Echinococcosis

Contents

What is echinococcosis

What is echinococcosis

Echinococcosis also known as hydatid disease or 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. Six species of Echinococcus tapeworms (family Taeniidae) have been identified which infect a wide range of domestic and wild animals, but four are of human health concern: Echinococcus granulosus (which causes cystic echinococcosis), Echinococcus multilocularis (which causes alveolar echinococcosis), and two forms of neotropical echinococcosis Echinococcus vogeli (which cause polycystic echinococcosis) and Echinococcus oligarthrus (which cause unicystic echinococcosis) ², ⁹. Two new species have recently been identified: Echinococcus shiquicus in small mammals from the Tibetan plateau and Echinococcus felidis in African lions, but their zoonotic (animal to human) transmission potential is unknown ². Several studies have shown that echinococcus infections are an increasing public health concern and that they can be regarded as emerging or re-emerging diseases.

The two most important forms of echinococcosis, which are of medical and public health relevance in humans, are cystic echinococcosis (Echinococcus granulosus) and alveolar echinococcosis (Echinococcus multilocularis) caused by larval stages (metacestode) of Echinococcus multilocularis and Echinococcus granulosus respectively ³. While cystic echinococcosis (Echinococcus granulosus) is worldwide, alveolar echinococcosis (Echinococcus multilocularis) is rarer and limited to the Northern hemisphere, but the latest epidemiological data indicate an increasing incidence ⁴, ¹³. Both alveolar echinococcosis (Echinococcus multilocularis) and cystic echinococcosis (Echinococcus granulosus) are caused by infection with Echinococcus tapeworms of the Taeniidae family which have different transmission cycles and different clinical presentations. However, both progress slowly in the liver, the usual primary infection site ⁴, ¹³.

Human infection with Echinococcus granulosus (cystic echinococcosis) leads to the development of one or more hydatid cysts (which are slow growing fluid-filled structures that contain the larvae) 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. The asymptomatic incubation period of cystic echinococcosis (Echinococcus granulosus) can last many years until hydatid cysts grow to a large size that triggers clinical signs, with approximately half of all patients that receive medical treatment for cystic echinococcosis (Echinococcus granulosus) do so within a few years of their initial infection with the Echinococcus granulosus parasite. 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.

Alveolar echinococcosis (Echinococcus multilocularis) is characterized by an asymptomatic incubation period of 5 to 15 years and the slow development of a primary tumor-like lesion which is usually located in the liver. Alveolar echinococcosis (Echinococcus multilocularis) clinical signs include weight loss, abdominal pain, general malaise and signs of liver failure. Alveolar echinococcosis (Echinococcus multilocularis) larval metastases may spread either to organs adjacent to the liver for example, the spleen or distant locations such as the lungs, or the brain following dissemination of the Echinococcus multilocularis parasite via the blood and lymphatic system. If left untreated, alveolar echinococcosis is progressive and fatal with mortality rates ranging between 50% and 75%.

Ultrasound imaging is the technique of choice for the diagnosis of both cystic echinococcosis and alveolar echinococcosis in humans ¹⁴. 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 cystic echinococcosis (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.

Most patients with alveolar echinococcosis (Echinococcus multilocularis) have detectable antibodies. Immunoaffinity-purified Echinococcus multilocularis antigens (Em2) used in enzyme immunoassays (EIA) allow the detection of positive antibody reactions in more than 95% of alveolar echinococcosis. Comparing serologic reactivity to Em2 antigen with that to antigens containing components of both Echinococcus multilocularis and Echinococcus granulosus permits discrimination of patients with alveolar echinococcosis from those with cystic echinococcosis. Combining two purified Echinococcus multilocularis antigens (Em2 and recombinant antigen II/3-10) in a single immunoassay improves sensitivity and specificity. These antigens are included in commercial EIA kit in Europe, but are not available in the United States. Em2 tests are more useful for postoperative follow-up than for monitoring the effectiveness of chemotherapy. Em18-ELISA is considered suitable for monitoring treatment efficacy in alveolar echinococcosis patients.

The serologic diagnosis of polycystic echinococcosis has not been extensively studied as infections with Echinococcus vogeli are very rare. One antigen has been described (Ev2) that distinguishes Echinococcus vogeli from Echinococcus granulosus but not Echinococcus multilocularis.

In seronegative patients with liver image findings compatible with echinococcosis, ultrasound guided fine needle biopsy may be useful for confirmation of diagnosis ¹⁴. 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.

Echinococcosis treatment in humans is complicated because the Echinococcus cysts and the disease progress in differing ways depending on the Echinococcus species, and location. For cystic echinococcosis (Echinococcus granulosus), treatment options 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.

Alveolar echinococcosis (Echinococcus multilocularis) requires antiparasitic drug with or without surgery; radical surgery is the preferred approach in suitable cases, although removal of the entire parasite mass is not always possible. Effective treatment involves benzimidazoles administered continuously for at least two years and patient monitoring for 10 years or more since recurrence is possible. This has inhibited progression of alveolar echinococcosis and reduced lesion size in approximately half of treated cases. Intermittent treatment with albendazole is not recommended.

Figure 1. 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. Alveolar echinococcosis

Footnotes: A man in his thirties from Eastern Europe, who had lived for several years in Norway, developed jaundice and pain below his right costal arch. (a) Patient with alveolar echinococcosis (patient 1). CT abdomen with contrast in venous phase with coronal reconstruction shows a 13 cm large irregular low attenuation lesion with central necrosis and calcification in liver segments 6 and 7. (b) MRCP sequence with coronal maximum intensity projection of liver segments 6 and 7 in the same patient shows innumerable small cysts in all involved liver segments. Serological testing detected antibodies to E. multilocularis, and treatment commenced with oral albendazole. He underwent surgery with extensive resection of the right liver. Macropathology confirmed a large, multilocular cyst (Figure 2), and histological examination showed cysts with laminated membranes, necrosis and fibrosis. Radical surgery was not technically possible, and there were residual lesions around the liver hilus and retroperitoneally. The patient is therefore expected to receive lifelong treatment with albendazole.

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Figure 3. Pulmonary cystic echinococcosis

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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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 echinococcosis

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

The three primary human echinococcosis types are cystic echinococcosis (Echinococcus granulosus), alveolar echinococcosis (Echinococcus multilocularis), and neotropical echinococcosis (Echinococcus vogeli and Echinococcus oligarthrus) ¹⁶. They are caused by different Echinococcus species, and differ on their geographical distribution, transmission cycles and clinical presentation.

Echinococcus granulosus (sensu lato) is the cause of cystic echinococcosis or hydatid disease 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.
Echinococcus multilocularis causes alveolar echinococcosis. Echinococcus multilocularis is only present in the northern hemisphere but it’s becoming increasingly more common. It behaves aggressively, invading tissues like a malignant tumor, primarily in the liver and spreading to other organs, often leading to fatal liver failure if untreated.
Neotropical echinococcosis is quite rare and includes two subtypes: Echinococcus vogeli which causes polycystic growths mainly in the liver and Echinococcus oligarthrus causes the extremely rare unicystic form, which has only been identified in very few human cases. Neotropical echinococcosis have only been reported in rural areas of the tropics in Central and South America. Since neotropical echinococcosis is so rare it is not well understood how long it can remain without symptoms.

Many genotypes of Echinococcus granulosus (cystic echinococcosis) have been identified that differ in their distribution, host range, and some morphological features; these are often grouped into separate species in modern literature. 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). Research on the epidemiology and diversity of these genotypes is ongoing, and no consensus has been reached on appropriate nomenclature thus far.

Cystic echinocccosis

Cystic echinocccosis also known as hydatid disease, hydatid cyst, hydatidosis or echinococcus cysticus is caused by infection with cyst-like Echinococcus granulosus tapeworm larvae, a 7 millimeter long tapeworm found in dogs (definitive host) and sheep, cattle, goats, and pigs (intermediate hosts). The incubation period of cystic echinococcosis (Echinococcus granulosus) is often prolonged for several years and most cases of cystic echinococcosis remain asymptomatic until the Echinococcus granulosus cysts reach a large enough size to cause dysfunction. Most primary Echinococcus granulosus infections in humans consist of a single cyst. The liver is the most common site of the hydatid cysts, followed by the lungs. Echinococcus granulosus cysts in the spleen, kidneys, heart, bone and central nervous system are less common. In secondary echinococcosis, Echinococcus granulosus larval tissue spreads from the primary site and new cysts develop after spontaneous or trauma-induced cyst rupture or after release of viable parasite material during invasive treatment procedures.

Although most infections in humans are asymptomatic, cystic echinococcosis causes harmful, slowly enlarging cysts in your liver, lungs, and other organs of your body that often grow unnoticed and neglected for years. Because the Echinococcus granulosus cysts are slow-growing, infection with cystic echinococcosis (Echinococcus granulosus) may not produce any symptoms for many years. Signs and symptoms may include liver enlargement with or without a palpable mass in the right upper quadrant, right epigastric pain, chest pain, coughing, nausea, and vomiting as a result of the growing cysts. Rupture or leakage of cyst fluid can lead to allergic reactions or even death.

You get cystic echinococcosis or hydatid disease by swallowing the eggs of the Echinococcus granulosus tapeworm. Dogs that eat home-slaughtered sheep and other livestock become infected with the tapeworm Echinococcus granulosus and the tapeworm eggs can be found in their stool. Direct contact with infected dogs, particularly intimate contact between children and their pet dogs, may lead to human infection. Ingestion of soil, water and vegetables contaminated with infected dog feces may also lead to Echinococcus granulosus infections. Echinococcus granulosus eggs can survive snow and freezing conditions.

People at highest risk of cystic echinococcosis (Echinococcus granulosus) include pastoral communities where livestock and dogs interact (dogs are the main definitive host), and those in areas with poor sanitation. Children are particularly vulnerable due to close contact with dogs and poor hygiene.

Humans can also be exposed to these Echinococcus granulosus tapeworm eggs by “hand-to-mouth” transfer or contamination.

By ingesting food, water or soil contaminated with stool from infected dogs. This might include grass, herbs, greens, or berries gathered from fields.
By petting or handling dogs infected with the Echinococcus granulosus tapeworm. These dogs may shed the tapeworm eggs in their stool, and their fur may be contaminated.

See your doctor if you think you may have cystic echinococcosis (hydatid disease). Cystic echinococcosis (Echinococcus granulosus) can be diagnosed with imaging studies such as X-rays or MRI scans, which are helpful to see the Echinococcus granulosus cysts in most of your organs. Blood tests are available to help diagnose an Echinococcus granulosus infection but may not always be accurate. If surgery is necessary, confirmation of the diagnosis can be made by the laboratory.

Alveolar echinococcosis

Alveolar echinococcosis also known as alveococcosis, echinococcus alveolaris, alveolar hydatid, alveolar hydatidosis, alveolar hydatid disease, multilocular hydatid cyst, multilocular hydatid disease or multilocular hydatidosis is caused by parasitic tapeworm infection with the larval stage of Echinococcus multilocularis, a 1 mm to 4 millimeter long tapeworm found in foxes, coyotes, and dogs (definitive hosts) ¹⁵. Small rodents are intermediate hosts for Echinococcus multilocularis. Although cases of alveolar echinococcosis in animals in endemic areas are relatively common, human cases are rare. Alveolar echinococcosis (Echinococcus multilocularis) poses a much greater health threat to humans than cystic echinococcosis (Echinococcus granulosus), causing parasitic tumors that can form in your liver, lungs, brain, and other organs. If left untreated, alveolar echinococcosis can be fatal. Because the Echinococcus multilocularis cysts are slow-growing, infection with alveolar echinococcosis may not produce any symptoms for many years. Pain or discomfort in your upper abdominal region, weakness, and weight loss may occur as a result of the growing cysts. Alveolar echinococcosis (Echinococcus multilocularis) symptoms may mimic those of liver cancer and cirrhosis of the liver.

People who accidentally swallow the eggs of the Echinococcus multilocularis tapeworm are at risk for alveolar echinococcosis (Echinococcus multilocularis) infection. People at high risk of alveolar echinococcosis (Echinococcus multilocularis) are people in contact with the definitive hosts (mainly wild carnivores, for example foxes, coyotes, wolves) such as hunters, trappers, veterinarians, or others who have contact with wild foxes, or coyotes, or their stool, or household dogs and cats that have the opportunity to eat wild rodents infected with alveolar echinococcosis (Echinococcus multilocularis).

Humans can be exposed to Echinococcus multilocularis eggs by “hand-to-mouth” transfer or contamination.

By directly ingesting food items contaminated with stool from foxes or coyotes. This might include grass, herbs, greens, or berries gathered from fields.
By petting or handling household dogs or cats infected with the Echinococcus multilocularis tapeworm. These pets may shed the tapeworm eggs in their stool, and their fur may be contaminated. Some dogs “scent roll” in foreign material (such as wild animal feces) and may become contaminated this way.

The primary infection of alveolar echinococcosis (Echinococcus multilocularis) is in your liver, usually the right lobe, but direct extension to nearby organs, as well as spread via blood to your lungs and brain is common. Alveolar echinococcosis (Echinococcus multilocularis) is inhibited by the host from completing its development and remains in the proliferative stage indefinitely. The larval mass resembles a cancer in appearance and behavior. In chronic alveolar hydatid infections, the lesion consists of a central necrotic cavity filled with a white amorphous material that is covered with a thin peripheral layer of dense fibrous tissue. Host tissue is directly invaded by extension of the budding and proliferating cyst wall, causing a pressure necrosis of surrounding host tissue. A vigorous inflammatory and fibrous tissue reaction usually surrounds the larval mass. Diagnosis is often delayed until an advanced and inoperable stage; mortality rates have traditionally been high, ranging between 50% and 75%.

See your doctor if you think you may have alveolar echinococcosis (Echinococcus multilocularis). Diagnosis of alveolar echinococcosis (Echinococcus multilocularis) can be made by a blood test that looks for the presence of antibodies to Echinococcus multilocularis.

Echinococcosis life cycle

Echinococcosis life cycle life cycle involves two animals. A carnivore is the definitive host – where the adult worms live in the intestines – and almost any mammal, including humans, can be the intermediate host – where the worms form cysts in various organs.

Echinococcosis also known as hydatid disease or 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, ⁷, ⁸, ⁹. Echinococcosis is a zoonosis, a disease that is transmitted to humans from animals. Six species of Echinococcus tapeworms (family Taeniidae) have been identified which infect a wide range of domestic and wild animals, but four are of human health concern: Echinococcus granulosus (which causes cystic echinococcosis), Echinococcus multilocularis (which causes alveolar echinococcosis), and two forms of neotropical echinococcosis Echinococcus vogeli (which cause polycystic echinococcosis) and Echinococcus oligarthrus (which cause unicystic echinococcosis) ², ⁹. Two new species have recently been identified: Echinococcus shiquicus in small mammals from the Tibetan plateau and Echinococcus felidis in African lions, but their zoonotic (animal to human) transmission potential is unknown ². Several studies have shown that echinococcus infections are an increasing public health concern and that they can be regarded as emerging or re-emerging diseases.

Neotropical Echinococcosis (Echinococcus vogeli and Echinococcus oligarthrus) follow the same life cycle although with differences in hosts, morphology, and cyst structure. Adults of Echinococcus vogeli reach up to 5.6 mm long, and Echinococcus oligarthrus up to 2.9 mm. Neotropical Echinococcosis (Echinococcus vogeli and Echinococcus oligarthrus) cysts are generally similar to those found in cystic echinocccosis but are multi-chambered.

A number of herbivorous and omnivorous animals act as intermediate hosts of Echinococcus. They become infected by ingesting the Echinococcus eggs in contaminated food and water, and the parasite then develops into larval stages in the organs of definitive host (e.g., foxes, coyotes, and dogs). Carnivores act as definitive hosts for the parasite, and harbour the mature tapeworm in their intestine. The definitive hosts are infected through the consumption of organs of intermediate hosts (e.g., sheeps, cattle, goats, pigs and rodentts) that contain the parasite larvae.

Humans act as so-called accidental intermediate hosts in the sense that humans acquire infection in the same way as other intermediate hosts, but are not involved in transmitting the infection to the definitive host (e.g., foxes, coyotes, and dogs).

Several distinct genotypes of Echinococcus granulosus are recognized, some having distinct intermediate host preferences. Some genotypes are considered species distinct from Echinococcus granulosus. Not all Echinococcus granulosus genotypes cause infections in humans. The Echinococcus granulosus genotype causing the great majority of cystic echinococcosis infections in humans is principally maintained in a dog–sheep–dog cycle, yet several other domestic animals may also be involved, including goats, swine, cattle, camels and yaks.

Alveolar echinococcosis usually occurs in a wildlife cycle between foxes or other carnivores with small mammals (mostly rodents) acting as intermediate hosts. Domesticated dogs and cats can also act as definitive hosts.

Cystic Echinococcosis Life Cycle

The adult Echinococcus granulosus sensu lato (2mm to 7 mm long) resides in the small intestine of the definitive host (number 1). Gravid proglottids release eggs (number 2) that are passed in the feces, and are immediately infectious. After ingestion by a suitable intermediate host, 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 aberrant intermediate hosts, and become infected by ingesting eggs (number 2). Oncospheres are released in the intestine (number 3), and hydatid cysts develop in a variety of organs (number 4). If cysts rupture, the liberated protoscolices may create secondary cysts in other sites within the body (secondary echinococcosis).

Figure 4. Cystic Echinococcosis Life Cycle (Echinococcus granulosus sensu lato life cycle)

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Alveolar Echinococcosis Life Cycle

The adult Echinococcus multilocularis (1.2—4.5 mm long) (number 1) resides in the small intestine of the definitive host. Gravid proglottids release eggs (number 2) that are passed in the feces, and are immediately infectious. After ingestion by a suitable intermediate host, eggs hatch in the small intestine and releases a six-hooked oncosphere (number 3) that penetrates the intestinal wall and migrates through the circulatory system into various organs (primarily the liver for Echinococcus multilocularis). The oncosphere develops into a multi-chambered (“multilocular”), thin-walled (alveolar) hydatid cyst (number 4) that proliferates by successive outward budding. Numerous protoscolices develop within these cysts. 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 aberrant intermediate hosts, and become infected by ingesting eggs (number 2). Oncospheres (number 3) are released in the intestine and cysts develop within in the liver (number 4). Metastasis or dissemination to other organs (e.g., lungs, brain, heart, bone) may occur if protoscolices are released from cysts, sometimes called “secondary echinococcosis”.

Figure 5. Alveolar Echinococcosis Life Cycle (Echinococcus multilocularis life cycle)

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Echinococcosis Geographic Distribution

Cystic echinococcosis (Echinococcus granulosus sensu lato) occurs worldwide (except Antarctica) and more frequently in rural, grazing areas where dogs ingest organs from infected animals. 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).

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. 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.

Alveolar echinococcosis (Echinococcus multilocularis) is confined to the northern hemisphere, including central and northern Europe, Central Asia, regions of China, northern Russia, northern Japan, north-central United States, northwestern Alaska, and northwestern Canada. In North America, Echinococcus multilocularis (alveolar echinococcosis) is found primarily in the north-central region as well as Alaska and Canada. Rare human cases have been reported in Alaska, the province of Manitoba, and Minnesota. Only a single indigenous inhabitant case in the United States (Minnesota) has been confirmed.

Neotropical Echinococcosis (Echinococcus vogeli and Echinococcus oligarthrus) occur in Central and South America.

Echinococcosis Hosts

Cystic echinococcosis (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).

For alveolar echinococcosis (Echinococcus multilocularis), foxes, particularly red foxes (Vulpes vulpes), are the primary definitive host species. Other canids including domestic dogs, wolves, and raccoon dogs (Nyctereutes procyonoides) are also competent definitive hosts. Many rodents can serve as intermediate hosts, but members of the subfamily Arvicolinae (voles, lemmings, and related rodents) are the most typical.

The natural definitive host of Echinococcus vogeli is the bush dog (Speothos venaticus), and possibly domestic dogs. Pacas (Cuniculus paca) and agoutis (Dasyprocta spp.) are known intermediate hosts. Echinococcus oligarthrus uses wild neotropical felids (e.g. ocelots, puma, jaguarundi) as definitive hosts, and a broader variety of rodents and lagomorphs as intermediate hosts.

Echinococcosis Prevention

You can help prevent cystic echinococcosis (Echinococcus granulosus) by limiting areas where your dogs are allowed and don’t let your animals eat meat infected with Echinococcus granulosus cysts. To prevent alveolar echinococcosis (Echinococcus multilocularis), limit contact with wild animals like foxes, coyotes, and dogs, and limit your dog’s contact with rodents.

Cystic echinocccosis prevention

Cystic echinococcosis (Echinococcus granulosus) or hydatid disease is controlled by preventing transmission of the Echinococcus granulosus parasitic tapeworms. Prevention measures include limiting the areas where dogs are allowed and preventing animals from consuming 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.

Alveolar echinococcosis prevention

Alveolar echinococcosis (Echinococcus multilocularis) can be prevented by avoiding contact with wild animals such as foxes, coyotes, and dogs and their fecal matter and by limiting the interactions between dogs and rodent populations.

If you live in an area where Echinococcus multilocularis (alveolar echinococcosis) is found in rodents and wild canines, take the following precautions to avoid infection:

Don’t touch a fox, coyote, stray dogs or other wild canine, dead or alive, unless you are wearing gloves. Hunters and trappers should use plastic gloves to avoid exposure.
Don’t keep wild animals, especially wild canines, as pets or encourage them to come close to your home.
Don’t allow your dogs and cats to wander freely or to capture and eat rodents.
Do not allow dogs to feed on rodents and other wild animals.
If you think that your pet may have eaten rodents, consult your veterinarian about possible preventive treatments.
Wash your hands with soap and warm water after handling dogs or cats, and before handling food.
Teach children the importance of washing hands to prevent infection.
Do not collect or eat wild fruits or vegetables picked directly from the ground. All wild-picked foods should be washed carefully or cooked before eating.

Echinococcosis signs and symptoms

Echinococcosis signs and symptoms depend on which Echinococcus tapeworms you’ve been infected with: Echinococcus granulosus (which causes cystic echinococcosis), Echinococcus multilocularis (which causes alveolar echinococcosis), and Echinococcus vogeli (which cause polycystic echinococcosis) and Echinococcus oligarthrus (which cause unicystic echinococcosis).

Echinococcosis is relatively common in the liver (∼70%) and lung (∼20–30%) but rarely affects the spine (∼0.2–1%) ¹⁸.

Cystic Echinococcosis signs and symptoms

People with cystic echinococcosis (Echinococcus granulosus) or hydatid disease often remain asymptomatic for 10 years or more until the hydatid cysts containing the larval parasites grow large enough to cause discomfort, pain, nausea, and vomiting.

As cystic echinococcosis (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

Echinococcus granulosus (cystic echinococcosis) cysts grow over the course of several years before reaching maturity and the rate at which symptoms appear typically depends on the location of the Echinococcus granulosus cyst. The Echinococcus granulosus cysts are mainly found in your liver and lungs, but can also appear in your spleen, kidneys, heart, bone, and central nervous system, including your brain and eyes. Liver and lung signs/symptoms are the most common clinical manifestations, as these are the most common sites for cysts to develop. In addition to the liver and lungs, other organs (spleen, kidneys, heart, bone, and central nervous system, including the brain and eyes) can also be involved with resulting symptoms.

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.

Alveolar echinococcosis signs and symptoms

Alveolar echinococcosis (Echinococcus multilocularis) is characterized by slow growing, destructive parasitic tumor in your liver that may spread to other organs including your lungs and brain. In humans, the larval forms of Echinococcus multilocularis do not fully mature into cysts but cause vesicles that invade and destroy surrounding tissues and causing abdominal pain and biliary obstruction, weight loss, and malaise being the only manifestations evident in early infection. This may be misdiagnosed as liver cancer. Rarely, alveolar echinococcosis (Echinococcus multilocularis) can cause liver failure and death because of the spread into nearby tissues (e.g., lungs, spleen) and, rarely, your brain. Alveolar echinococcosis (Echinococcus multilocularis) is a dangerous disease that can result in a mortality rate of between 50% and 75%, especially because most affected people live in remote locations and have limited access to health care.

Polycystic echinococcosis signs and symptoms

Echinococcus vogeli affects mainly the liver, where it acts as a slow growing tumor; secondary cystic development is common. Too few cases of Echinococcus oligarthrus have been reported for characterization of its clinical presentation.

Echinococcosis complications

Rupture of echinococcosis cyst, whether spontaneous or traumatic, can cause site-specific complications. Ruptured or leaking cysts can release protoscolices into the peritoneum, causing secondary hydatidosis ¹⁹. Rupture of liver cysts into the biliary tree can result in biliary obstruction, superinfection of the cyst, and secondary peritonitis, while rupture of the lung cysts into the bronchial tree can result in pneumonitis, pneumothorax, pleural effusion, and secondary pleuritis ²⁰, ²¹.

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 ²².

Echinococcosis diagnosis

The diagnosis of echinococcosis varies depending on the infecting Echinococcus species. The primary infection of alveolar echinococcosis (Echinococcus multilocularis) is in the liver, usually the right lobe. The liver is the most common site of hydatid cysts, followed by the lungs, in patients with cystic echinococcosis (Echinococcus granulosus).

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 ¹⁴, ²³. 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 ²⁴, ²⁵, ²⁶, ²⁷. The sequence of cyst changes during the natural history is still unclear ²⁸. Liver cysts appear to grow at a lower rate than lung cysts ²⁹. Clinical symptoms usually occur when the cyst compresses or ruptures into neighbouring structures.

Cystic Echinococcosis diagnosis

The diagnosis of Echinococcus granulosus infection or cystic echinococcosis 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. Cystic echinococcosis (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 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).

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.

Alveolar Echinococcosis diagnosis

Alveolar echinococcosis or Echinococcus multilocularis infection closely mimics liver cancer or cirrhosis and is more commonly diagnosed in people of an advanced age. Plain radiographs show hepatomegaly and characteristic scattered areas of radiolucency outlined by calcific rings 2 to 4 mm in diameter. The usual CT image of E. multilocularis infection is that of indistinct solid tumors with central necrotic areas and perinecrotic plaque-like calcifications. Serologic test results are usually positive at high titers. Comparing a patient’s titers with both purified-specific and shared antigens permits the serologic discrimination between patients infected with Echinococcus multilocularis and those infected with Echinococcus granulosus.

Antibody Detection

Immunodiagnostic tests can be very helpful in the diagnosis of echinococcosis, particularly in conjunction with imaging, and should be used before invasive methods. However, the clinician must have some knowledge of the characteristics of the available tests and the patient and parasite factors in order to interpret assay results. False-positive reactions may occur in persons with other tapeworm (cestode) infections, some other helminth infections, cancer, and liver cirrhosis. Negative test results do not rule out echinococcosis because some cyst carriers do not have detectable antibodies. Whether the patient has detectable antibodies depends on the physical location, integrity, and vitality of the larval cyst.

Sensitivity of serum antibody detection using indirect hemagglutination, 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 ³⁰, ³¹, ³². 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.

Confirmatory tests must be used (arc-5 test; Antigen B (AgB) 8 kDa/12 kDa subunits or EgAgB8/1 immunoblotting) in dubious cases ³⁰, ³¹. Immunoblotting may be used as a first-line test and is best for differential diagnosis ³³. Mass screening in populations at risk optimally deploys ultrasound and serology ³⁴.

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 ³⁵.

Cystic echinococcosis (Echinococcus granulosus)

Indirect hemagglutination (IHA), indirect fluorescent antibody (IFA) tests, and enzyme immunoassays (EIA) are sensitive tests for detecting antibodies in serum of patients with cystic echinococcosis (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.

Alveolar echinococcosis (Echinococcus multilocularis)

Polycystic echinococcosis (Echinococcus vogeli)

Echinococcosis ultrasound classification

For hepatic echinococcosis, 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) ³⁶:

CE 1: unilocular fluid collection/simple cyst with double line sign.
CE 2: multivesicular/multiseptated cyst. “honeycomb” or “rosette-like”.
CE 3A: a fluid collection with a detached membrane (water lily sign).
CE 3B: the presence of daughter cysts in a solid matrix.
CE 4: cysts with a heterogeneous hypoechoic/hyperechoic matrix without daughter cysts.
CE 5: solid cystic wall.
CL: “cystic lesion” stage (undifferentiated)

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 ³⁷.

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 ³⁸.

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) ³⁹.

Figure 6. World Health Organization echinococcosis ultrasound classification

WHO echinococcosis ultrasound classification

[Source ³⁶ ]

Echinococcosis differential diagnosis

Echinococcosis can mimic a large number of conditions, depending on the site of the cyst.

Liver echinococcosis differential diagnoses include:

Liver abscess
Liver cysts
Budd-Chiari syndrome
Biliary colic
Biliary cirrhosis
Tuberculosis
Primary hepatic carcinoma

A detailed history and physical exam, alongside proper workup including serology and imaging, is key in making the diagnosis and ruling out diseases that may mimic hydatidosis.

Echinococcosis treatment

Echinococcosis treatment varies depending on the infecting Echinococcus species. Treatment options for cystic echinococcosis (Echinococcus granulosus) include antiparasitic drugs (albendazole or mebendazole), cyst puncture, and PAIR (Puncture, Aspiration, Injection of protoscolecide, Reaspiration). In some cases, no treatment but a conservative “watch and wait” approach is best.

Alveolar echinococcosis (Echinococcus multilocularis) requires antiparasitic drug with or without surgery.

Cystic echinococcosis treatment

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 ⁴⁰.

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.

World Health Organization (WHO) guidelines for cystic echinococcosis treatment

World Health Organization (WHO) 2025 guidelines for cystic echinococcosis treatment ⁴¹, ⁴²:

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 ³⁹. 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 ⁴³. 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 ³⁹. 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 ⁴⁴, 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 ³⁹. 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 ⁴⁴, 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 ³⁹. 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 ³⁹. 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 ⁴³. 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 ³⁹. 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 ³⁹. 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 ⁴⁵. 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 ³⁹. 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 ⁴¹, ⁴².

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.

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.

Alveolar echinococcosis treatment

Follow-up after surgical treatment

Follow-up after surgical treatment is best performed by MRI of the chest ⁶. This can be done without contrast enhancement and requires heavily T2-weighted sequences. This technique has the highest sensitivity to detect postoperative recurrence very early (small fluid filled cysts). Its biggest disadvantage being lack of availability and affordability in most cystic echinococcosis endemic regions of the world.

Computed tomography of the chest is a less sensitive alternative and implies radiation exposure. Patients should be followed for at least 5 years after surgery. In patients with remaining cysts, long-term follow-up is needed.

Echinococcosis prognosis

Echinococcosis 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 cystic echinococcosis (Echinococcus granulosus) make a full recovery and the Echinococcosis has high rates of morbidity and mortality ⁴⁶. Recurrence at the site of the cyst or in other sites occurs in some cases ⁴⁷, ⁴⁸, ⁴⁹, ⁵⁰. Recurrence rates for those with spinal cystic echinococcosis at 24 months was 48% ⁴⁶. It is for this reason that close follow-up with serial imaging is required.

Rinaldi F, Brunetti E, Neumayr A, Maestri M, Goblirsch S, Tamarozzi F. Cystic echinococcosis of the liver: A primer for hepatologists. World J Hepatol. 2014 May 27;6(5):293-305. doi: 10.4254/wjh.v6.i5.293.[↩][↩]
Moro P, Schantz PM. Echinococcosis: a review. Int J Infect Dis. 2009 Mar;13(2):125-33. https://doi.org/10.1016/j.ijid.2008.03.037[↩][↩][↩][↩][↩][↩]
Vuitton DA, McManus DP, Rogan MT, Romig T, Gottstein B, Naidich A, Tuxun T, Wen H, Menezes da Silva A; World Association of Echinococcosis. International consensus on terminology to be used in the field of echinococcoses. Parasite. 2020;27:41. doi: 10.1051/parasite/2020024[↩][↩][↩][↩]
Wen H, Vuitton L, Tuxun T, Li J, Vuitton DA, Zhang W, McManus DP. Echinococcosis: Advances in the 21st Century. Clin Microbiol Rev. 2019 Feb 13;32(2):e00075-18. doi: 10.1128/CMR.00075-18[↩][↩][↩][↩][↩][↩]
Autier B, Gottstein B, Millon L, Ramharter M, Gruener B, Bresson-Hadni S, Dion S, Robert-Gangneux F. Alveolar echinococcosis in immunocompromised hosts. Clin Microbiol Infect. 2023 May;29(5):593-599. https://www.clinicalmicrobiologyandinfection.org/article/S1198-743X(22)00630-9/fulltext[↩]
Weber TF, Junghanss T, Stojković M. Pulmonary cystic echinococcosis. Curr Opin Infect Dis. 2023 Oct 1;36(5):318-325. doi: 10.1097/QCO.0000000000000962[↩][↩][↩]
Pal, Mahendra & Alemu, Habtamu & Megersa, Lencho & Garedo, Derartu & Bodena, Ebisa. (2022). Cystic Echincoccoosis: A Comprehensive Review on Life Cycle, Epidemiology, Pathogenesis, Clinical Spectrum, Diagnosis, Public Health and Economic Implications, Treatment, and Control. International Journal of Clinical and Experimental Medicine Research. 6. 10.26855/ijcemr.2022.04.005. https://www.researchgate.net/publication/359576923_Cystic_Echincoccoosis_A_Comprehensive_Review_on_Life_Cycle_Epidemiology_Pathogenesis_Clinical_Spectrum_Diagnosis_Public_Health_and_Economic_Implications_Treatment_and_Control[↩][↩][↩]
About Echinococcosis. https://www.cdc.gov/echinococcosis/about[↩][↩]
Echinococcosis. https://www.who.int/news-room/fact-sheets/detail/echinococcosis[↩][↩][↩][↩]
Almulhim AM, John S. Echinococcus Granulosus. [Updated 2023 Aug 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539751[↩][↩]
Ghasemirad H, Bazargan N, Shahesmaeili A, Harandi MF. Echinococcosis in immunocompromised patients: A systematic review. Acta Trop. 2022 Aug;232:106490. doi: 10.1016/j.actatropica.2022.106490[↩]
Monge-Maillo B, Lopez-Velez R. Cystic echinococcosis of the bone. Curr Opin Infect Dis. 2023 Oct 1;36(5):341-347. doi: 10.1097/QCO.0000000000000951[↩]
Bresson-Hadni S, Spahr L, Chappuis F. Hepatic Alveolar Echinococcosis. Semin Liver Dis. 2021 Aug;41(3):393-408. doi: 10.1055/s-0041-1730925[↩][↩][↩][↩]
Echinococcosis Laboratory Diagnsosi. https://www.cdc.gov/dpdx/echinococcosis/index.html#tabs-1-2[↩][↩][↩][↩]
Jensenius M, Mørch K, Yaqub S, Halvorsen DS, Reims HM, Björk IG, Røsok BI, Oltmanns G, Helbak K, Øines Ø, Lier T. Alveolar echinococcosis. Tidsskr Nor Laegeforen. 2024 Sep 9;144(10). https://tidsskriftet.no/en/2024/09/clinical-review/alveolar-echinococcosis[↩][↩]
Kern P, Menezes da Silva A, Akhan O, Müllhaupt B, Vizcaychipi KA, Budke C, Vuitton DA. The Echinococcoses: Diagnosis, Clinical Management and Burden of Disease. Adv Parasitol. 2017;96:259-369. doi: 10.1016/bs.apar.2016.09.006[↩]
Echinococcosis. https://www.cdc.gov/dpdx/echinococcosis/index.html[↩][↩]
Sioutis S, Reppas L, Bekos A, Soulioti E, Saranteas T, Koulalis D, Sapkas G, Mavrogenis AF. Echinococcosis of the spine. EFORT Open Rev. 2021 Apr 1;6(4):288-296. doi: 10.1302/2058-5241.6.200130[↩]
Symeonidis N, Pavlidis T, Baltatzis M, Ballas K, Psarras K, Marakis G, Sakantamis A. Complicated liver echinococcosis: 30 years of experience from an endemic area. Scand J Surg. 2013;102(3):171-7. doi: 10.1177/1457496913491877[↩]
McManus DP, Zhang W, Li J, Bartley PB. Echinococcosis. Lancet. 2003 Oct 18;362(9392):1295-304. doi: 10.1016/S0140-6736(03)14573-4[↩]
Moro P, Schantz PM. Echinococcosis: a review. Int J Infect Dis. 2009 Mar;13(2):125-33. doi: 10.1016/j.ijid.2008.03.037[↩]
Langer JC, Rose DB, Keystone JS, Taylor BR, Langer B. Diagnosis and management of hydatid disease of the liver. A 15-year North American experience. Ann Surg. 1984 Apr;199(4):412-7. https://pmc.ncbi.nlm.nih.gov/articles/instance/1353359/pdf/annsurg00122-0050.pdf[↩]
Hosch W, Junghanss T, Stojkovic M, Brunetti E, Heye T, Kauffmann GW, Hull WE. Metabolic viability assessment of cystic echinococcosis using high-field 1H MRS of cyst contents. NMR Biomed. 2008 Aug;21(7):734-54. doi: 10.1002/nbm.1252[↩]
Romig T, Zeyhle E, Macpherson CN, Rees PH, Were JB. Cyst growth and spontaneous cure in hydatid disease. Lancet. 1986 Apr 12;1(8485):861. doi: 10.1016/s0140-6736(86)90974-8[↩]
Frider B, Larrieu E, Odriozola M. Long-term outcome of asymptomatic liver hydatidosis. J Hepatol. 1999 Feb;30(2):228-31. doi: 10.1016/s0168-8278(99)80066-x[↩]
Wang Y, He T, Wen X, Li T, Waili A, Zhang W, Xu X, Vuitton DA, Rogan MT, Wen H, Craig PS. Post-survey follow-up for human cystic echinococcosis in northwest China. Acta Trop. 2006 Apr;98(1):43-51. doi: 10.1016/j.actatropica.2006.01.009[↩]
Müfit K, Nejat I, Mercan S, Ibrahim K, Mete UY, Yüksel K. Growth of multiple hydatid cysts evaluated by computed tomography. J Clin Neurosci. 1998 Apr;5(2):215-7. doi: 10.1016/s0967-5868(98)90042-x[↩]
Rogan MT, Hai WY, Richardson R, Zeyhle E, Craig PS. Hydatid cysts: does every picture tell a story? Trends Parasitol. 2006 Sep;22(9):431-8. doi: 10.1016/j.pt.2006.07.003[↩]
Larrieu EJ, Frider B. Human cystic echinococcosis: contributions to the natural history of the disease. Ann Trop Med Parasitol. 2001 Oct;95(7):679-87. doi: 10.1080/00034980120094730[↩]
Siracusano A, Bruschi F. Cystic echinococcosis: progress and limits in epidemiology and immunodiagnosis. Parassitologia. 2006 Jun;48(1-2):65-6.[↩][↩]
Ito A, Craig PS. Immunodiagnostic and molecular approaches for the detection of taeniid cestode infections. Trends Parasitol. 2003 Sep;19(9):377-81. doi: 10.1016/s1471-4922(03)00200-9[↩][↩]
Siles-Lucas MM, Gottstein BB. Molecular tools for the diagnosis of cystic and alveolar echinococcosis. Trop Med Int Health. 2001 Jun;6(6):463-75. doi: 10.1046/j.1365-3156.2001.00732.x[↩]
Akisu C, Delibas SB, Bicmen C, Ozkoc S, Aksoy U, Turgay N. Comparative evaluation of western blotting in hepatic and pulmonary cystic echinococcosis. Parasite. 2006 Dec;13(4):321-6. doi: 10.1051/parasite/2006134321[↩]
Macpherson CN, Milner R. Performance characteristics and quality control of community based ultrasound surveys for cystic and alveolar echinococcosis. Acta Trop. 2003 Feb;85(2):203-9. doi: 10.1016/s0001-706x(02)00224-3[↩]
Khabiri AR, Bagheri F, Assmar M, Siavashi MR. Analysis of specific IgE and IgG subclass antibodies for diagnosis of Echinococcus granulosus. Parasite Immunol. 2006 Aug;28(8):357-62. doi: 10.1111/j.1365-3024.2006.00837.x[↩]
WHO Informal Working Group. Expert consensus for the diagnosis and treatment of cystic and alveolar echinococcosis in humans. International classification of ultrasound images in cystic echinococcosis for application in clinical and field epidemiological settings. Acta Trop. 2010 Apr;114(1):1-16. https://doi.org/10.1016/j.actatropica.2009.11.001[↩][↩]
Beggs I. The radiology of hydatid disease. AJR Am J Roentgenol. 1985 Sep;145(3):639-48. doi: 10.2214/ajr.145.3.639[↩]
Stojkovic M, Rosenberger K, Kauczor HU, Junghanss T, Hosch W. Diagnosing and staging of cystic echinococcosis: how do CT and MRI perform in comparison to ultrasound? PLoS Negl Trop Dis. 2012;6(10):e1880. doi: 10.1371/journal.pntd.0001880[↩]
Brunetti E, Kern P, Vuitton DA; Writing Panel for the WHO-IWGE. Expert consensus for the diagnosis and treatment of cystic and alveolar echinococcosis in humans. Acta Trop. 2010 Apr;114(1):1-16. doi: 10.1016/j.actatropica.2009.11.001[↩][↩][↩][↩][↩][↩][↩][↩][↩]
Bygott JM, Chiodini PL. Praziquantel: neglected drug? Ineffective treatment? Or therapeutic choice in cystic hydatid disease? Acta Trop. 2009 Aug;111(2):95-101. doi: 10.1016/j.actatropica.2009.04.006[↩]
WHO guidelines for the treatment of patients with cystic echinococcosis. Geneva: World Health Organization; 2025. Licence: CC BY-NC-SA 3.0 IGO https://iris.who.int/server/api/core/bitstreams/9f8adf1f-7f84-4d05-a13a-9c1adb503020/content[↩][↩]
WHO guidelines for the treatment of patients with cystic echinococcosis [Internet]. Geneva: World Health Organization; 2025. Executive summary. Available from: https://www.ncbi.nlm.nih.gov/books/NBK616284[↩][↩]
Kern P, Menezes da Silva A, Akhan O, Mullhaupt B, Vizcaychipi KA, Budke C, et al. The echinococcoses: diagnosis, clinical management and burden of disease. Adv Parasitol. 2017;96:259–369. doi: 10.1016/bs.apar.2016.09.006[↩][↩]
Akhan O, Yildiz AE, Akinci D, Yildiz BD, Ciftci T. Is the adjuvant albendazole treatment really needed with PAIR in the management of liver hydatid cysts? A prospective, randomized trial with short-term follow-up results. Cardiovasc Intervent Radiol. 2014;37(6):1568–74. doi: 10.1007/s00270-014-0840-2[↩][↩]
Cobo F, Yarnoz C, Sesma B, Fraile P, Aizcorbe M, Trujillo R, Diaz-de-Liaño A, Ciga MA. Albendazole plus praziquantel versus albendazole alone as a pre-operative treatment in intra-abdominal hydatisosis caused by Echinococcus granulosus. Trop Med Int Health. 1998 Jun;3(6):462-6. doi: 10.1046/j.1365-3156.1998.00257.x[↩]
Neumayr A, Tamarozzi F, Goblirsch S, Blum J, Brunetti E. Spinal cystic echinococcosis–a systematic analysis and review of the literature: part 2. Treatment, follow-up and outcome. PLoS Negl Trop Dis. 2013 Sep 19;7(9):e2458. doi: 10.1371/journal.pntd.0002458[↩][↩]
Mansfield BS, Pieton K, Pather S. Spinal Cystic Echinococcosis. Am J Trop Med Hyg. 2019 Jan;100(1):9-10. doi: 10.4269/ajtmh.18-0588[↩]
Sayek I, Tirnaksiz MB, Dogan R. Cystic hydatid disease: current trends in diagnosis and management. Surg Today. 2004;34(12):987-96. doi: 10.1007/s00595-004-2830-5[↩]
Dhar P, Chaudhary A, Desai R, Agarwal A, Sachdev A. Current trends in the diagnosis and management of cystic hydatid disease of the liver. J Commun Dis. 1996 Dec;28(4):221-30.[↩]
Bouraoui H, Trimeche B, Mahdhaoui A, Majdoub A, Zaaraoui J, Hajri Ernez S, Gouider J, Ammar H. Echinococcosis of the heart: clinical and echocardiographic features in 12 patients. Acta Cardiol. 2005 Feb;60(1):39-41. doi: 10.2143/AC.60.1.2005047[↩]