used for the diagnosis of alveolar echinococcosis while the same types of serologic tests (except now specific for ''E. multilocularis'' antigens) are used to verify the imaging results. It is also important to note that serologic tests are more valuable for the diagnosis of alveolar echinococcosis than for cystic echinococcosis since they tend to be more reliable for alveolar echinococcosis since more antigens specific for ''E. multilocularis'' are available.<ref name=Eckert04 /> In addition to imaging and serology, identification of ''E. multilocularis'' infection via PCR or a histological examination of a tissue biopsy from the person is another way to diagnose alveolar echinococcosis.<ref name="BrunettiEnrico" />

===Polycystic===
Similar to the diagnosis of alveolar echinococcosis and cystic echinococcosis, the diagnosis of polycystic echinococcosis uses imaging techniques, in particular ultrasonography and CT scans, to detect polycystic structures within the person's body. However, imaging is not the preferred method of diagnosis since the method that is currently considered the standard is the isolation of protoscoleces during surgery or after the person's death and the identification of definitive features of ''E. oligarthrus'' and ''E. vogeli'' in these isolated protoscoleces. This is the main way that PE is diagnosed, but some current studies show that PCR may identify ''E. oligarthrus'' and ''E. vogeli'' in people's tissues.<ref>{{cite journal  |vauthors=Knapp J, Chirica M, Simonnet C, etal |title=''Echinococcus vogeli'' infection in a hunter, French Guiana |journal=Emerging Infect. Dis. |volume=15 |issue=12 |pages=2029–31 |date=December 2009 |pmid=19961693 |pmc=3044547 |doi=10.3201/eid1512.090940 }}</ref> The only drawback of using PCR to diagnose polycystic echinococcosis is that there aren't many genetic sequences that can be used for PCR that are specific only ''E. oligarthrus'' or ''E. vogeli''.<ref name=Eckert04 />

==Prevention==
[[File:Parasite140085-fig1 Boiling sheep livers containing hydatid cysts (Echinococcus granulosus).tif|thumb|Boiling sheep livers containing hydatid cysts for 30 minutes kills the cestode larvae – a simple method for prevention in remote areas<ref name="LiWu2014"/>]]

===Cystic echinococcosis===
There are several different strategies that are currently being used to prevent and control cystic echinococcosis (CE). Most of these various methods try to prevent and control CE by targeting the major risk factors for the disease and the way it is transmitted. For instance, health education programs focused on cystic echinococcosis and its agents, and improved water sanitation attempt to target poor education and poor drinking water sources, which are both risk factors for contracting echinococcosis. Furthermore, since humans often come into contact with ''Echinococcus'' eggs via touching contaminated soil, animal feces and animal hair, another prevention strategy is improved hygiene. In addition to targeting risk factors and transmission, control and prevention strategies of cystic echinococcosis also aim at intervening at certain points of the parasite's life cycle, in particular, the infection of hosts (especially dogs) that reside with or near humans. For example, many countries endemic to echinococcosis have implemented programs geared at de-worming dogs and vaccinating dogs and other livestock, such as sheep, that also act as hosts for ''E. granulosus''.{{cn|date=May 2021}}

Proper disposal of carcasses and offal after home slaughter is difficult in poor and remote communities and therefore dogs readily have access to offal from livestock, thus completing the parasite cycle of ''Echinococcus granulosus'' and putting communities at risk of cystic echinococcosis. Boiling livers and lungs that contain hydatid cysts for 30 minutes has been proposed as a simple, efficient and energy- and time-saving way to kill the infectious larvae.<ref name="LiWu2014">{{cite journal|last1=Li|first1=Jun|last2=Wu|first2=Chuanchuan|last3=Wang|first3=Hui|last4=Liu|first4=Huanyuan|last5=Vuitton|first5=Dominique A.|last6=Wen|first6=Hao|last7=Zhang|first7=Wenbao|title=Boiling sheep liver or lung for 30 minutes is necessary and sufficient to kill ''Echinococcus granulosus'' protoscoleces in hydatid cysts|journal=Parasite|volume=21|year=2014|pages=64|issn=1776-1042|doi=10.1051/parasite/2014064|pmid=25456565|pmc=4251422}}{{open access}}</ref>

===Alveolar echinococcosis===
A number of strategies are geared towards prevention and control of alveolar echinococcosis—most of which are similar to those for cystic echinococcosis. For instance, health education programs, improved water sanitation, improved hygiene and de-worming of hosts (particularly red foxes) are all effective to prevent and control the spread of alveolar echinococcosis. Unlike cystic echinococcosis, however, where there is a vaccine against ''E. granulosus'', there is currently no canidae or livestock vaccine against ''E. multilocularis''.<ref>{{cite journal  |vauthors=Craig PS, McManus DP, Lightowlers MW, etal |title=Prevention and control of cystic echinococcosis |journal=Lancet Infect Dis |volume=7 |issue=6 |pages=385–94 |date=June 2007 |pmid=17521591 |doi=10.1016/S1473-3099(07)70134-2 }}</ref>

===Polycystic echinococcosis===
While a number of control and prevention strategies deal with cystic and alveolar echinococcosis, there are few methods to control and prevent polycystic echinococcosis. This is probably due to the fact that polycystic echinococcosis is restricted to Central and South America, and that the way that humans become accidental hosts of ''E. oligarthrus'' and ''E. vogeli'' is still not completely understood.<ref name=Eckert04 />

===Human vaccines===
Currently there are no human vaccines against any form of echinococcosis. However, there are studies being conducted that are looking at possible vaccine candidates for an effective human vaccine against echinococcosis.<ref>{{cite journal  |vauthors=Dang Z, Yagi K, Oku Y, etal |title=Evaluation of ''Echinococcus multilocularis'' tetraspanins as vaccine candidates against primary alveolar echinococcosis |journal=Vaccine |volume=27 |issue=52 |pages=7339–45 |date=December 2009 |pmid=19782112 |doi=10.1016/j.vaccine.2009.09.045 |citeseerx=10.1.1.539.7799 }}</ref>

==Treatment==

===Cystic===
[[File:Vuitton et al - International consensus on terminology - parasite200043-fig3.png|thumb|left|International consensus on nomenclature framework for cystic echinococcosis surgery]]

For simple cases of cystic echinococcosis, the most common form of treatment is open surgical removal of the cysts combined with chemotherapy using [[albendazole]] and/or [[mebendazole]] before and after surgery. However, if there are cysts in multiple organs or tissues, or the cysts are in risky locations, surgery becomes impractical. For inoperable cases such as these, chemotherapy and/or [[PAIR (puncture-aspiration-injection-reaspiration)]] become alternative options of treatment.<ref name=Eckert04 /> In the case of alternative treatment using just chemotherapy, albendazole is preferred twice a day for 1–5 months.<ref name=DPDxTapeworm>{{cite web |title=The Medical Letter (Drugs for Parasitic Infections) |date=20 July 2009 |publisher=DPDx, CDC |url=http://www.dpd.cdc.gov/dpdx/hTML/PDF_Files/MedLetter/TapewormInfection.pdf |url-status=live |archive-url=https://web.archive.org/web/20100304174546/http://www.dpd.cdc.gov/dpdx/HTML/PDF_Files/MedLetter/TapewormInfection.pdf |archive-date=4 March 2010  }}</ref> An alternative to albendazole is mebendazole for at least 3 to 6 months. The other alternative to surgery is PAIR with chemotherapy. PAIR is a minimally invasive procedure that involves three steps: puncture and needle aspiration of the cyst, injection of a [[scolicidal]] solution for 20–30 min, and cyst-re-aspiration and final irrigation. People who undergo PAIR typically take albendazole or mebendazole from 7 days before the procedure until 28 days after the procedure.{{cn|date=May 2021}}

While open surgery still remains as the standard for cystic echinococcosis treatment, there have been a number of studies that suggest that PAIR with chemotherapy is more effective than surgery in terms of disease recurrence, and morbidity and mortality.<ref>{{cite journal |vauthors=Park KH, Jung SI, Jang HC, Shin JH |title=First successful puncture, aspiration, injection, and re-aspiration of hydatid cyst in the liver presenting with anaphylactic shock in Korea |journal=Yonsei Med. J. |volume=50 |issue=5 |pages=717–20 |date=October 2009 |pmid=19881979 |pmc=2768250 |doi=10.3349/ymj.2009.50.5.717 }}</ref> In addition to the three above mentioned treatments, there is currently research and studies looking at new treatment involving percutaneous thermal ablation (PTA) of the germinal layer in the cyst by means of a radiofrequency ablation device. This form of treatment is still relatively new and requires much more testing before being widely used.<ref name=Eckert04 /> An alternative to open surgery is laparoscopic surgery, which provides excellent cure rates with minimal morbidity and mortality.<ref>{{cite journal |author=Jani K |title=Spillage-free laparoscopic management of hepatic hydatid disease using the hydatid trocar canula |journal=J Minim Access Surg |volume=10 |issue=3 |pages=113–8 |date=July 2014 |pmid=25013326 |pmc=4083542 |doi=10.4103/0972-9941.134873 }}</ref>

===Alveolar===
For alveolar echinococcosis, surgical removal of cysts combined with chemotherapy (using albendazole and/or mebendazole) for up to two years after surgery is the only sure way to completely cure the disease.<ref name=DPDxTapeworm/> However, in inoperable cases, chemotherapy by itself can also be used. In treatment using just chemotherapy, one could use either mebendazole in three doses or albendazole in two doses. Since chemotherapy on its own is not guaranteed to completely rid of the disease, people are often kept on the drugs for extended periods of times (i.e. more than 6 months, years). In addition to surgery and chemotherapy, liver transplants are being looked into as a form of treatment for alveolar echinococcosis although it is seen as incredibly risky since it often leads to echinococcosis re-infection in the person afterwards.<ref name=Eckert04 />

===Polycystic===
Since polycystic echinococcosis is constrained to such a particular area of the world and is not well described or found in many people, treatment of polycystic echinococcosis is less defined than that of cystic and alveolar echinococcosis. While surgical removal of cysts was the treatment of choice for the previous two types of echinococcosis, chemotherapy is the recommended treatment approach for polycystic echinococcosis. While albendazole is the preferred drug, mebendazole can also be used if the treatment is to be for an extended period of time. Only if chemotherapy fails or if the lesions are very small is surgery advised.<ref name=Eckert04 />

==Epidemiology==
[[File:Populations at Risk for Alveolar Echinococcosis, France.jpg|thumb|Location of people, controls, and areas in France where persons are at risk for alveolar echinococcosis. See legend below the image.]]

=== Regions ===
Very few countries are considered to be completely free of ''E. granulosus''.<ref>{{cite journal |vauthors=Budke CM, Deplazes P, Torgerson PR |title=Global socioeconomic impact of cystic echinococcosis |journal=Emerging Infect. Dis. |volume=12 |issue=2 |pages=296–303 |date=February 2006 |pmid=16494758 |pmc=3373106 |doi=10.3201/eid1202.050499  }}</ref> Areas of the world where there is a high rate of infection often coincide with rural, grazing areas where dogs are able to ingest organs from infected animals.{{cn|date=May 2021}}

''E. multilocularis'' mainly occurs in the Northern hemisphere, including central Europe and the northern parts of Europe, Asia, and North America.<ref name="MassoloLiccioli2014">{{cite journal|last1=Massolo|first1=Alessandro|last2=Liccioli|first2=Stefano|last3=Budke|first3=Christine|last4=Klein|first4=Claudia|title=''Echinococcus multilocularis'' in North America: the great unknown|journal=Parasite|volume=21|year=2014|pages=73|issn=1776-1042|doi=10.1051/parasite/2014069|pmid=25531581|pmc=4273702|url=}}</ref> However, its distribution was not always like this.<ref name="dpd">{{ cite web | author = CDC | title = Parasites and Health: Echinococcosis | publisher = CDC | year = 2010 | url = http://www.dpd.cdc.gov/DPDx/html/Echinococcosis.htm | url-status = live | archive-url = https://web.archive.org/web/20100304104002/http://www.dpd.cdc.gov/dpdx/HTML/Echinococcosis.htm | archive-date = 4 March 2010 | df = dmy-all }}</ref> For instance, until the end of the 1980s, ''E. multilocularis'' endemic areas in Europe were known to exist only in France, Switzerland, Germany, and Austria. But during the 1990s and early 2000s, there was a shift in the distribution of ''E. multilocularis'' as the infection rate of foxes escalated in certain parts of France and Germany.{{cn|date=May 2021}}

As a result, several new endemic areas were found in Switzerland, Germany, and Austria and surrounding countries such as the Netherlands, Belgium, Luxembourg, Poland, the Czech Republic, the Slovak Republic, and Italy. There is also evidence showing that the Baltic Countries are endemic areas.<ref name=lassen>{{cite journal | last1 = Lassen| first1 = B. | last2 = Janson| first2 = M. | last3 = Viltrop| first3 = A. | last4 = Neare | first4 = K. | last5 = Hütt | first5 = P. | last6 = Golovljova | first6 = I. | last7 = Tummeleht | first7 = L. | last8 = Jokelainen| first8 = P. | year = 2016 | title = Serological Evidence of Exposure to Globally Relevant Zoonotic Parasites in the Estonian Population | doi =  10.1371/journal.pone.0164142 | journal = PLOS ONE | volume = 11 | issue = 10 | pages =e0164142   | pmid = 27723790 | pmc = 5056716 | bibcode = 2016PLoSO..1164142L }}</ref><ref name="Marcinkutė" >{{cite journal | last1 = Marcinkutė | first1 = A. | last2 = Moks | first2 = E. | last3 = Saarma | first3 = U. | last4 = Jokelainen | first4 = P. | last5 = Bagrade | first5 = G. | last6 = Laivacuma | first6 = S. | last7 = Strupas | first7 = K. | last8 = Sokolovas | first8 = V. | last9 = Deplazes | first9 = P. | year = 2015 | title = Echinococcus infections in the Baltic region | doi =  10.1016/j.vetpar.2015.07.032 | journal = Vet Par | volume = 213| issue = 3–4 | pages =121–31   | pmid = 26324242| doi-access = free }}</ref>

While alveolar echinococcosis is not extremely common, it is believed that in the coming years it will be an emerging or re-emerging disease in certain countries as a result of ''E. multilocularis''’ ability to spread.<ref name="Sréter03">{{cite journal |vauthors=Sréter T, Széll Z, Egyed Z, Varga I | title = ''Echinococcus multilocularis'': an Emerging Pathogen in Hungary and Central Eastern Europe | journal = Emerging Infectious Diseases | year = 2003 | volume = 9 | issue = 3 | pages = 384–6 | pmid = 12643838 | pmc = 2958538 | doi=10.3201/eid0903.020320}}</ref>{{update after|2015|7|8}}

Unlike the previous two species of ''Echinococcus'', ''E. vogeli'' and ''E. oligarthrus'' are limited to Central and South America. Furthermore, infections by ''E. vogeli'' and ''E. oligarthrus'' (polycystic echinococcosis) are considered to be the rarest form of echinococcosis.<ref name="JohnDavid">{{cite book |first1=David T. |last1=John |first2=William A. |last2=William Petri |first3=Edward K. |last3=Markell |first4=Marietta |last4=Voge |title=Markell and Voge's Medical Parasitology |chapter-url=https://books.google.com/books?id=-QSZD783cdsC&pg=PA224 |date=January 2006 |publisher=Elsevier Health Sciences |isbn=978-0-7216-4793-7 |pages=224–231 |edition=9th |chapter=7: The Cestodes: ''Echinococcus granulosus'', ''E. multiloularis'' and ''E. vogeli'' (Hyatid Disease) |url-status=live |archive-url=https://web.archive.org/web/20170908220823/https://books.google.com/books?id=-QSZD783cdsC&pg=PA224 |archive-date=8 September 2017  }}</ref>

=== Deaths ===
As of 2010 it caused about 1200 deaths, down from 2000 in 1990.<ref name="Loz2012" />

==Largest discovery==
The largest hydatid cyst discovered contained 37 litres of fluid and was removed from an 80-year-old at the King Fahd Central Hospital in [[Jizan]], [[Saudi Arabia]], on 12 January 2005. The main cyst had multiple daughter cysts attached and was found in his [[abdomen]].<ref>{{Cite web |url         = http://www.guinnessworldrecords.com/world-records/largest-hydatid-cyst |title       = Largest hydatid cyst |website     = Guinness World Records |access-date = 25 February 2016 |url-status     = live |archive-url  = https://web.archive.org/web/20160305231321/http://www.guinnessworldrecords.com/world-records/largest-hydatid-cyst |archive-date = 5 March 2016 |df          = dmy-all}}</ref>

==History==
[[File:Parasite130094-fig2 Cysts and laminated layer.tif|thumb|Laminated layer of a cyst found in a corpse in a grave from the late Roman period in France, interpreted<ref name=Mowlavi>{{Cite journal |last1=Mowlavi |first1=G. |last2=Kacki |first2=S. |last3=Dupouy-Camet |first3=J. |last4=Mobedi |first4=I. |last5=Makki |first5=M. |last6=Harandi |first6=MF. |last7=Naddaf |first7=SR. |title=Probable hepatic capillariosis and hydatidosis in an adolescent from the late Roman period buried in Amiens (France) |journal=Parasite |volume=21 |at=Article no. 9 |year=2014 |doi=10.1051/parasite/2014010 |pmid=24572211 |pmc=3936287 }}</ref> as a probable hydatidosis cyst]]

Echinococcosis is a disease that has been recognized by humans for centuries. There has been mention of it in the [[Talmud]]. It was also recognized by ancient scholars such as [[Hippocrates]], [[Aretaeus]], [[Galen]] and [[Rhazes]]. Although echinococcosis has been well known for the past two thousand years, it was not until the past couple of hundred years that real progress was made in determining and describing its parasitic origin. The first step towards figuring out the cause of echinococcosis occurred during the 17th century when [[Francesco Redi]] illustrated that the hydatid cysts of echinococcosis were of "animal" origin. Then, in 1766, [[Pierre Simon Pallas]] predicted that these hydatid cysts found in infected humans were actually larval stages of tapeworms.{{cn|date=May 2021}}

A few decades afterwards, in 1782, [[Johann August Ephraim Goeze|Goeze]] accurately described the cysts and the tapeworm heads, while in 1786 ''E. granulosus'' was accurately described by [[August Batsch|Batsch]]. Half a century later, during the 1850s, [[Karl Theodor Ernst von Siebold|Karl von Siebold]] showed through a series of experiments that ''Echinococcus'' cysts do cause adult tapeworms in dogs. Shortly after this, in 1863, ''E. multilocularis'' was identified by [[Rudolf Leuckart]]. Then, during the early to mid 1900s, the more distinct features of ''E. granulosus'' and ''E. multilocularis'', their life cycles and how they cause disease were more fully described as more and more people began researching and performing experiments and studies. While ''E. granulosus'' and ''E. multilocularis'' were both linked to human echinococcosis before or shortly after the 20th century, it was not until the mid 1900s that ''E. oligarthrus'' and ''E. vogeli'' were identified as and shown as being causes of human echinococcosis.<ref name="TappeDennis">{{cite journal |vauthors=Tappe D, Stich A, Frosch M |title=Emergence of polycystic neotropical echinococcosis |journal=Emerging Infect. Dis. |volume=14 |issue=2 |pages=292–7 |date=February 2008 |pmid=18258123 |pmc=2600197 |doi=10.3201/eid1402.070742 }}</ref><ref>{{cite journal |author=Howorth MB |title=Echinococcosis Of Bone |journal=J Bone Joint Surg Am |volume=27 |issue=3 |pages=401–411 |date=July 1945 |url=http://jbjs.org/content/27/3/401 |url-status=live |archive-url=https://web.archive.org/web/20160924162716/http://jbjs.org/content/27/3/401 |archive-date=24 September 2016  }}</ref><ref>{{cite web |last=Connolly |first=Stephanie |title=Echinococcosis |date=2006 |url=http://www.stanford.edu/group/parasites/ParaSites2006/Echinococcus/index.html |url-status=live |archive-url=https://web.archive.org/web/20081210161319/http://www.stanford.edu/group/parasites/ParaSites2006/Echinococcus/index.html |archive-date=10 December 2008  }}</ref>

Two calcified objects recovered from a 3rd- to 4th-century grave of an adolescent in Amiens (Northern France) were interpreted as probable hydatid cysts.<ref name=Mowlavi/> A study of remains from two 8,000-year-old cemeteries in Siberia showed presence of echinococcosis.<ref>Viegas, Jennifer [http://news.discovery.com/animals/dogs-and-women-140718.htm "Dogs Were a Prehistoric Woman's Best Friend, Too"] {{webarchive|url=https://web.archive.org/web/20141218104345/http://news.discovery.com/animals/dogs-and-women-140718.htm |date=18 December 2014 }} ''[[Discovery Communications]]'', 17 July 2014. Retrieved on 25 November 2014.</ref>
{{Clear}}

==References==
{{Reflist}}

==Further reading==
* {{Cite book|author1=Alimuddin I. Zumla|author-link=Alimuddin Zumla|author2=Gordon C. Cook|author3=Patrick Manson|title=Manson's tropical diseases |publisher=Saunders |location=Philadelphia |year=2003 |chapter=Section 10: Helminthic Infections 83. Echinococcosis/Hydatidosis |isbn=978-0-7020-2640-9 }}
* {{cite journal |vauthors=Vuitton DA, Millon L, Gottstein B, Giraudoux P |title=Proceedings of the international symposium — innovation for the management of echinococcosis. Besançon, March 27–29, 2014 |journal=Parasite |volume=21 |page=28 |year=2014 |doi=10.1051/parasite/2014024 |pmc=4071351 }}{{open access}}

==External links==
{{offline|med}}
* [https://www.who.int/neglected_diseases/diseases/echinococcosis/en/ WHO Echinococcosis Page]
* [https://www.cdc.gov/dpdx/echinococcosis/index.html CDC Echinococcosis Page]
* [http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/A-F/Echinococcosis/body_Echinococcosis_il1.htm Images of Echinococcus at CDC]
* [http://www.oie.int/fileadmin/Home/eng/Media_Center/docs/pdf/Disease_cards/ECHI-EN.pdf Disease card from World Organisation for Animal Health (OIE)]
{{Medical condition classification and resources|
  ICD10          = {{ICD10|B|67||b|65}} |
  ICD9           = {{ICD9|122.4}}, {{ICD9|122}} |
  ICDO           = |
  OMIM           = |
  DiseasesDB     = 4048 |
  MedlinePlus    = |
  eMedicineSubj  = med |
  eMedicineTopic = 629 |
  eMedicine_mult = {{eMedicine2|med|1046}} |
  MeshID         = D004443
}}
{{Helminthiases}}
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