hydatid disease

WordNet

1. an impairment of health or a condition of abnormal functioning
2. cyst filled with liquid; forms as a result of infestation by tapeworm larvae (as in echinococcosis)
3. caused by or altered by or manifesting disease or pathology; "diseased tonsils"; "a morbid growth"; "pathologic tissue"; "pathological bodily processes" (同)morbid, pathologic, pathological

PrepTutorEJDIC

1. (体の)『病気』,疾患 / (精神・道徳などの)病気,病弊
2. 女性の話術芸人 =diseur
3. 病気にかかった / 病的な,不健全な(morbid)

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/08/26 13:33:33」(JST)

wiki en

[Wiki en表示]

Echinococcosis
Classification and external resources
Echinococcus life cycle (click to enlarge)
ICD-10	B67
ICD-9	122.4, 122
DiseasesDB	4048
eMedicine	med/629 med/1046
MeSH	D004443

Echinococcosis, also called hydatid disease, hydatidosis, or echinococcal disease, is a parasitic disease of tapeworms of the Echinococcus type. People get two main types of disease, cystic echinococcosis and alveolar echinococcosis. There are two less common forms polycystic echinococcosis and unicystic echinococcosis. The disease often starts without symptoms and this may last for a year. The symptoms and signs that occur depend on the cyst's location and size. Alveolar disease usually begins in the liver but can spread to other parts of the body such as the lungs or brain. When the liver is affected the person may have abdominal pain, weight loss, and turn yellow. Lung disease may cause pain in the chest, shortness of breath and coughing.

The disease is spread when food or water that contains the eggs of the parasite is eaten or by close contact with an infected animal. The eggs are released in the stool of meat eating animals that are infected by the parasite. Commonly infected animals include: dogs, foxes and wolves. For these animals to become infected they must eat the organs of an animal that contains the cysts such as sheep or rodents. The type of disease which occurs in people depends on the type of Echinococcus causing the infection. Diagnosis is usually by ultrasound though computer tomography (CT) or magnetic resonance imaging (MRI) may also be used. Blood tests looking for antibodies against the parasite may be helpful as may biopsy.

Prevention of cystic disease is by treating dogs that may carry the disease and vaccination of sheep. Treatment is often difficult. The cystic disease may be drained through the skin followed by medication. Sometimes this type of disease is just watched. The alveolar type often needs surgery followed by medications. The medication used is albendazole which may be needed for years. The alveolar disease may result in death.

The disease occurs in most areas of the world and currently affects about one million people. In some areas of South America, Africa, and Asia up to 10% of the certain populations are affected. In 2010, it caused about 1200 deaths down from 2000 in 1990. The economic cost of the disease is estimated to be around 3 billion USD a year. It can affect other animals such as pigs, cows and horses.

Classification

The most common form found in humans is cystic echinococcosis (also known as unilocular echinococcosis), which is caused by Echinococcus granulosus. The second most common form is 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 not only has a significantly high fatality rate but also has the potential to become an emerging disease in many countries.

Signs and symptoms

Appearance of a typical cyst at removal

Cysts in a cotton rat

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 the patients 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 patients that are infected with alveolar and polycystic echinococcosis. 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.

Depending on the location of the cyst in the body, the patient 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 patient is symptomatic, the symptoms will depend largely on where the cysts are located. For instance, if the patient has cysts in the lungs and is symptomatic, they will have a cough, shortness of breath and/or pain in the chest. On the other hand, if the patient 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 some kind of trauma to the body, the patient 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.

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.

The incubation period for all species of Echinococcus can be months to years or even decades. It largely depends on the location of the cyst in the body and how fast the cyst is growing.

Cause

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 function as accidental hosts, because they are usually a 'dead end' for the parasitic infection cycle.

Hosts

Organism	Definitive Hosts	Intermediate Hosts
E. granulosus	dogs and other canidae	sheep, goats, 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	small rodents

Life cycle

An adult worm resides in the small intestine of a definitive host. Afterwards, gravid proglottids release 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 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

Eggs

Echinococcus Egg in Feces

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.

Larval/hydatid cyst stage

From the embryo released from an egg develops a hydatid cyst, which grows to about 5–10 cm within the first year and is able to survive within organs for years. 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 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 will also form within cysts.

Adult worm

Echinococcus adult worms develop from protoscolices and are typically 6mm 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). The scolex of the adult worm contains four suckers and a rostellum that has about 25–50 hooks.

Morphological differences

The major morphological difference among different species of Echinococcus is the length of the tapeworm. E. granulosus is approximately 2 to 7 mm while E. multilocuralis is often smaller and is 4 mm or less. On the other hand, E. vogeli is found to be up to 5.6 mm long and E. oligarthrus is found to be up to 2.9 mm long. 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.

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.

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.

Diagnosis

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.

Cystic

In order to formally diagnose a patient with any type of echinococcosis, one must use a combination of tools that involve imaging techniques, histopathology and/or nucleic acid detection and serology. For cystic echinococcosis, imaging is the main method that is relied on for diagnosis while serology tests (such as indirect hemogglutination, ELISA (enzyme linked immunosorbent assay), immunoblots or latex agglutination) that use antigens specific for E. granulosus are used to 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 but it is also inexpensive, non-invasive and gives instant results. 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.

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. In addition to imaging and serology, identification of E. multilocularis infection via PCR or a histological examination of a tissue biopsy from the patient is another way to diagnose alveolar echinococcosis.

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 patient’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 patient’s death and the identification of definitive features of E. oligarthrus and E. vogeli in these isolated protoscoleces. Although this is the main way in which PE is diagnosed, there are current studies that have shown that PCR may be used to identify E. oligarthrus and E. vogeli in patients’ tissues. 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.

Prevention

Cystic echinococcosis

There are several different strategies that are currently being used to prevent and control cystic echinococcosis. Most of these various methods try to prevent and control cystic echinococcosis 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 (i.e. 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.

Alveolar echinococcosis

There are also a number of strategies geared towards the prevention and control of alveolar echinococcosis, most of which are similar to those of cystic echinococcosis. For instance, health education programs, improved water sanitation, improved hygiene and de-worming of hosts, in particular, red foxes, are all ways in which a country can prevent and control the spread of alveolar echinococcosis. Unlike cystic echinococcosis, though, where there is a vaccine against E. granulosus, there is currently no canidae or livestock vaccine against E. multilocularis.

Polycystic echinococcosis

While there are a number of control and prevention strategies dealing with cystic and alveolar echinococcosis, there aren’t many methods specified for the control and prevention of polycystic echinococcosis. This is probably due to the fact that polycystic echinococcosis is restricted to only Central and South America and that the way in which humans become accidental hosts of E. oligarthrus and E. vogeli is still not completely understood.

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.

Treatment

Cystic

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. In the case of alternative treatment using just chemotherapy, albendazole is preferred twice a day for 1–5 months. 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. Patients who undergo PAIR typically take albendazole or mebendazole from 7 days before the procedure until 28 days after the procedure. 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. 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. An alternative to open surgery is laparoscopic surgery, which provides excellent cure rates with minimal morbidity and mortality.

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. 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 the patient of disease, patients 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 patient afterwards.

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.

Epidemiology

Location of patients, controls, and areas in France where persons are at risk for alveolar echinococcosis. See legend below the image.

Very few countries are considered to be completely free of E. granulosus. As of 2010 it caused about 1200 death down from 2000 in 1990. 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.

E. multilocularis mainly occurs in the Northern hemisphere, including central Europe and the northern parts of Europe, Asia, and North America. However, its distribution was not always like this. 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. 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. 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.

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.

History

Laminated layer of a cyst found in a corpse in a grave from the late Roman period in France, interpreted 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 wasn’t 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. A few decades afterwards, in 1782, Goeze accurately described the cysts and the tapeworm heads while in 1786, E. granulosus was accurately described by Batsch. Half a century later, during the 1850s, 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 wasn’t until the mid 1900s that E. oligarthrus and E. vogeli were identified as and shown as being causes of human echinococcosis.

Two calcified objects recovered from a 3rd to 4th-century grave of an adolescent in Amiens (Northern France) were interprated as probable hydatid cysts.

References

Further reading

• Alimuddin I. Zumla; Gordon C. Cook; Patrick Manson (2003). "Section 10: Helminthic Infections 83. Echinococcosis/Hydatidosis". Manson's tropical diseases. Philadelphia: Saunders. ISBN 0-7020-2640-9. 
• Vuitton DA, Millon L, Gottstein B, Giraudoux P (2014). "Proceedings of the international symposium — innovation for the management of echinococcosis. Besançon, March 27–29, 2014". Parasite 21 (28). doi:10.1051/parasite/2014024. PMID 24960689. 

External links

• WHO Echinococcosis Page
• CDC Echinococcosis Page
• Images of Echinococcus at CDC
• Removal by brain surgery

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

• 1. エキノコックス症の臨床症状および診断 clinical manifestations and diagnosis of echinococcosis
• 2. エキノコックス症の治療および予防 treatment of echinococcosis
• 3. エキノコックス症の疫学および制御 epidemiology and control of echinococcosis
• 4. Diseases potentially acquired by travel to Southern Africa
• 5. Diseases potentially acquired by travel to East Africa

English Journal

• Feasibility study of high intensity focused ultrasound (HIFU) for the treatment of hydatid cysts of the liver.

• Imankulov SB1, Fedotovskikh GV2, Shaimardanova GM2, Yerlan M2, Zhampeisov NK2.
• Ultrasonics sonochemistry.Ultrason Sonochem.2015 Nov;27:712-6. doi: 10.1016/j.ultsonch.2015.05.025. Epub 2015 May 27.
• This study evaluates the feasibility of using high intensity focused ultrasound (HIFU) for the treatment of hydatid cysts of the liver. HIFU ablation was carried out in 62 patients with echinococcosis of the liver. The mean age of patients was 40.76±14.84 (range: 17-72years). The effectiveness of t
• PMID 26050602

• Chemoprophylactic and therapeutic efficacy of thymol in murine cystic echinococcosis.

• Maggiore M1, Pensel PE2, Denegri G2, Elissondo MC3.
• Parasitology international.Parasitol Int.2015 Oct;64(5):435-40. doi: 10.1016/j.parint.2015.06.005. Epub 2015 Jun 19.
• Cystic echinococcosis is a zoonotic disease caused by the larval stage of the cestode Echinococcus granulosus. The drugs commonly used against cystic echinococcosis are benzimidazoles. Unfortunately, 20%-40% of cases do not respond favorably to such chemotherapy. Consequently, the search of new ther
• PMID 26096310

• The first report of human-derived G10 genotype of Echinococcus canadensis in China and possible sources and routes of transmission.

• Yang D1, Zhang T2, Zeng Z3, Zhao W1, Zhang W4, Liu A5.
• Parasitology international.Parasitol Int.2015 Oct;64(5):330-3. doi: 10.1016/j.parint.2015.05.001. Epub 2015 May 9.
• Cystic echinococcosis (CE) is one of the most important parasitic zoonoses. 10 distinct genotypes, designated G1-G10 genotypes of Echinococcus granulosus sensu lato (s.l.), have been split into 4 species: Echinococcus granulosus sensu stricto (s.s.) (G1-G3), Echinococcus equinus (G4), Echinococcus o
• PMID 25967082

Japanese Journal

• Cystic Hydatidosis of the Rib–Case Report and Review of the Literature

• Annals of Thoracic and Cardiovascular Surgery 21(5), 492-495, 2015
• NAID 130005104678

• Cystic Hydatidosis of the Rib–Case Report and Review of the Literature

• Annals of Thoracic and Cardiovascular Surgery advpub(0), 2015
• NAID 130005072779

• 福岡県のと畜場に搬入された馬にみられた肝臓灰白色硬結節と多包虫感染との関連性

• 日本獣医師会雑誌 68(4), 253-257, 2015
• NAID 130005071180

Related Links

• 包虫症 (hydatid disease, echinococcosis) とは - コトバンク

馬の用語事典 包虫症 (hydatid disease, echinococcosis)の用語解説 - 包虫(単包虫および多包虫)の寄生によって発生する嚢腫を指す。成虫は犬、狐などの小腸内に寄生しているが、幼虫は人を含め各種動物に寄生し、馬でも肝臓などに包虫と ...

• Alveolar hydatid disease (エキノコックス症)の診断

Alveolar hydatid disease (エキノコックス症)の診断 伊藤 智雄 北海道大学病院病理部 主なエキノコックスには多包条虫Echinococcus multilocularisと単包条虫Echinoccus granulosusの2種類が知られ、北海道のヒトでみられるものは前者の ...

Related Pictures

---

★リンクテーブル★

リンク元	「包虫症」「hydatidosis」
関連記事	「disease」「hydatid」

「包虫症」

　　[★]

英

hydatid disease

同

エキノコックス症(四類感染症) echinococcosis

関

包虫症、多包虫症、包虫嚢胞、肝包虫症

• エキノコックス属の感染によって起こる疾患

種類

• 単包条虫　Echinococcus granulosus 単包虫症　世界的分布(牧畜)
• 多包条虫　Echinococcus multilocularis 多包虫症　日本では北海道全域

宿主

• 終宿主:イヌ､キツネなど
• 中間宿主:ヒト､ブタ､野ネズミなど

• 終宿主の糞便中の虫卵を中間宿主が摂取して発症

包虫形成部位

• 肝､肺､まれに脳､腎､筋肉

• 肝臓：小腸で孵化した幼虫が門脈より肝臓に運ばれ胞虫を形成する。肝病変に次いで肺病変が多い。無症状の長い潜伏期を経て肝腫、門脈亢進をきたす。

症状

• 肝寄生　肝部落痛､腹満､時に黄症､下肢浮腫
• 肺寄生　胸部圧迫感､胸痛､咳､血痕､時に噂血

診断

• 肝や肺の嚢胞形成から疑う
• 早期診断に皮内反応､免疫血清学的診断法

治療

• 外科的切除
• アルベンダゾール(albendazole)の長期投与

「hydatidosis」

　　[★]

包虫症

関

echinococcosis、hydatid cyst、hydatid disease

「disease」

　　[★]

• n.

疾患：illnessより厳密な概念。「ある臓器に明確な障害が確認され、それによって症状が出ているとはっきり説明できる場合」 (PSY.9)

特定の原因、病態生理、症状、経過、予後、病理組織所見が全てそろった場合 (PSY.9)

• something that is very wrong with people's attitudes, way of life or with society.

関

ail、ailment、disease entity、disorder、ill、illness、malady、sick、sickness

• 注意

disease ≠ illness ≠ disorder

　 　 　

「hydatid」

　　[★]

hydat

• n.

• (病理)小嚢胞、胞虫嚢(条虫 Echinococcus granulosusの幼虫が人または動物の体内に作る嚢胞)
• (医学)水胞体(胎児期の特徴が見られる嚢胞痕跡)
• 条虫の幼虫、胞虫

• adj.