Hydatid disease

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Hydatid disease

Hydatid disease

Hydatid disease also called hydatidosis, cystic echinococcosis or cystic hydatidosis, is a parasitic tapeworm disease caused by the ingestion of Echinococcus tapeworm eggs in contaminated food, water or soil, or after direct contact with animal hosts, leading to the formation of larval cysts, primarily in your liver and lungs, that can cause symptoms after years ¹, ², ³, ⁴, ⁵, ⁶, ⁷, ⁸, ⁹, ¹⁰, ¹¹, ¹². Echinococcosis is a zoonosis, a disease that is transmitted to humans from animals. Normally, Echinococcus granulosus completes its life cycle involving dogs (definitive host) and sheep and goats (intermediate hosts) (see Hydatid disease Life Cycle below) ¹³. There are two hosts in the life-cycle of the Echinococcus granulosus tapeworm. The first one is the “primary host” or “definitive host” and the second one is the “intermediate host” in which the illness occurs (see Hydatid disease Life Cycle below). Adult Echinococcus granulosus tapeworms are present in the intestines of primary hosts (definitive hosts) including cats, dogs, wolfs and foxes, and they only cause intestinal parasitosis but not organ disease. Adult Echinococcus granulosus tapeworm lives approximately for 5 months in dog intestines ¹⁴, ¹⁵. “Definitive hosts” spread millions of Echinococcus granulosus eggs on defecation. Sheep and other herbivorous animals (goats, swine, camels, horses, cattle, mule deer) becomes “intermediate host” for Echinococcus granulosus tapeworm when they eat herbs contaminated with these eggs, or humans become “intermediate host” for the Echinococcus granulosus tapeworm when they eat food contaminated with these eggs ¹⁶. Embryo (oncosphere) which comes out of the egg taken via gastrointestinal tract, adheres to intestinal wall with its hooks, then enters into circulation and reaches firstly to the liver. Therefore, liver is the most common site of disease in humans accounting for 50–70% of cases, followed by the lungs (20–30%), and less frequently the spleen, kidneys, heart, bones, central nervous system (brain and spinal cord), and other organs ¹⁵. The Echinococcus granulosus tapeworm embryo loses its scolex (head) when it settles in an organ, and takes the cyst form consisting of cuticula (exocyst) and germinal membrane (endocyst). The cyst, which are slow growing fluid-filled structures that contain the larvae, has sterile, clear fluid inside, and this cystic structure is wrapped with a fibrous capsule “pericyst”. When alive hydatid cysts are eaten by the last host dog, the infection chain is completed, and the life cycle returns to beginning ¹⁷, ¹⁸.

According to the World Health Organization (WHO), Echinococcus granulosus tapeworm is endemic in South America, Eastern Europe, Russia, the Middle East, and China, where human incidence rates are as high as 50 per 100,000 person-years ¹⁹. In certain areas, such as slaughter houses in South America, prevalence varies from 20% to as high as 95% ¹⁹. The most common intermediate hosts are farm animals, such as sheep, goats, swine, camels, horses, and cattle, as well as mule deer ¹⁶. The incidence of surgical cases reflects only a fraction of the number of infected hosts, which, in turn, is only a fraction of the actual prevalence in endemic areas. Foci of hydatid disease also exist in India where the highest prevalence is reported in Andhra Pradesh and Tamil Nadu than in other parts of the country ²⁰, ²¹. Tanzania, Malta, South Cyprus and New Zealand became hydatid cyst free zones with their applied public health policies ²². Factors such as agriculture-based subsistence, low socio-economic status, regional climate, and uncontrolled and unhygienic animal slaughtering increase the incidence.

Human serves as a intermediate dead-end host and is affected by hydatidosis. This can happen only when human consumes foods or water contaminated by the feces of infected stray dogs ¹³. Most Echinococcus granulosus tapeworm cysts are acquired in childhood and are not diagnosed until the third or fourth decade of life; only about 10 to 25% of cases present in childhood ²³. Hydatid cysts (which are slow growing fluid-filled structures that contain the larvae) may develop anywhere from your toe to the top of your head, but are commonly located in your liver and less commonly your heart, eyes, brain, kidneys, and bones; pancreatic involvement is occasional and is estimated to range from 0.14 to 2% ²⁴, ¹³, ²⁵, ²⁶, ²⁷, ²⁸.

People with hydatid disease or cystic echinococcosis (Echinococcus granulosus) often remain asymptomatic for 10 years or more until the hydatid cysts containing the larval parasites, located most often in the liver and lungs, and less frequently in the bones, kidneys, spleen, muscles and central nervous system including the brain and eyes, grow large enough to cause discomfort, pain, nausea, and vomiting. Abdominal pain, nausea and vomiting are commonly seen when hydatids occur in the liver. If the lung is affected, clinical signs include chronic cough, chest pain and shortness of breath. Other signs depend on the location of the hydatid cysts and the pressure exerted on the surrounding tissues. Non-specific signs include anorexia, weight loss and weakness.

As hydatid disease (Echinococcus granulosus) advances and the cysts get larger, symptoms may include:

Pain in the upper right part of the abdomen (liver cyst)
Increase in size of the abdomen due to swelling (liver cyst)
Bloody sputum (lung cyst)
Chest pain (lung cyst)
Cough (lung cyst)
Severe allergic reaction (anaphylaxis) when cysts break open

Rupture of the cysts can produce a host reaction manifesting as fever, urticaria, eosinophilia, and potentially anaphylactic reactions, even death as a result of the release of cystic fluid. Rupture of the cyst may also lead to cyst dissemination.

Ultrasound imaging is the technique of choice for the diagnosis of cystic echinococcosis in humans ²⁹. Ultrasound imaging technique is usually complemented or validated by computed tomography (CT) and/or magnetic resonance imaging (MRI) scans. Echinococcus cysts can also be incidentally discovered by x-ray.

Specific antibodies are detected by different serological tests and can support the diagnosis. Indirect hemagglutination (IHA), indirect fluorescent antibody (IFA) tests, and enzyme immunoassays (EIA) are sensitive tests for detecting antibodies in serum of patients with hydatid disease (Echinococcus granulosus); sensitivity rates vary from 60% to 90%, depending on the characteristics of the cases and antigens used. At present, the best available serologic diagnosis is obtained by using combinations of tests. Enzyme immunoassays (EIA) or indirect hemagglutination (IHA) can be used for screening; positive reactions should be confirmed by immunoblot assay. As some tests may cross-react with sera from persons with cysticercosis, clinical and epidemiological information should also be used to support diagnosis. A commercial enzyme immunoassays (EIA) kit is available in the United States.

In seronegative patients with liver image findings compatible with echinococcosis, ultrasound guided fine needle biopsy may be useful for confirmation of diagnosis ²⁹. During a ultrasound guided fine needle biopsy procedure, precautions must be taken to control allergic reactions or prevent secondary recurrence in the event of leakage of hydatid fluid or protoscolices.

Hydatid disease treatment options in humans include: (i) anti-parasitic drug treatment (albendazole or mebendazole); (ii) cyst puncture, and PAIR (Puncture, Aspiration, Injection, Re-aspiration) technique, standard catheterization or the modified catheterization technique; (iii) surgery; and (iv) the “watch and wait” approach.

In the past, surgery was the only treatment for cystic echinococcal (Echinococcus granulosus) cysts. Antiparasitic drugs (albendazole or mebendazole), cyst puncture, and PAIR (percutaneous aspiration, injection of chemicals and reaspiration) have been used to replace surgery as effective treatments for cystic echinococcosis (Echinococcus granulosus) and, for some cases, no treatment but a conservative “watch and wait” approach is best. Treatment indications vary with cyst characteristics, including cyst type, location, size, and complications. Surgery may be the best treatment for liver cysts that are secondarily infected, or cysts located in the brain, lungs, or kidney. Liver cysts larger than 7.5 cm are likely to have biliary communication; surgery may be the best option for these cysts. Many abdominal cysts can be treated by injection of protoscolicidal chemical solutions into the cyst, followed by evacuation, prior to further manipulations and extirpation of cysts.

For some patients, drug treatment with benzimidazoles is the preferred treatment. Approximately one third of patients treated with benzimidazole drugs have been cured of cystic echinococcosis (Echinococcus granulosus) and even higher proportions, between 30 – 50%, have responded with significant regression of the cyst size and alleviation of symptoms.

Patients with small cysts or multiple cysts in several organs can be treated successfully with albendazole.

Both albendazole 10 – 15 mg/kg body weight per day (max 800 mg orally in two doses) and, as a second choice for treatment, mebendazole 40 – 50 mg/kg body weight per day continuously for several months have been highly effective. Additionally, antiparasitic drugs can be very effective when used in conjunction with surgery. Albendazole has been administered to patients prior to surgery for the intended purpose of facilitating the safe surgical manipulation of the cysts by inactivating protoscolices, altering the integrity of the cyst’s membranes, and reducing the turgidity of the cysts.

Praziquantel may be useful preoperatively or in case of spillage of cyst contents during surgery ³⁰.

A third treatment option, PAIR (percutaneous aspiration, injection of chemicals and reaspiration), has been shown to be effective. This option is indicated for patients with relapse after surgery, failure of antiparasitic drug alone, or who refuse surgery.

Figure 1. Hydatid disease adult tapeworm (Echinococcus granulosus adult worm)

Footnotes: As dogs and other canids (animals from the dog family) are the only definitive hosts for most Echinococcus tapeworms, adult Echinococcus worms are not expected to be found in the human host. Humans are only infected by the Echinococcus larvae after ingestion of eggs from food, water or fomites contaminated with dog feces. Upon ingestion of the Echinococcus eggs by the human host, the oncospheres migrate from the intestinal lumen to other body sites where they develop into hydatid cysts. These cysts can be found in any part of the body, but are most common in the liver, lung and central nervous system (see Echincoccoosis Life Cycle below). Adult Echinococcus tapeworms range from 1.2 to 9 mm in length (depending on Echinococcus species) and usually consist of a sucker (head) and usually no more than six proglottids (segments). The terminal proglottid is gravid segment containing the uetrus and is longer than wide. The scolex (head) contains four cuplike oval suckers and a rostellum with 25 to 50 hooks. Large numbers of adult Echinococcus tapeworms may be found in the small intestines of dogs which are infected by eating the remnants of sheep, cattle or other animals containing hydatid cysts. The uterus in the gravid unit can hold up to 500 eggs, which are released into the feces through the ruptured segment. The subspherical egg is 34 to 41 micrometer in diameter, with a brown hexacanth embryo, and resembles those of other Taenia worms in appearance. Upon ingestion of eggs by the human host, the oncospheres migrate from the intestinal lumen to other body sites via circulation and develop into hydatid cysts. These cysts can be found in any part of the body, but are most common in the liver, lung and central nervous system (see Echincoccoosis Life Cycle below).

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Figure 2. Echinococcus developmental stages

Footnotes: Different developmental stages in Echinococcus granulosus and Echinococcus multilocularis. Growth of the larval cyst is unlimited, and it can, for Echinococcus granulosus, grow to 30 cm or more in humans, while the adult worm, egg, and protoscolex are limited in size and shape. Echinococcus tapeworms have no gut, circulatory, or respiratory organs and have a highly adapted relationship with their mammalian hosts which they exploit for nutrients, signaling pathways, and neuroendocrine hormones. Strobilization is a notable feature of cestode biology, whereby proglottids (segments) bud distally from the anterior scolex, resulting in the production of tandem reproductive units (proglottids) exhibiting increasing degrees of development. Echinococcus is monoecious, and the last segment (gravid proglottid) produces diploid eggs that give rise to ovoid embryos, the oncospheres. However, a striking feature of the biology of Echinococcus is that the protoscolex has the potential to develop in either of two directions: it may develop into an adult tapeworm producing sexually produced eggs in the dog gut, or, if a hydatid cyst ruptures within the intermediate or human host, each released protoscolex is capable of differentiating asexually into a new cyst, a process termed “secondary echinococcosis”. While a unilocular fluid-filled bladder (cyst) is a feature of Echinococcus granulosus sensu lato in its larval stage, the metacestode of Echinococcus multilocularis consists of a mass of small, multilocular vesicles embedded in the immune reaction of the host (granuloma and fibrosis). These multiple and aggregated vesicles grow by proliferation of cells in the germinal layer of the metacestode.

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Figure 3. Liver hydatid cyst

Footnotes: The hydatid cyst is characteristically a round cystic lesion that consists of an inner nucleated layer of the cyst (germinal layer) referred to as the endocyst, and an outer acellular layer of the cyst (laminated layer) referred to as the ectocyst. The inner germinal layer produces small vesicles called brood capsules that divide via asexual division and produce many protoscolices. Around the echinococcal laminated layer lies a granulomatous, adventitial layer known as the pericyst. This granulomatous layer is produced by the host’s immune system to wall off the cystic infection and is often seen in imaging studies. The protoscolex, the future head of the adult worm, is seen here budding from the germinal layer, and the daughter cyst is seen here floating within the main cyst. The hydatid sand is a sonographic finding representing a combination of cystic fluid and protoscolices.

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Figure 4. Lung hydatid disease

Footnotes: (a) Uncomplicated pulmonary cystic echinococcosis. The radiograph shows pulmonary cystic echinococcosis dissemination with multiple well defined masses in both lungs. As there is no evidence of intralesional air, uncomplicated unruptured cystic echinococcosis can be suggested to be present. (b and c) Pulmonary cystic echinococcosis with mass effect on heart and great vessels. T2-weighted MRI (b) shows a large CE3b cyst consisting of solid matrix and daughter cysts in the right hemithorax (asterisk) with severe compression of the heart (arrow). Magnetic resonance angiography (c) depicts severe compression, especially of the distal superior vena cava. Clinically, there was superior vena cava syndrome.

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Figure 5. Lung and liver hydatid cyst

Footnotes: Cyst appearances on lung CT and abdominal CT in 2 different patients with positive Echinococcus Indirect hemagglutination (IHA).

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How are dogs, cattle, sheep, and other domestic animals infected with Echinococcus?

Dogs serve as the definitive host for Echinococcus granulosus (cystic echinococcosis), and wild canids (animals from the dog family) are the main definitive hosts for Echinococcus multilocularis (alveolar echinococcosis). The definitive hosts carry adult tapeworms in their intestines (which are very small, 1.5 to 7mm long) without showing symptoms. They shed parasite eggs in feces.

For cystic echinococcosis (Echinococcus granulosus), livestock like sheep, cattle, goats, and pigs act as intermediate hosts. For alveolar echinococcosis (Echinococcus multilocularis), rodents act as intermediate hosts. Intermediate hosts get infected by ingesting Echinococcus eggs shed by the definitive hosts, from contaminated environments, which form cysts in their organs—primarily the liver and lungs. Definitive hosts get infected by eating those cysts when for example contaminated livers are fed to dogs, or when foxes eat infected rodents.

The cysts in livestock rarely cause clinical illness in animals, but infected organs (offal) are unsafe for consumption at slaughter, resulting in economic losses.

Is echinococcosis contagious and can it be transmitted from humans to humans?

Echinococcosis is zoonotic parasitic infection (parasite disease that is transmitted to humans from animals) and is not contagious between humans. The Echinococcus tapeworms requires an animal host, and human-to-human transmission is rare, except in cases like organ transplantation or accidental cyst fluid exposure during surgery (see Echinococcus Life Cycle below).

What causes hydatid disease

Human hydatid disease is caused by accidental ingestion of Echinococcus granulosus sensu lato tapeworm eggs, shed in the feces of infected definitive hosts, primarily dogs for Echinococcus granulosus (cystic echinococcosis). The Echinococcus granulosus eggs can be present on contaminated animals’ fur, soil, food, water, or other surfaces (e.g., unwashed vegetables, untreated water).

Echinococcus granulosus (sensu lato) is the cause of hydatid disease or cystic echinococcosis and is the type most frequently encountered. Echinococcus granulosus has a worldwide distribution, and the highest prevalence is observed in pastoral communities. It is the most common cause of echinococcosis in humans in which typically forms slow-growing fluid-filled cysts in the liver or lungs, causing symptoms like abdominal pain or cough.

Mitochondrial DNA sequencing has identified 10 distinct genotypes of Echinococcus granulosus (G1 to G10) that differ in their distribution, host range, and some morphological features; these are often grouped into separate species in modern literature ³², ³³. The known zoonotic genotypes within the Echinococcus granulosus sensu lato complex include the “classical” Echinococcus granulosus sensu stricto (G1–G3 genotypes), Echinococcus ortleppi (G5), and the Echinococcus canadensis group (usually considered G6, G7, G8, and G10) ³⁴, ³⁵, ³⁶, ⁴, ³. These include two sheep strains (G1 and G2), two bovid strains (G3 and G5), a horse strain (G4), a camelid strain (G6), a pig strain (G7), and a cervid strain (G8). A ninth genotype (G9) has been described in swine in Poland and a tenth strain (G10) in reindeer in Eurasia ³⁶. The sheep strain (G1) is the worldwide form and is most commonly associated with human infections ³². Certain human activities (e.g. the widespread rural practice of feeding dogs the organs of home-butchered sheep) facilitate transmission of the sheep strain and consequently raise the risk that humans will become infected ³³.

There are two hosts in the life-cycle of the Echinococcus granulosus tapeworm. The first one is the “primary host” or “definitive host” and the second one is the “intermediate host” in which the illness occurs. Adult Echinococcus granulosus tapeworms are present in the intestines of primary hosts including cats, dogs, wolfs and foxes, and they only cause intestinal parasitosis but not organ disease. Adult Echinococcus granulosus tapeworm lives approximately for 5 months in dog intestines ¹⁴, ¹⁵. “Definitive hosts” spread millions of Echinococcus granulosus eggs on defecation. Sheep and other herbivorous animals becomes “intermediate host” for the parasite when they eat herbs contaminated with these eggs, or humans become “intermediate host” for the Echinococcus granulosus tapeworm when they eat food contaminated with these eggs. Embryo (oncosphere) which comes out of the egg taken via gastrointestinal tract, adheres to intestinal wall with its hooks, then enters into circulation and reaches firstly to the liver. Therefore, liver is the most common site of disease in humans accounting for 50–70% of cases, followed by the lungs (20–30%), and less frequently the spleen, kidneys, heart, bones, central nervous system, and other organs ¹⁵. The Echinococcus granulosus tapeworm embryo loses its scolex (head) when it settles in an organ, and takes the cyst form consisting of cuticula (exocyst) and germinal membrane (endocyst). The cyst has sterile, clear fluid inside, and this cystic structure is wrapped with a fibrous capsule “pericyst”. When alive hydatid cysts are eaten by the last host dog, the infection chain is completed, and the life cycle returns to beginning ¹⁷, ¹⁸.

Hydatid disease Life Cycle

The adult Echinococcus granulosus sensu lato (2mm to 7 mm long) resides in the small intestine of the definitive host (dogs, wolves, jackals, domestic cats, and reindeer etc) (number 1). Gravid proglottids (each proglottid contains hundreds of eggs) release eggs (number 2) that are passed in the feces, and are immediately infectious. After ingestion by a suitable intermediate host (sheep, cattle, pigs and humans), eggs hatch in the small intestine and release six-hooked oncospheres (number 3) that penetrate the intestinal wall and migrate through the circulatory system into various organs, especially the liver and lungs. In these organs, the oncosphere develops into a thick-walled hydatid cyst (number 4) that enlarges gradually, producing protoscolices and daughter cysts that fill the cyst interior. The definitive host becomes infected by ingesting the cyst-containing organs of the infected intermediate host. After ingestion, the protoscolices (number 5) evaginate, attach to the intestinal mucosa (number 6), and develop into adult stages (number 1) in 32 to 80 days.

Humans are accidental intermediate hosts, and become infected by direct contact with a dog contaminated with egg-bearing feces or by ingesting water, food, or soil contaminated with egg-bearing feces (number 2). In human infection, the first stage is the asymptomatic incubation period, during which the ingested Echinococcus granulosus sensu lato eggs release oncospheres that are able to penetrate the human intestinal wall (number 3). These oncospheres enter the portal venous system, which provides access to the liver, lungs, and various other organs ³⁷, ³⁸, ³⁹. Next, the oncospheres begin cyst development in a variety of organs (number 4). Cysts are usually unilocular, and can range anywhere from 1 cm to 15 cm in diameter. In hydatid disease, cyst growth ranges from 1–2 mm to 10 mm per year. They also tend to affect the right lobe of the liver more frequently than the left lobe of the liver due to the nature of portal blood flow. The cysts are composed of two layers of membrane: an inner, nucleated, germinal membrane, and an outer, acellular, laminated layer. The immune system responds to the cyst by forming a calcified fibrous capsule around it, which is the layer that is most often visualized on imaging studies ³⁶. The cyst enlarges to form a combination of protoscolices and daughter cysts. The combination of many protoscolices and cystic fluid appears grain-like on ultrasound imaging, and is termed “hydatid sand” ³⁶. If cysts rupture, the liberated protoscolices may create secondary cysts in other sites within the body (secondary echinococcosis). Animals that consume organs infected with protoscolices will become definitive hosts (number 5), as the protoscolices attach firmly to the host’s intestine (number 6), and then develop into an adult worm with a scolex (head), neck, and proglottids ⁴⁰. Echinococcus granulosus infections usually present as solitary cysts, and have single-organ involvement. In 10–15% of patients, there can be involvement of two organs depending on the specific geographic region and strain of parasite ³⁶.

Figure 6. Hydatid disease Life Cycle (Echinococcus granulosus sensu lato life cycle)

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Hydatid disease Geographic Distribution

Hydatid disease (Echinococcus granulosus sensu lato) occurs worldwide (except Antarctica) and more frequently in rural, grazing areas where dogs ingest organs from infected animals. The pattern of distribution for cystic echinococcosis has remained essentially unchanged over the past 2 decades, with areas of high endemicity, including western China, Central Asia, South America, Mediterranean countries and eastern Africa and the main risk factors being contact with dogs and raising livestock ⁴², ⁴³, ⁴⁴. However, studies in Africa have revealed a significant number of human cases and active transmission in animals, including wildlife, in countries up to now considered not to be areas of endemicity ⁴⁵, ⁴⁶. In endemic regions, human incidence rates for cystic echinococcosis (Echinococcus granulosus) can reach more than 50 per 100,000 person-years, and prevalence levels as high as 5% to 10% may occur in parts of Argentina, Peru, East Africa, Central Asia and China. Five thousand new cystic echinococcosis cases are still diagnosed annually in Argentina, Brazil, Chile, Peru, and Uruguay ⁴⁷, ⁴⁸. Thirty years of dosing dogs with the anthelmintic drug praziquantel 8 times annually has significantly decreased transmission to humans, but cystic echinococcosis is still present in a number of areas in South America ⁴⁷, ⁴⁹. In livestock, the prevalence of cystic echinococcosis (Echinococcus granulosus) found in slaughterhouses in hyperendemic areas of South America varies from 20% to 95% of slaughtered animals. The highest prevalence of cystic echinococcosis (Echinococcus granulosus) is found in rural areas where older animals are slaughtered. Depending on the infected species involved, livestock production losses attributable to cystic echinococcosis result from liver condemnation and may also involve reduction in carcass weight, decrease in hide value, decrease of milk production, and reduced fertility.

The geographic distribution of individual Echinococcus granulosus genotypes is variable and an area of ongoing research. The lack of accurate Echinococcus granulosus case reporting and genotyping currently prevents any precise mapping of the true epidemiologic picture. However, Echinococcus granulosus genotypes G1 and G3 (associated with sheep) are the most commonly reported at present and broadly distributed. In North America, Echinococcus granulosus is rarely reported in Canada and Alaska, and a few human cases have also been reported in Arizona and New Mexico in sheep-raising areas. In the United States, most infections are diagnosed in immigrants from counties where cystic echinococcosis (Echinococcus granulosus) is endemic. Some Echinococcus granulosus genotypes designated “Echinococcus canadensis” occur broadly across Eurasia, the Middle East, Africa, North and South America (G6, G7) while some others seem to have a northern holarctic distribution (G8, G10).

Hydatid disease has been declared eliminated from New Zealand, and Tasmania in Australia is considered to be provisionally free of the disease ⁵⁰; nevertheless, Echinococcus granulosus is present on the Australian mainland and is still found in Tasmanian wild and rural dogs, but at low prevalence ⁵¹. In Western Europe and North America, most human cases are imported, although an indigenous cycle of various genotypes within the species group E. granulosus sensu lato is present. However, the lack of accurate case recording currently prevents any precise mapping of the true epidemiological picture; a European Registry of cystic echinococcosis (the Heracles project) has been launched to improve this situation ⁵².

Hydatid disease Hosts

Hydatid disease (Echinococcus granulosus) definitive hosts are wild and domestic canids (animals from the dog family). Natural intermediate hosts depend on genotype. Intermediate hosts for zoonotic species/genotypes are usually ungulates, including sheep and goats (Echinococcus granulosus sensu stricto), cattle (“Echinococcus ortleppi”/G5), camels (“Echinococcus canadensis”/G6), and cervids (“Echinococcus canadensis”/G8, G10).

Hydatid disease prevention

The main tools for prevention of hydatid disease or cystic echinococcosis (Echinococcus granulosus) transmission are the regular deworming of dogs with praziquantel (at least 4 times per year) and vaccination of sheep with the EG95 vaccine ⁵³. Recent trials in Australia and Argentina using EG95 recombinant vaccine have reported that 86% of vaccinated sheep were completely free of viable hydatid cysts when examined 1 year after immunization. Vaccination reduced the number of viable cysts by 99.3% ⁵⁴. A vaccine has also been developed against the dog tapeworm stage, which conferred 97–100% protection against worm growth and egg production ⁵⁵.

Strategies for the prevention of Echinococcus granulosus infection in humans include proper sanitation and hygiene practices, emphasizing thorough handwashing after contact with dogs, with their feces or with soil contaminated with the parasite’s eggs. In at-risk areas, it is important to wash vegetables that are eaten raw and to use safe water. Infected livestock organs should be disposed of safely and should not be fed to dogs or other canids.

You can help prevent hydatid disease (Echinococcus granulosus) by limiting areas where your dogs are allowed and don’t let your animals eat meat infected with Echinococcus granulosus cysts.

If you live in an area where Echinococcus granulosus (cystic echinococcosis) or hydatid disease is found in sheep or cattle, take the following precautions to avoid infection:

Wash your hands with soap and warm water after handling dogs, and before handling food.
Teach children the importance of washing hands to prevent infection.
Do not consume any food or water that may have been contaminated by fecal matter from dogs. This might include grass, herbs, greens, or berries gathered from fields.
Don’t allow your dogs to wander freely or to capture and eat raw meat from sheep, cattle, pigs, and goats.
Control stray dog populations.
Don’t home slaughter sheep and other livestock.
Prevent dogs from feeding on the carcasses of infected sheep.
If you think your pet may have eaten infected meat, consult your veterinarian about the possible need for preventive treatments.

Hydatid disease signs and symptoms

As hydatid disease (Echinococcus granulosus) advances and the cysts get larger, symptoms may include:

Pain in the upper right part of the abdomen (liver cyst)
Increase in size of the abdomen due to swelling (liver cyst)
Bloody sputum (lung cyst)
Chest pain (lung cyst)
Cough (lung cyst)
Severe allergic reaction (anaphylaxis) when cysts break open

Hydatid disease can go undetected for many years due to the slow growth and development of cysts and host’s immune system ⁵⁶, ⁵⁷. According to Wen et al ⁴, cystic growth is faster in patients with AIDS, indicating that an immunosuppressive state may play a role in disease advancement.

Depending on the size and location, Echinococcus granulosus cysts can eventually exert pressure on nearby structures, producing abdominal discomfort and pain ⁵⁸, ³⁹. Symptoms develop slowly. Epigastric and/or right hypochondriac pain, nausea and vomiting are frequently observed. 85–90% of the cases have single organ involvement, and more than 70% of patients have a single cyst. Based on the organ in which the cyst settles and the environment they affect, they may show various clinical manifestations changing from cholangitis with biliary ruptures, portal hypertension, biliary obstruction and fistulae, and ascites to abscess formation ⁵⁹.

Hydatic cysts in the liver can compress bile ducts, causing obstruction that can manifest as obstructive jaundice, abdominal pain, anorexia, and itch ⁶⁰. Liver involvement usually presents with symptoms when the cyst size is large (> 10 cm) in diameter or when 70% of the organ volume has been taken up by the cyst(s). Common presenting complaints may include right hypochondrial pain, a liver mass, and nausea and vomiting ³⁵, ⁶¹, ⁶². Obstructive jaundice may occur if an adjacent liver cyst compresses the biliary system ³⁶. Physical examination findings may exhibit hepatomegaly or abdominal distension ⁴, ⁶³.

Hydatic cysts in the lungs can irritate the membranes leading to chronic cough, shortness of breath, pleuritic chest pain, and coughing up blood ⁶⁴.

Patients with complicated disease may also present with cystic rupture occurring spontaneously or infrequently after blunt abdominal trauma. Although rupture is a rare presentation, it is a potentially fatal complication. Hydatid cyst rupture or leakage can cause immunologic symptoms from elevated levels of immunoglobulins (Ig). IgE, IgG2, and IgG4 have been implicated for allergic reactions such as itch, hives, and anaphylactic shock ⁵⁷. Ruptured cysts can release viable cystic contents and protoscolices into the peritoneum and cause ‘seeding’ of viable protoscolices in the peritoneum resulting in secondary hydatidosis ⁶⁴, ⁶¹. Therefore, infectious symptoms can manifest as sepsis, either due to the primary infection or to a secondary infection from leakage into the biliary tree. In one study, bacterial superinfection was found in 7.3% (37/503) of patients diagnosed with hydatid disease ⁶⁵. Four of these patients developed severe sepsis, out of which two patients died. Bacteria most commonly seen in the liver cyst infections includes E. coli, Enterococcus, and Streptococcus viridans.

Cholangitis may be present due to biliary tree obstruction if ruptured cysts communicate with the biliary system. Free intra-peritoneal rupture may result in an immunological response resulting in an allergic reaction, the most fatal of which is anaphylactic shock ³⁵, ³⁶, ⁶². In rare cases, secondary lung involvement may occur due to the rupture of a liver cyst through the diaphragm ⁶⁶.

Most primary infections in humans consist of a single cyst; however, 20–40% of individuals have multiple cysts or multiple organ involvement ³⁶. Even though infections may be acquired in childhood, most cases of liver and lung cysts become symptomatic and are diagnosed in adult patients because of the slowly growing nature of the echinococcal cyst ³⁶. Only 10–20% of cases are diagnosed in patients younger than 16 years ³⁶. However, cysts located in the brain or an eye can cause clinical symptoms even when small; therefore, most cases of intracerebral echinococcosis are diagnosed in children. In the lungs, ruptured cyst membranes can be evacuated entirely through the bronchi or can be retained to serve as a nidus for bacterial or fungal infection. Dissemination of protoscolices can result in multiple secondary echinococcosis disease. Larval growth in bones is atypical; when it occurs, invasion of marrow cavities and spongiosa is common and causes extensive erosion of the bone ¹⁷.

Hydatid disease complications

Rupture of hydatid cyst may either be spontaneous or more usually after blunt trauma can cause site-specific complications. Cyst may rupture into the biliary system (leading to cholangitis with or without obstructive jaundice and marked eosinophilia), into the peritoneum (leading to anaphylaxis and/or peritoneal dissemination causing secondary hydatidosis) or into the pleura or lung (causing pleural hydatidosis, bronchial fistula, pneumonitis, pneumothorax, pleural effusion, and secondary pleuritis) ⁶⁷, ⁶⁸, ⁶⁹, ⁷⁰.

Hydatid cyst rupture can be of three types ⁷¹:

Contained rupture – only endocyst is torn and cyst contents are confined within pericyst. The size of cyst does not decrease on imaging.
Communicating rupture – there is tearing of endocyst and cyst contents escape via biliary radicals or bronchioles that have been incorporated in pericyst. On imaging, cyst becomes smaller with undulating membrane.
Direct rupture – both endocyst and pericyst rupture causing spillage of contents into peritoneum or pleural space and dissemination of disease.

Hydatid cysts may become infected following bacteremia or via communicating bile ducts, especially when endoscopic retrograde cholangio-pancreatography (ERCP) has been performed. These patients present with high fever, sepsis syndrome and a tender liver. Pressure or mass effect on the bile ducts, portal veins, hepatic veins and inferior vena cava can cause cholestasis, portal hypertension and the Budd-Chiari Syndrome, respectively.

Rupture of echinococcosis cyst can induce an IgE-mediated hypersensitivity reaction in patients, presenting as hives, mucous membrane swelling, and flushing. The hypersensitivity reaction can be life-threatening ⁷².

Hydatid disease diagnosis

The diagnosis of echinococcosis relies mainly on findings by ultrasound imaging and/or other imaging techniques (magnetic resonance imaging [MRI] should be preferred to computed tomography [CT] due to better visualization of liquid areas within the matrix) supported by positive serologic tests ²⁹, ⁷³. Ultrasound surveys have shown that cysts may grow 1 mm to 50 mm per year or persist without changes for years. They may also spontaneously rupture or collapse or disappear ⁷⁴, ⁷⁵, ⁷⁶, ⁷⁷. The sequence of cyst changes during the natural history is still unclear ⁷⁸. Liver cysts appear to grow at a lower rate than lung cysts ⁷⁹. Clinical symptoms usually occur when the cyst compresses or ruptures into neighbouring structures.

The diagnosis of Echinococcus granulosus infection or hydatid disease is suggested by identification of a cyst-like mass in a person with a history of exposure to sheepdogs in areas where the Echinococcus granulosus taperworm is endemic. Hydatid disease (Echinococcus granulosus) must be differentiated from benign cysts, cavitary tuberculosis, mycoses, abscesses, and benign or malignant neoplasms. Noninvasive imaging techniques such as CT scans, MRI, and ultrasound imaging are all used for detecting and defining the extent and condition of avascular fluid-filled cysts in most organs. These techniques have proved valuable for diagnosis and preoperative evaluation by staging the condition of the lesion, the extent of the lesion in reference to other organs and vital structures, and identifying the presence of additional occult lesions. Radiography permits the detection of hydatid cysts in the lungs; however, in other organ sites, calcification is necessary for visualization. Ultrasonography has been widely used for screening, clinical diagnosis, and monitoring of treatment of liver and intra-abdominal cysts. Cyst viability cannot be reliably determined with radiography or parasite antigen detection; calcification can be present in all stages of cysts.

Serologic tests, such as enzyme-linked immunosorbent assay (ELISA) and indirect hemagglutination (IHA) test, are highly sensitive methods for detecting infection. Specific confirmation can be obtained by demonstrating echinococcal antigens by immunodiffusion (arc 5) procedures or immunoblot assays (8-, 21 –kD bands).

Serum liver enzyme tests have low sensitivities, and are frequently unreliable in determining the underlying severity of the infection. Moreover, liver enzyme tests are abnormal in only 40% of hydatid disease infected patients ³⁶. When present, alkaline phosphatase (ALP) is commonly elevated, while aspartate/alanine transaminase ratio and bilirubin levels typically remain within the normal limits ³⁶.

Possible versus probable versus confirmed cystic echinococcosis case

Possible case. Any patient with a clinical or epidemiological history, and imaging findings or serology positive for cystic echinococcosis.
Probable case. Any patient with the combination of clinical history, epidemiological history, imaging findings and serology positive for cystic echinococcosis on two tests.
Confirmed case. The above, plus either (1) demonstration of protoscoleces or their components, using direct microscopy or molecular biology, in the cyst contents aspirated by percutaneous puncture or at surgery, or (2) changes in ultrasound appearance, e. g. detachment of the endocyst in a CE1 cyst, thus moving to a CE3a stage, or solidification of a CE2 or CE3b, thus changing to a CE4 stage, after administration of albendazole (at least 3 months) or spontaneous.

Antibody Detection

Indirect hemagglutination (IHA), indirect fluorescent antibody (IFA) tests, and enzyme immunoassays (EIA) are sensitive tests for detecting antibodies in serum of patients with hydatid disease (Echinococcus granulosus); sensitivity rates vary from 60% to 90%, depending on the characteristics of the cases and antigens used. At present, the best available serologic diagnosis is obtained by using combinations of tests. Enzyme immunoassays (EIA) or indirect hemagglutination (IHA) can be used for screening; positive reactions should be confirmed by immunoblot assay. Indirect hemagglutination (IHA) testing has a sensitivity of 90%; however, if the result is positive, it may remain positive for several years after that ⁸⁰. Western blot (WB) serology for liver hydatid disease has a high sensitivity of 80–100% and a specificity of 88–96%. Drawbacks with Western blotting are that the test is expensive, and sensitivity rates reduce dramatically in extra-hepatic disease ³⁴, ⁸¹, ⁸². As some tests may cross-react with sera from persons with cysticercosis, clinical and epidemiological information should also be used to support diagnosis. A commercial enzyme immunoassays (EIA) kit is available in the United States.

Sensitivity of serum antibody detection using indirect hemagglutination (IHA), enzyme-linked immunosorbent assay (ELISA), or latex agglutination, with hydatid cyst fluid antigens, ranges between 85 and 98% for liver cysts, 50–60% for lung cysts and 90–100% for multiple organ cysts ⁸³, ⁸⁴, ⁸⁵. Specificity of all tests is limited by cross-reactions due to other cestode infections (Echinococcus multilocularis and Taenia solium), some other helminth diseases, cancers, liver cirrhosis and presence of anti-P1 antibodies.

Enzyme-linked immunosorbent assay (ELISA) is considered the gold standard serological test for liver-only hydatid involvement ¹³. Immunoglobulin G (IgG) ELISA detects Echinococcus granulosus-specific antigen with a sensitivity of 93.5% and specificity of 89.7% ⁸⁶, ³⁵, ⁶¹, ⁶². However, seronegative results are often found in early-stage cysts where the Echinococcus granulosus antigens are contained in the endocyst. The antigens are then sealed off from the host’s immunological response to the parasitic infection. The same lack of immune response occurs in the late stages of the disease process, where the cysts are calcified, often resulting in a seronegative result ⁶¹.

Confirmatory tests must be used (arc-5 test; Antigen B (AgB) 8 kDa/12 kDa subunits or EgAgB8/1 immunoblotting) in dubious cases ⁸³, ⁸⁴. Immunoblotting may be used as a first-line test and is best for differential diagnosis ⁸⁷. Mass screening in populations at risk optimally deploys ultrasound and serology ⁸⁸.

Detection of parasite-specific IgE or IgG4 has no significant diagnostic advantage. Both parasite-specific IgE or IgG4, as well as eosinophil count, are more elevated after rupture/leakage of cysts ⁸⁹. Complete blood count tests may be helpful, as eosinophilia may be present in 40% of patients ⁶⁴.

Hydatid disease ultrasound classification

For hepatic hydatid disease or liver hydatid disease, the World Health Organization Informal Working Group (WHO-IWGE) developed an ultrasound classification to stage liver echinococcosis and allow a natural grouping of the cysts into three relevant groups: active (CE1 and CE2), transitional (CE3) and inactive (CE4 and CE5) ⁹⁰:

CL: “Cystic Lesion” stage (undifferentiated).

“Cystic Lesion” stage is not a cystic echinococcosis stage but indicates a cyst that could be a suspected young echinococcal cyst. Cystic Lesion (CL) is described as an unilocular cyst with anechoic content, without double wall sign, nor evident signs of non-parasitic aetiology (e.g. clear features of a biliary cyst). If serological and/or epidemiological criteria apply, this is a suspected cystic echinococcosis case. The etiological diagnosis of Cystic Lesion (CL) cysts (cystic echinococcosis or biliary cyst) necessitates further diagnostic steps ⁹¹, ⁹², ⁹³.

Active cysts, likely to contain viable protoscoleces:

CE1: Active, unilocular, liquid content.
- Well-defined univesicular cyst, with round or oval shape, anechoic content, posterior acoustic enhancement, with or without low intensity floating echoes upon decubitus change (moving “hydatid sand”) and with visible pathognomonic “double wall sign” consisting in the inner hyperechoic laminated layer and outer hypoechoic adventitial layer.
CE2: Active, multivesicular, liquid content.
- Well-defined multivesicular cyst, with round or oval shape, posterior acoustic enhancement, one or more daughter cysts filling in part or completely the fluid-filled cyst; the pathognomonic “honeycomb” appearance is provided by the thin, regular, continuous and avascular clearly distinguishable adjacent walls of juxtaposed daughter cysts (giving a
  septated appearance), without solid content.
CE3a: Transitional unilocular, liquid content with detached parasitic layers.
- Well-defined univesicular cyst with round or oval shape, posterior acoustic enhancement, and with partial or complete detachment of the laminated layer, visible as a hyperechoic thin and regular layer floating in the anechoic cyst content, giving a pathognomonic appearance, referred to as the “water lily sign”. The whole layer must be identified as a continuous hyperechogenic structure, in different views. Low-intensity floating echoes upon decubitus change (moving “hydatid sand”) may be present.
CE3b: Active multivesicular cyst, with partially solid content with daughter cysts.
- Well-defined multivesicular cyst with round or oval shape, posterior acoustic enhancement, and heterogeneous structure, encompassing avascular solid components and hypoechoic folded structures deriving from degenerating layers and one or more round daughter cysts with anechoic content, giving the pathognomonic “Swiss cheese” appearance.

Inactive Stages:

CE4: Solid content.
- Well-defined round or oval mass with or without posterior acoustic enhancement and with heterogeneous avascular solid content formed by the degenerated cyst layers, and hypoechoic folded structures deriving from degenerating layers in the mass and giving the pathognomonic “ball of wool” or “canalicular” or “cerebroid” appearance. Unlikely to contain viable protoscoleces.
CE5: Solid content with eggshell calcified wall.
- Well-defined round or oval mass with posterior acoustic shadow deriving from a complete or nearly complete egg-shell calcified wall, and heterogeneous avascular solid content (when acoustic shadow allows visualization) formed by the degenerated cyst layers and hypoechoic folded structures deriving from degenerating layers in the mass and giving the pathognomonic “ball of wool” or” canalicular” appearance. Non-viable.

Note: All cystic echinococcosis cyst stages can show some wall calcification, so this feature, per se, does not indicate viability or non-viability of the cyst.

Stages CE1 and CE2 indicate active disease; stage CE3 indicates a transitional stage where the cyst has suffered a compromise, whereas CE4 and CE5 indicate inactive disease.

Radiography can be used to detect calcifications in up to 30% of cases. The calcifications are typically ring-like and can progress throughout all stages of the disease ⁹⁴.

CT imaging is highly sensitive and serves a vital role in cases where ultrasonography is difficult (e.g., obese patients). It’s also crucial in the perioperative period, as it’s excellent at detecting complications, including cyst rupture, underlying infection, and biliary or vascular involvement ⁹⁵.

Other modalities used for diagnosis include ultrasound-guided fine needle aspiration (in seronegative cases with inconclusive imaging) and endoscopic retrograde cholangiopancreatography (both diagnostic and therapeutic for cases affecting the biliary tree) ⁹⁶.

Figure 7. World Health Organization echinococcosis ultrasound classification

WHO echinococcosis ultrasound classification

[Source ⁹⁰ ]

Figure 8. New Echinococcosis Imaging and Classification

Footnotes: New classification of ultrasound images and the associated classification of computed tomography (CT) images in alveolar echinococcosis have been proposed and are currently being tested on patients at European and Chinese centers in order to evaluate their usefulness for diagnosis and follow-up ⁹⁷, ⁹⁸.

[Source ⁴ ]

Hydatid disease treatment

Hydatid disease (Echinococcus granulosus) management approach is primarily guided by an assessment of the signs and symptoms of the patient at presentation and involves patient factors such as age and comorbidities, and access to health infrastructures. The treatment of choice for uncomplicated cystic echinococcosis (Echinococcus granulosus) is primarily based on the imaging characteristics of the cyst, following a stage-specific approach (when applicable), and on the health care infrastructure and human resources available ⁹⁹.

Patients with small cysts or multiple cysts in several organs can be treated successfully with albendazole.

Praziquantel may be useful preoperatively or in case of spillage of cyst contents during surgery ³⁰.

Figure 9. Liver hydatid disease surgical approaches

Footnotes: Surgical approaches for liver cystic echinococcosis vary from minimally invasive percutaneous approaches (PAIR) to more invasive surgical treatment options, which include partial cystectomy, total cystectomy and hepatic resection.

[Source ¹³ ]

World Health Organization (WHO) guidelines for cystic echinococcosis treatment

World Health Organization (WHO) 2025 guidelines for cystic echinococcosis treatment ¹⁰⁰, ¹⁰¹:

The “Watch and wait” approach can be an option in cases in which the cysts are uncomplicated (stages CE4 and CE5), given that long-term follow-up with ultrasonography can be ensured.
Medical treatment with benzimidazoles is indicated for CE1 and CE3a cysts smaller than 5 cm in the liver and lung, patients with cysts in two or more organs, and inoperable patients. Benzimidazoles are also used following surgery or percutaneous procedures to prevent recurrence. Albendazole is currently the drug of choice at a dose of 10 to 15 mg/kg/day. Mebendazole at a dose of 40 to 50 mg/kg/day is another therapeutic option. Medical treatment with benzimidazole is contraindicated in cysts vulnerable to rupture and early pregnancy. Duration of treatment is based on the clinical situation and can range from 1 to 6 months.
Surgery is the modality of choice for complicated cysts. It is necessary for the removal of large CE2-CE3b cysts, superficial cysts that may rupture with trauma or spontaneously, infected cysts, cysts with biliary tree communication, and cysts exerting pressure on adjacent organs.
PAIR (Puncture, Aspiration, Injection, Re-aspiration) procedure is an ultrasound-guided, minimally invasive modality used in hepatic and other abdominal cysts. Indications include inoperable patients, relapsing cases after surgery, and failure to respond to medical treatment. It provides the best results in CE1 and CE3a cysts over 5 cm and is used in combination with medical therapy (benzimidazole). It is contraindicated in for CE2, CE3b, CE4, and CE5 cysts. Physicians performing this procedure must be equipped to deal with the potential anaphylactic shock. Other percutaneous treatments can be used but are usually reserved for CE2 and CE3b cysts.

Uncomplicated liver cystic echinococcosis cysts: types CE1 or CE3a < 5 cm

In patients with uncomplicated hepatic cyst types CE1 or CE3a < 5 cm, treatment with albendazole is suggested. This recommendation is applicable in any tier (see Tier footnotes below).
Albendazole should be given orally, at a dosage of 10–15 mg/kg/day in two divided doses (up to 400 mg twice a day), with a fat rich meal to increase its bioavailability ⁹⁶. It should be administered continuously, without the monthly treatment interruptions recommended in the 1980s. The treatment duration depends on the individual situation, stage and size of the cystic echinococcosis cyst. Current recommendations suggest continuous treatment for 3–6 months ¹⁰². It is important to use high-quality albendazole that contains the required amount of bioavailable drug.
Albendazole is contraindicated in cysts at risk of rupture and in the first trimester of pregnancy ⁹⁶. Later in pregnancy, potential benefits may warrant use of albendazole despite potential risks. Contraceptive measures are necessary for women of reproductive age while on long-term albendazole. Benzimidazoles must be used with caution in patients with chronic hepatic disease and avoided in those with bone-marrow depression. Monitoring of side-effects is based on liver enzymes for hepatotoxicity and blood cell count.
Follow-up imaging at 3–6 months and thereafter once a year for a minimum of 5 consecutive years after inactivation may help evaluate the success of treatment and monitor for any recurrence of the cysts.
A lack of response is defined as an absence of cyst changes after 3 months of treatment (detachment of the parasitic layers from the outer cyst wall, size reduction, or stage modification). Complete response should be evaluated not earlier than 12 months after treatment end.
Based on expert opinion, if there is a lack of response to an initial course of albendazole, a repeat course of albendazole could be considered.

Uncomplicated liver cystic echinococcosis cysts: types CE1 or CE3a 5 cm to 10 cm

In patients with uncomplicated hepatic cyst types CE1 or CE3a 5cm to 10cm, PAIR (Puncture, Aspiration, Injection, Re-aspiration) combined with albendazole is suggested. PAIR (Puncture, Aspiration, Injection, Re-aspiration) should not be used if biliary communication is present. This recommendation requires tier 3 or tier 4 settings (see Tier footnotes below).
PAIR (Puncture, Aspiration, Injection, Re-aspiration) is only recommended where there is no biliary communication. If bile-stained cyst fluid is aspirated (the assessment is made through visual inspection of aspirate for bile contamination and checking for bilirubin in the aspirated cyst fluid) or contrast is observed in the biliary tract after having been injected into the cyst during a planned PAIR procedure, it is strongly recommended that injection of a protoscolecidal agent after aspiration is not performed. An alternative treatment is percutaneous drainage (S-CAT) without injection of protoscolecidal agent and prolonging administration of albendazole to 6 months. Surgery or medical management can also be considered.
Standard practice is to give albendazole for 1–7 days prior to PAIR (Puncture, Aspiration, Injection, Re-aspiration) and then continue for 1–3 months post-PAIR ¹⁰³, at a dose of 10–15 mg/kg/day (up to 400 mg twice a day) in two divided doses with a fat-rich meal to increase its bioavailability; duration can be extended if considered appropriate. It is important to use high-quality albendazole (branded or generic) that contains the required amount of bioavailable drug. A two-week post-procedure course of praziquantel in addition to albendazole may be considered if there is spillage of cyst contents.
For larger hepatic cystic echinococcosis cysts, especially for CE1 cyst types which are more prone to albendazole-related perforation, albendazole should be given for a shorter period before procedure (sometimes only once) to reduce the risk of perforation.
After PAIR, patients must be closely monitored for potential complications including anaphylaxis, infection or bleeding. Monitoring of adverse events to albendazole treatment should also be implemented.
Albendazole is contraindicated in cysts at risk of rupture and in the first trimester of pregnancy ⁹⁶. Later in pregnancy, potential benefits may warrant use of albendazole despite potential risks. Contraceptive measures are necessary for women of reproductive age while on long-term albendazole. Benzimidazoles must be used with caution in patients with chronic hepatic disease and avoided in those with bone-marrow depression. Monitoring of side-effects is based on liver enzymes for hepatotoxicity and blood cell-count.
In cases where surgical intervention is chosen for individuals with uncomplicated CE1 or CE3a cysts 5–10 cm in size, the surgical procedure can be performed either through an open or laparoscopic approach, depending on the location of the cyst, the expertise of the surgical team and the availability of resources. For any patient in which surgery is an option, individual patient factors such as general health, comorbidities and age should be considered before the final decision is made.
Follow-up imaging at 3–6 months and thereafter once a year for a minimum of 5 consecutive years after inactivation may help evaluate the success of treatment and monitor for any recurrence of the cysts.
A lack of response is defined as an absence of cyst changes after 3 months of treatment (detachment of the parasitic layers from the outer cyst wall, size reduction, or stage modification). Complete response should be evaluated not earlier than 12 months after treatment end.

Uncomplicated liver cystic echinococcosis cysts: types CE1 or CE3a > 10 cm

In patients with uncomplicated hepatic cyst types CE1 or CE3a > 10 cm, percutaneous treatment combined with albendazole is suggested. PAIR (Puncture, Aspiration, Injection, Re-aspiration) is suggested rather than standard catheterization or surgery. PAIR (Puncture, Aspiration, Injection, Re-aspiration) should not be used if biliary communication is present. This recommendation requires tier 3 or tier 4 settings (see Tier footnotes below).
Many health care settings may not have the appropriate expertise and resources available to safely deliver PAIR (Puncture, Aspiration, Injection, Re-aspiration), Standard Catheterization (S-CAT) or surgery. In these settings, the safest treatment option utilizing available expertise and resources with consideration of patient treatment preferences is recommended.
PAIR (Puncture, Aspiration, Injection, Re-aspiration) is only recommended where there is no biliary communication, and cysts > 10 cm have high risk of such fistulas, so special care should be taken. If bile-stained cyst fluid is aspirated (the assessment is made through visual inspection of aspirate for bile contamination and checking for bilirubin in the aspirated cyst fluid) or contrast is observed in the biliary tract after having been injected into the cyst during a planned PAIR procedure, it is strongly recommended that injection of a protoscolecidal agent after aspiration is not performed. An alternative treatment is percutaneous drainage (S-CAT) without injection of protoscolecidal agent and prolonging the administration of albendazole to 6 months. Surgery or medical management can also be considered.
Standard practice is to give albendazole for 1–7 days prior to the percutaneous treatment and then continue for 1–3 months post percutaneous treatment ¹⁰³, at a dose of 10–15 mg/kg/day (up to 400 mg twice a day) in two divided doses with a fat-rich meal to increase its bioavailability; duration can be extended if considered appropriate. It is important to use high-quality albendazole (branded or generic) that contains the required amount of bioavailable drug. A 2-week post-procedure course of praziquantel in addition to albendazole may be considered if there is spillage of cyst contents.
For larger hepatic cystic echinococcosis cysts, especially for CE1 cyst types which are more prone to albendazole- related perforation, albendazole should be given for a shorter period before procedure (sometimes only once) to reduce the risk of perforation.
After percutaneous treatments, patients must be closely monitored for potential complications including anaphylaxis, infection or bleeding. Monitoring of adverse events to albendazole should also be implemented.
Albendazole is contraindicated in cysts at risk of rupture and in the first trimester of pregnancy ⁹⁶. Later in pregnancy, potential benefits may warrant use of albendazole despite potential risks. Contraceptive measures are necessary for women of reproductive age while on long-term albendazole. Benzimidazoles must be used with caution in patients with chronic hepatic disease and avoided in those with bone-marrow depression. Monitoring of side-effects is based on liver enzymes for hepatotoxicity and blood cell count.
In cases where surgical intervention is chosen for individuals with uncomplicated CE1 or CE3a cysts > 10 cm in size, the surgical procedure can be performed either through an open or laparoscopic approach, depending on the location of the cyst, the expertise of the surgical team and the availability of resources. For any patient in which surgery is an option, individual patient factors such as general health, co-morbidities and age should be considered before the final decision is made.
Follow-up imaging at 3–6 months and thereafter once a year for a minimum of 5 consecutive years after inactivation may help evaluate the success of treatment and monitor for any recurrence of the cysts.
A lack of response is defined as an absence of cyst changes after 3 months of treatment (detachment of the parasitic layers from the outer cyst wall, size reduction, or stage modification). Complete response should be evaluated not earlier than 12 months after treatment end.

Uncomplicated liver cystic echinococcosis cysts: types CE2 or CE3b ≤ 5 cm

In patients with uncomplicated hepatic cyst types CE2 or CE3b ≤ 5 cm, initial treatment with albendazole alone is suggested. This recommendation is applicable in any tier (see Tier footnotes below).
Albendazole should be given orally, at a dosage of 10–15 mg/kg/day in two divided doses (up to 400 mg twice a day), with a fat-rich meal to increase its bioavailability ⁹⁶. Albendazole should be administered continuously, without the monthly treatment interruptions recommended in the 1980s. The treatment duration depends on the individual situation, stage and size of the cystic echinococcosis cyst. Current recommendations suggest continuous treatment for 3–6 months ¹⁰². It is important to use high-quality albendazole that contains the required amount of bioavailable drug.
Albendazole is contraindicated in cysts at risk of rupture and in the first trimester of pregnancy ⁹⁶. Later in pregnancy, potential benefits may warrant use of albendazole despite potential risks. Contraceptive measures are necessary for women of reproductive age while on long-term albendazole. Benzimidazoles must be used with caution in patients with chronic hepatic disease and avoided in those with bone-marrow depression. Monitoring of side-effects is based on liver enzymes for hepatotoxicity and blood cell count.
Follow-up imaging at 3–6 months and thereafter once a year for a minimum of 5 consecutive years after inactivation may help evaluate the success of treatment and monitor for any recurrence of the cysts.
A lack of response is defined as an absence of cyst changes after 3 months of treatment (detachment of the parasitic layers from the outer cyst wall, size reduction or stage modification). Complete response should be evaluated not earlier than 12 months after end of treatment.
Since albendazole alone is known to have a higher risk of relapse, in the event of non-response at 3 months, based on expert opinion, surgery (non-radical or radical approaches) should be offered along with continued albendazole. For any patient in which surgery is an option, individual patient factors such as general health, comorbidities and age should be considered before the final decision is made.

Uncomplicated liver cystic echinococcosis cysts: types CE2 or CE3b > 5 cm

In patients with uncomplicated hepatic cyst types CE2 or CE3b > 5 cm, surgery combined with albendazole is suggested. This can be open surgery (in tiers 2–4) or laparoscopy (in tiers 3–4) (see Tier footnotes below).
For any patient in which an invasive procedure, especially surgery, is an option, individual patient factors such as general health, comorbidities and age should be considered before the final decision is made.
The choice between open or laparoscopic surgery will depend on the setting infrastructure, availability of laparoscopy, site of the cyst and cyst characteristics, expertise and experience of the local clinical team, surgeon’s preference and patient choice. Laparoscopy is favoured for peripheral, superficial cysts, especially in paediatric cases, and open surgery should be chosen when a cyst is deep or in other complicated scenarios.
Surgical challenges include inaccessibility when dealing with small cysts deep within the liver parenchyma, particularly in segments 7 and 8, and in individuals with underlying comorbidities.
If opting for Mo-CAT, it is crucial to reduce the risk of recurrence by ensuring thorough removal of all cyst content and the germinal layer. T2-weighted MRI in addition to ultrasound and cavitography can be used to monitor the efficacy of treatment between sessions.
Standard practice is to give albendazole for 1–7 days prior to the surgical procedure and then continue for 1–3 months post procedure, at a dose of 10–15 mg/kg/day (up to 400 mg twice a day) in two divided doses with a fat-rich meal to increase its bioavailability; duration can be extended if considered appropriate. It is important to use high-quality albendazole that contains the required amount of bioavailable drug. A two-week post-procedure course of praziquantel in addition to albendazole may be considered if there is spillage of cyst contents.
For the larger hepatic cystic echinococcosis cysts, albendazole should be given for a shorter period before procedure (sometimes only once) to reduce the risk of perforation.
After surgery, patients must be closely monitored for potential complications including anaphylaxis, infection or bleeding. Monitoring of adverse events to albendazole should also be implemented.
Albendazole is contraindicated in cysts at risk of rupture and in the first trimester of pregnancy ⁹⁶. Later in pregnancy, potential benefits may warrant use of albendazole despite potential risks. Contraceptive measures are necessary for women of reproductive age while on long-term albendazole. Benzimidazoles must be used with caution in patients with chronic hepatic disease and avoided in those with bone-marrow depression. Monitoring of side-effects is based on liver enzymes for hepatotoxicity and blood cell count.
Follow-up imaging at 3–6 months and thereafter once a year for a minimum of 5 consecutive years after inactivation may help evaluate the success of treatment and monitor for any recurrence of the cysts.
A lack of response is defined as an absence of cyst changes after 3 months of treatment (detachment of the parasitic layers from the outer cyst wall, size reduction or stage modification). Complete response should be evaluated not earlier than 12 months after treatment end.

Use of praziquantel combined with albendazole post-percutaneous/surgical procedures for hepatic cyst types CE1, CE2, CE3a, CE3b

In cystic echinococcosis patients undergoing percutaneous or surgical interventions, when spillage is suspected or has occurred, the combination praziquantel and albendazole is suggested.
In case of suspected or ascertained cyst fluid spillage, albendazole should be given at a dose of 10–15 mg/kg/day in two divided doses (up to 400 mg twice a day) for a minimum of 3 months, usually, 6–12 months after the intervention, as considered appropriate by the clinician.
Praziquantel should be given at a dose of 40–50 mg/kg/day divided into two daily doses for 2 weeks after the intervention. Because praziquantel does not have an effect on the cyst (as compared to albendazole), 2 weeks are suggested. However, the period can be increased to a maximum of 4 weeks if considered appropriate by the clinician.
Albendazole and praziquantel can be given simultaneously during a fat-rich meal to increase their bioavailability.
Some clinicians use praziquantel in combination with albendazole for 2 weeks prior to procedure ¹⁰⁴. More evidence is needed to make this practice a recommendation.

Uncomplicated lung cystic echinococcosis cysts ≤ 5 cm

In patients with uncomplicated active lung cystic echinococcosis cysts < 5 cm, surgery is suggested. Albendazole should not be given before surgery. When spillage is suspected or has occurred, albendazole after surgery is suggested. Lung surgery requires tier 4 settings (see Tier footnotes below).
Medical treatment with albendazole should only be contemplated if surgery is medically contraindicated or not feasible due to specific patient circumstances. During medical treatment, regular monitoring for secondary infection, or expectoration of laminated layer, is mandated. T2-weighted MRI can be applied to monitor the inactivation of the cyst over time.
For any patient in which an invasive procedure, especially surgery, is an option, individual patient factors such as general health, comorbidities and age should be considered before the final decision is made.
Standard practice is not to give albendazole prior to the surgical procedure due to the perceived risk of rupture in the case of lung cysts. If there are concerns of intraoperative spillage, then give albendazole for 1–3 months post procedure, at a dose of 10–15 mg/kg/day (up to 400 mg twice a day) in two divided doses with a fat-rich meal to increase its bioavailability; duration can be extended if considered appropriate. It is important to use high-quality albendazole, that contains the required amount of bioavailable drug. A 2-week post-procedure course of praziquantel in addition to albendazole may be considered if there is spillage of cyst contents.
After surgery, patients must be closely monitored for potential complications including anaphylaxis, infection, prolonged air leak or bleeding. Monitoring of adverse events to albendazole should also be implemented.
Albendazole is contraindicated in the first trimester of pregnancy ⁹⁶. Later in pregnancy, potential benefits may warrant use of albendazole despite potential risks. Contraceptive measures are necessary for women of reproductive age while on long-term albendazole. Benzimidazoles must be used with caution in patients with chronic hepatic disease and avoided in those with bone-marrow depression. Monitoring of side-effects is based on liver enzymes for hepatotoxicity and blood cell count.
Follow-up imaging at 3–6 months and thereafter once a year for a minimum of 5 years after inactivation may help evaluate the success of treatment and monitor for any recurrence of the cysts.
A lack of response is defined as an absence of cyst changes after 3 months of treatment (detachment of the parasitic layers from the surrounding lung tissue, size reduction or morphological change). Complete response should be evaluated not earlier than 12 months after treatment end.

Uncomplicated inactive liver cysts are not covered in these guidelines. Current practice is to “watch and wait”, that is, to follow-up with imaging (ultrasonography or MRI). Surgery should be avoided as far as possible unless the inactive cyst is causing complications (e.g. cyst causing portal hypertension).

Patients with multiple hepatic cysts, with hepatic cysts in different stages, and with two or more organs involved (multi-organ involvement) will require individualized management ¹⁰⁰, ¹⁰¹.

Tiers Footnotes:

Tier 1: Medical doctor, basic laboratory capacity, ultrasound referral availability.
Tier 2: Tier 1 plus general surgeon, anaesthetic and operating theatre capacity, on-site ultrasonography.
Tier 3: Tier 2 plus laparoscopic surgeon, physician trained in PAIR, Standard Catheterization (S-CAT), CT and fluoroscopy capacity.
Tier 4: Tier 3 plus thoracic surgery and interventional radiology capacity, MRI and MRCP capacity, advanced laboratory capacity.

Antiparasitic therapy

Antiparasitic therapy confers numerous benefits for the patient. It can be used as monotherapy for the uncomplicated CE1 and CE3a liver cysts less than 5 cm in diameter and multiple liver cysts or multiorgan involvement in the inoperable candidate ⁴, ⁶², ⁶⁶. Antiparasitic therapy is also used as a neoadjuvant agent before percutaneous or surgical therapy to chemically sterilize the parasite to render the cyst inactive, reduce the cystic wall tension and reduce the risk of intra-operative viable cyst rupture ³⁶, ⁶⁶. Due to the increased bioavailability and improved absorption from the gut, albendazole is the preferred anthelmintic agent of choice for liver hydatid disease ⁴, ⁶², ¹⁰⁵, ¹⁰⁶. Albendazole is administered at a 12-hourly dosage of 10–15 mg/kg/day ⁴, ⁶⁶. There has been no consensus on the schedule and length of anthelmintic in the neoadjuvant and adjuvant setting, with various authors making different recommendations ⁴. Akhan et al ¹⁰⁷ recommended albendazole therapy be given for Puncture, Aspiration, Injection and Re-aspiration (PAIR), 1 week before and 1 month after treatment. Velasco-Tirado et al ¹⁰⁶ recommended that albendazole be used pre-operatively anytime from 3 months to 1 day before surgical or percutaneous intervention and continued 1–3 months after the procedure. Wen et al ⁴ suggested initiating albendazole therapy 1 week before intervention and continuing for up to 2 months after the procedure. A comprehensive regime to administer for uncomplicated cysts is albendazole therapy, administered at least 3 days pre-operatively and continued post-operatively for 4–8 weeks. In complicated cysts or intra-operative spillage, the post-operative duration may be extended to 3–6 months ³⁴, ³⁶, ⁶⁶.

A continuous treatment regime should be administered with the previous regime of cyclical administration avoided in current practice ³⁴, ⁶⁶. Clinicians must be prudent about the side effects of albendazole, such as hepatic dysfunction, alopecia and agranulocytosis. Patients should be monitored regularly with white cell count and liver function tests ⁶¹, ⁶⁶. Blood tests should be done on days 5, 14 and 28 after initiation, biweekly and monthly, if therapy is ongoing ³⁴, ³⁶, ⁶¹. It should be noted that albendazole is contraindicated in early pregnancy as it is teratogenic in rats and rabbits ⁸⁶, ⁶⁶.

Some authors have postulated that combination therapy with praziquantel increases the albendazole metabolite’s serum and cystic fluid levels compared with patients receiving albendazole monotherapy ¹⁰⁶, ³⁴. However, due to the lack of more robust evidence with further randomized control trials, it is not a widely accepted practice ¹⁰⁶, ⁶⁶, ¹⁰⁵.

Albendazole

Adult dosage 400 mg orally twice a day for 1-6 months
Children dosage 10-15 mg/kg/day (max 800 mg) orally in two doses for 1-6 months

Albendazole treatment during pregnancy

Albendazole is a pregnancy category C drug. There are limited data on the use of albendazole in pregnant women. The available evidence suggests no difference in congenital abnormalities in the children of women accidentally treated with albendazole during mass drug administration (MDA) campaigns compared with those who were not. In MDA campaigns for which the World Health Organization (WHO) has determined that the benefits of treatment outweigh the risks, WHO allows use of albendazole in the 2nd and 3rd trimesters of pregnancy. However, healthcare providers should balance the risks of treatment for the fetus with the risks of disease progression in the woman in the absence of treatment.
Pregnancy Category C: Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal, or other) plus there are no controlled studies in women, or studies in women and animals are not available. Prescribe albendazole only if the potential benefits to the woman justify the potential risks to the fetus.
Treatment during lactation
Albendazole is minimally excreted in human milk. WHO has concluded that a single oral dose of albendazole can be given to lactating women.

Albendazole treatment in children

The safety of albendazole in children less than 6 years old is not certain. Studies of the use of albendazole in children as young as one year old suggest that it is safe. According to WHO guidelines for Mass Drug Administration campaigns, children as young as one year of age (able to safely swallow tablets) can take albendazole. These Mass Drug Administration campaigns have treated many children under six years old with albendazole, albeit at a reduced dose.

Mebendazole

Adult dosage 40 – 50 mg/kg body weight per day continuously for several months. Duration of treatment is based on the clinical situation and can range from 1 to 6 months.

Mebendazole treatment during pregnancy

Mebendazole is a pregnancy category C drug. Data on the use of mebendazole in pregnant women are limited. The available evidence suggests no difference in congenital anomalies in the children of women treated with mebendazole during mass drug administration (MDA) campaigns compared with those who were not. In MDA campaigns in countries where soil-transmitted helminths are common, World Health Organization (WHO) has determined that the benefits of treatment outweigh the risks and WHO allows use of mebendazole in the 2nd and 3rd trimesters of pregnancy. However, in a pregnant woman infected with a soil-transmitted helminth, balance the risks of treatment for the fetus with the risks of disease progression in the woman in the absence of treatment.
Pregnancy Category C: Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal, or other) plus there are no controlled studies in women, or studies in women and animals are not available. Prescribe mebendazole only if the potential benefits to the woman justify the potential risks to the fetus.
Treatment during lactation

Mebendazole is minimally excreted in breast milk. WHO classifies mebendazole as compatible with breastfeeding and allows its use in lactating women.

Mebendazole treatment in children

The safety of mebendazole in children is unclear. There are limited data in children under 2 years old. The WHO Model List of Essential Medicines for Children lists mebendazole as an intestinal antihelminthic medicine that can be used for children older than 2 years of age.

‘Watch and wait’ approach

Inactive, degenerating CE4 and all CE5 cysts can be observed with interval ultrasound monitoring without pharmacological or surgical intervention ³⁵, ⁴, ¹⁰⁸.

Percutaneous therapy

Percutaneous approaches for the treatment of liver hydatid disease include PAIR (Puncture, Aspiration, Injection, Re-aspiration), standard catheterization (S-CAT) and modified catheterization technique (MoCat) ³⁴, ¹⁰⁹, ¹¹⁰, ¹¹¹, ¹¹².

PAIR (Puncture, Aspiration, Injection, Re-aspiration) therapy is successfully used for single-compartment cysts, such as CE1 and CE3a cysts less than 10 cm in diameter. Deterrence of PAIR use includes CE2 and CE3b cysts, cases where safe percutaneous cyst localisation with ultrasound guidance is unavailable, and when there is evidence of cysto-biliary communication ¹¹¹, ¹¹³, ³⁵, ⁶⁶, ¹¹⁰.

Standard catheterization (S-CAT) technique is also used for CE1 and CE3a cysts but includes cysts with a diameter greater than 10 cm or those with cystic fluid content of more than 1,000 ml ¹¹⁴, ⁶⁶. If a cysto-biliary communication is found during PAIR, a standard catheterization (S-CAT) technique may be utilised to control biliary drainage ¹¹⁴. One of the drawbacks is the increased duration of hospital stay. Akhan et al ¹⁰⁷ reported a median duration of hospital stay of 2.5 days in 26 patients with standard catheterisation. The catheterization and hospital stay may be prolonged if cysto-biliary communication or cystic infection occurs ¹¹⁵, ¹¹⁶, ¹¹⁷, ¹¹⁴.

A modification to PAIR, the modified catheterization (MoCat) technique, has been utilized for uncomplicated CE2 and CE3b cysts and cysts larger than 10 cm in diameter. As with standard catheterization (S-CAT) technique, modified catheterization (MoCat), results in a longer hospital stay. The modified catheterization (MoCat) approach uses a drainage catheter placed via the Seldinger technique, wherein the cyst contents and membranes can be aspirated. At the end of the procedure, the catheter can be left in place for any ongoing fluid drainage ¹¹⁸, ⁴, ⁸², ⁶⁶, ¹¹⁰, ¹¹².

The first step in the standard PAIR technique is to puncture and aspirate the cyst under ultrasound guidance. A scolicidal agent is then injected into the cystic cavity to sterilise the cyst of any viable protoscoleces and destroy the germinal layer. Various scolicidal agents have been adopted in the use of hydatid disease. Either 20% hypertonic saline or 95% alcohol is recommended with the PAIR technique. The fluid is re-aspirated approximately 15–20 minutes later ⁸⁰, ¹⁰⁸, ⁴, ³⁵. If bile is aspirated, initially after the first puncture, it is suggestive of cysto-biliary communication. Scolicidal injection into the cyst may result in a devastating risk of chemical sclerosing cholangitis and subsequent biliary stricturing and thus should be avoided ⁶², ⁸⁰. There are limited recommendations regarding the management of cysto-biliary communication noted during PAIR. Khuroo ¹¹³ recommends aborting PAIR if ‘yellow cyst fluid’ or ‘positive bilirubin dipstick’ on fluid aspiration occurs. Öztürk et al ¹¹⁰ Turkish consensus report recommends catheterisation after percutaneous therapy can be done for cysts larger than 10 cm and those with biliary content. Catheterization should be left in place for roughly 1 week, with removal only once the fistula output is less than 10 cc. If there is an ongoing or increasing biliary leak, endoscopic retrograde cholangiopancreatography (ERCP) is recommended ¹¹⁰.

Surgery

Surgical options for liver hydatid disease can be divided into conservative and radical approaches ¹¹⁹. The radical approach, which includes total cystectomy and hepatic resection, has been criticised as an aggressive form of therapy associated with significant morbidity for a relatively benign disease process ¹¹⁹, ¹²⁰. It is also a technically demanding surgery and usually requires patients to be operated on in a specialised hepatobiliary unit ⁸⁶, ⁶². For these reasons, the conservative approach with partial cystectomy is more widely adopted. This involves the removal of the cyst content and sterilisation of the residual cavity, together with partial cyst resection, under albendazole cover ¹²¹, ¹²², ⁴.

The partial cystectomy approach uses an appropriate incision to gain access to and expose the liver cyst(s). The surgical field is protected by abdominal swabs soaked in a scolicidal agent (20% hypertonic saline). This helps to prevent contamination in the event of spillage during cyst-content evacuation. The cyst is then punctured, aspirated and instilled with a chosen scolicidal agent. As with PAIR, if bile is aspirated within the cyst, biliary communication is present and the scolicidal agent is avoided. After 15 minutes, the contents are re-aspirated, and the cyst is opened to evacuate the endocyst contents with suction. The cyst is then unroofed by excising the cyst wall outside the liver parenchyma. If a cysto-biliary fistula is noted intra-operatively, it can be managed by suture placement. Once the cystic cavity is evacuated of its contents, the cavity needs to be obliterated either with capitonnage or omentoplasty ³⁴, ¹²², ⁸⁰.

Follow-up period

Follow-up is recommended initially every six months for the first two years, and then once a year depending on the appropriate clinical setting. In hydatid disease, it is difficult to assess the frequency of relapses. Therefore, monitoring with ultrasound is sometimes performed for up to ten years, a duration for which recurrences have been reported despite treatment. In the post-treatment phase, serologic studies, often with Ig levels, are difficult to interpret because they may indicate residual disease as opposed to a disease recurrence. In many cases, they remain elevated despite appropriate therapy or complete resection, which is why they are often used in combination with imaging studies during follow-up to detect cystic activity ¹⁹.

Hydatid disease prognosis

Hydatid disease prognosis is considered generally good with appropriate treatment and if the cysts respond to oral antiparasitic medicines. However, Echinococcus cysts that develop in difficult sites for surgery, such as the heart and spine, have a poorer prognosis ¹⁰. Only 30% to 40% of patients with spinal hydatid disease (Echinococcus granulosus) make a full recovery and the Echinococcosis has high rates of morbidity and mortality ¹²³. Recurrence at the site of the cyst or in other sites occurs in some cases ¹²⁴, ¹²⁵, ¹²⁶, ¹²⁷. Recurrence is one of the major problems in the management of hydatid disease. Recurrence is defined as the appearance of new active cysts following treatment for intra- or extra-hepatic hydatid disease. The failure to achieve permanent elimination of the primary cystic lesion treated is considered to be the cause of local recurrence. Recurrence rates for those with spinal hydatid disease (Echinococcus granulosus) at 24 months was 48% ¹²³. It is for this reason that close follow-up with serial imaging is required.

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Hydatid disease

Hydatid disease

How are dogs, cattle, sheep, and other domestic animals infected with Echinococcus?

Is echinococcosis contagious and can it be transmitted from humans to humans?

What causes hydatid disease

Hydatid disease Life Cycle

Hydatid disease Geographic Distribution

Hydatid disease Hosts

Hydatid disease prevention

Hydatid disease signs and symptoms

Hydatid disease complications

Hydatid disease diagnosis

Antibody Detection

Hydatid disease ultrasound classification

Hydatid disease treatment

World Health Organization (WHO) guidelines for cystic echinococcosis treatment

Uncomplicated liver cystic echinococcosis cysts: types CE1 or CE3a < 5 cm

Uncomplicated liver cystic echinococcosis cysts: types CE1 or CE3a 5 cm to 10 cm

Uncomplicated liver cystic echinococcosis cysts: types CE1 or CE3a > 10 cm

Uncomplicated liver cystic echinococcosis cysts: types CE2 or CE3b ≤ 5 cm

Uncomplicated liver cystic echinococcosis cysts: types CE2 or CE3b > 5 cm

Use of praziquantel combined with albendazole post-percutaneous/surgical procedures for hepatic cyst types CE1, CE2, CE3a, CE3b

Uncomplicated lung cystic echinococcosis cysts ≤ 5 cm

Antiparasitic therapy

Albendazole

Mebendazole

‘Watch and wait’ approach

Percutaneous therapy

Surgery

Follow-up period

Hydatid disease prognosis

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