Hydatid Cysts 

Updated: May 07, 2019
Author: Imad S Dandan, MD; Chief Editor: BS Anand, MD 

Overview

Background

Hydatid disease is a parasitic infestation by a tapeworm of the genus Echinococcus.[1] It is not endemic in the United States, but the change in the immigration patterns and the marked increase in transcontinental transportation over the past 4 decades have caused a rise in the profile of this previously unusual disease throughout North America. This has led to the necessity for physicians to be more aware of its clinical features, diagnosis, and management.

Patient education is aimed at teaching the population at risk about the disease, its methods of transmission, its hosts, and the methods of prevention.

Pathophysiology

Human echinococcosis is a zoonotic infection caused by the tapeworm of the genus Echinococcus. Of the four known species of Echinococcus, three are of medical importance in humans. These are E granulosus, causing cystic echinococcosis (CE); E multilocularis, causing alveolar echinococcosis (AE); and E vogeli. E granulosus is the most common of the three; cDNA encoding calmodulin, a calcium sensor protein, (rEgCaM) may play an essential role in the biologic function of E granulosus as a calcium binding protein.[2]  E multilocularis is rare but is the most virulent, and E vogeli is the most rare.

Etiology

Echinococcosis is caused by larval cestodes of the phylum Platyhelminthes (tapeworms).

Their life cycle involves only two hosts, one definitive and the other intermediate. Humans act as an accidental intermediate host. The life cycle has three developmental stages, (1) the adult tapeworm in the definitive host, (2) eggs in the environment, and (3) the metacestode in the intermediate host. Metacestodes are ingested by the definitive host. The metacestodes mature into the tapeworm in the definitive host and, in turn, release eggs into the environment. The intermediate host ingests the eggs, which hatch into metacestodes, which infest the liver, lungs, muscles, and other organs of the intermediate host.[3]

Two biological forms of E granulosus have been recognized (depending on the geographic location and type of the intermediate host), (1) the northern type and (2) the European type, as follows:

  • The northern type is maintained in the tundra by a predator-prey relationship between the wolf and large deer, but dogs and coyotes can also become infested. Humans become infested in areas where reindeer are domesticated.

  • Intermediate hosts for the European type include camels, pigs, sheep, cattle, goats, horses, and many other animals. The definitive host for the European biotype is overwhelmingly the dog, but it also occurs in foxes, hyenas, and jackals. This is the most common biotype. The adult stage of E multilocularis occurs mainly in foxes and rarely in wolves, coyotes, lynxes, cats, and black bears.

The intermediate hosts for E multilocularis are eight families of rodents, including mice, rats, hamsters, gerbils, and squirrels.

E vogeli is a neotropical species maintained in the bush dog and the paca. It can easily infect other mammals that are exposed to its feces. It is the most rare form of the echinococci.

Exposure to food and water contaminated by the feces of an infected definitive host or poor hygiene in areas of infestation can lead to echinococcosis.

Epidemiology

United States data

Despite an increase in its occurrence, echinococcosis remains a very rare disease (< 1 case per 1 million inhabitants) in the continental United States. Northern Alaska has endemic areas of E granulosus, but the frequency of infection remains low (< 1 case per 100,000 inhabitants).

International data

Echinococcosis is also unusual in northern Europe. The endemic areas are the Mediterranean countries, the Middle East, the southern part of South America, Iceland, Australia, New Zealand, and southern parts of Africa; the latter five regions are intensive endemic areas. Central Asia, particularly China, is also an endemic area.[4, 5, 6]

The incidence of cystic echinococcosis (CE) in endemic areas ranges from 1-220 cases per 100,000 inhabitants, while the incidence of AE ranges from 0.03-1.2 cases per 100,000 inhabitants, making it a much more rare form of echinococcosis. An epidemiologic study of CE in Romania emphasized the need for improved preventive measures.[7] Infestation with E vogeli is the most rare form of echinococcosis and is reported mainly in the southern parts of South America.

Sex-, age-, and race-related demographics

No sexual predilection is recognized for hydatid cysts.

Because of the restricted geographic distribution of the echinococcal worms, persons of certain races are affected more commonly than others; however, the parasite has the capability of infecting persons of all races equally.

The cysts grow slowly, and a cyst is rarely diagnosed during childhood or adolescence unless the brain is affected. CE is a disease of younger adults, with an average age at diagnosis of 30-40 years, whereas alveolar echinococcosis (AE) is a disease of older adults, with an average age at diagnosis of older than 50 years.

Prognosis

Prognosis mainly depends on the type of infestation (ie, whether it is cystic [CE] or alveolar echinococcosis [AE]). In CE, the prognosis is generally good, and complete cure is possible with total surgical excision without spillage. Spillage occurs in 2%-25% of cases (depends on the location and surgeon's experience), and the operative mortality rate varies from 0.5%-4% for the same reasons.

In AE, the prognosis is much worse. Cure is only possible with early detection and complete surgical excision. In patients in whom the latter is not possible, the addition of long-term chemotherapy has decreased the 10-year mortality rates from 94% to 10%.

Morbidity/mortality/

Morbidity is usually secondary to free rupture of the echinococcal cyst (with or without anaphylaxis), infection of the cyst, or dysfunction of affected organs. Examples of dysfunction of affected organs are biliary obstruction, cirrhosis, bronchial obstruction, renal outflow obstruction, increased intracranial pressure secondary to a mass, and hydrocephalus secondary to cerebrospinal fluid outflow obstruction.

In CE, mortality is secondary to anaphylaxis, systemic complications of the cysts (eg, sepsis, cirrhosis, respiratory failure), or operative complications.

In clinical cases of AE, the mortality rate is 50%-60%. This figure reaches 100% for untreated or poorly treated AE. Sudden death has been reported with AE in asymptomatic patients (autopsy diagnosis).

Complications

All the usual complications related to the surgical procedure and anesthesia apply. Postoperative risk factors related to hepatic hydatidosis include age, previous surgery for hepatic hydatidosis, localization in the hepatic center, the presence of biliary communications, and cystic evolutionary complications.[8] However, radical surgery techniques seem to be protective factors.[8]

Complications related to the parasite include the following:

  • Recurrence

  • Metastasis

  • Infection

  • Spillage and seeding (secondary echinococcosis): Allergic reaction or anaphylactic shock

Those related to the medical treatment include the following:

  • Hepatotoxicity

  • Anemia

  • Thrombocytopenia

  • Alopecia

  • Embryotoxicity

  • Teratogenicity

  • Spillage and seeding (secondary echinococcosis)

Complications related to puncture, aspiration, injection, and reaspiration (PAIR) intervention include the following:

  • Hemorrhage

  • Mechanical damage to other tissues

  • Infections

  • Allergic reaction or anaphylactic shock

  • Persistence of daughter cysts

  • Sudden intracystic decompression leading to biliary fistulas

Those related to scolicidal agents includes chemical sclerosing cholangitis.

A rare case of alveolar echinococcosis embolism that required emergency surgical intervention has been reported.[1]

 

Presentation

History

Many hydatid cysts remain asymptomatic, even into advanced age. The parasite load, the site, and the size of the cysts determine the degree of symptoms. A history of living in or visiting an endemic area must be established. Also, exposure to the parasite through the ingestion of foods or water contaminated by the feces of a definitive host must be determined.

Theoretically, echinococcosis can involve any organ. The liver is the most common organ involved, followed by the lungs. These 2 organs account for 90% of cases of echinococcosis.

In cystic echinococcosis (CE), symptoms can be produced by a mass effect or cyst complications. Symptoms due to the pressure effect of the cyst usually take a long time to manifest, except when they occur in the brain or the eyes. Most symptomatic cysts are larger than 5 cm in diameter. Organs affected by E granulosus are the liver (63%), lungs (25%), muscles (5%), bones (3%), kidneys (2%), brain (1%), and spleen (1%).

Pressure effects are initially vague. They may include nonspecific pain, cough, low-grade fever, and the sensation of abdominal fullness. As the mass grows, the symptoms become more specific because the mass impinges on or obstructs specific organs. Note the following:

  • In the liver, the pressure effect of the cyst can produce symptoms of obstructive jaundice and abdominal pain. With biliary rupture, the classic triad of biliary colic, jaundice, and urticaria is observed. Passage of hydatid membranes in the emesis (hydatid emesia) and passage of membranes in the stools (hydatid enterica) may occur rarely.

  • Involvement of the lungs produces chronic cough, dyspnea, pleuritic chest pain, and hemoptysis. Expectoration of cyst membranes and fluid is observed with intrabronchial rupture.

  • Headache, dizziness, and a decreased level of consciousness may signify cerebral involvement. Specific neurologic deficits may occur depending on the location of the cyst in the brain.

Secondary complications may occur as a result of infection of the cyst or leakage of the cyst. Note the following:

  • Minor leaks lead to increased pain and a mild allergic reaction characterized by flushing and urticaria. Major rupture leads to a full-blown anaphylactic reaction, which is fatal if not treated promptly. A rupture into the biliary tree can lead to obstruction by the daughter cysts, producing cholangitis. Rupture into the bronchi can lead to expectoration of cyst fluid.

  • Infection of the cyst can occur either as a primary infection or as a secondary infection following an episode of a leak into the biliary tree, a cystobiliary fistula. Symptoms range from mild fever to full-blown sepsis.

  • Extremity pain with or without neurologic deficit is a sign of either bone or muscle involvement.

In alveolar echinococcosis (AE), the liver is the primary site of infection, and it closely mimics cirrhosis or carcinoma. Symptomatology is that of progressive liver dysfunction that ultimately leads to liver failure. The progression can occur over weeks, months, or years. Distant metastasis is possible, and involvement of other organs (eg, lung, brain, bone) can occur in as many as 13% of the patients.

Physical Examination

Physical examination findings in patients with echinococcosis are nonspecific. The findings are related to the effect of the cyst on the anatomy or the function of the affected organ(s) and to an acute allergic reaction.

Skin

Jaundice could be a sign of biliary obstruction. Spider angiomas are a sign of cirrhosis of the liver. Urticaria and erythema may be seen.

Vital signs

Fever could be a sign of primary or secondary infection or an allergic reaction. Hypotension is observed with anaphylaxis secondary to a cyst leak.

Lungs

Decreased breath sounds over the affected area are signs of airway obstruction with consolidation of the affected segment, lobule, lobe, or the whole lung.

Abdomen

The most common sign is abdominal tenderness. Hepatomegaly may be present or a mass may be felt. Tender hepatomegaly is a sign of secondary infection of the cyst, especially when coupled with fever and chills. Ascites is rare.

Splenomegaly can be the result of either splenic echinococcosis or portal hypertension.

Extremities

Bone involvement can result in tenderness over the affected area and, rarely, a palpable mass. Muscle involvement is usually characterized by a palpable mass. 

Peripheral nerve compression can occur, although extremely rarely. It results in nerve-specific sensory and/or motor deficit.

Brain

Findings from the neurologic examination are nonspecific and depend on the area of the brain involved. They range from very mild to full coma and cerebral herniation.

Eyes

Ocular involvement is rare. Abnormal findings from the ophthalmologic examination include decreased visual acuity, blindness, and exophthalmos.

 

DDx

 

Workup

Laboratory Studies

The results of routine laboratory blood work are nonspecific. Liver involvement may be reflected in an elevated bilirubin or alkaline phosphatase level. Leukocytosis may suggest infection of the cyst. Eosinophilia is present in 25% of all persons who are infected, while hypogammaglobinemia is present in 30%.

Almost every serodiagnostic technique has been evaluated for echinococcosis, with variable results. Note the following:

  • The indirect hemagglutination test and the enzyme-linked immunosorbent assay (ELISA) have a sensitivity of 80% overall (90% in hepatic echinococcosis, 40% in pulmonary echinococcosis) and are the initial screening tests of choice.

  • Immunodiffusion and immunoelectrophoresis demonstrate antibodies to antigen 5 and provide specific confirmation of reactivity.

  • The ELISA test is useful in follow-up to detect recurrence.

Casoni test

Historically, an intradermal skin test (Casoni test) was used and had a sensitivity of 70%. It is now largely abandoned because of its low sensitivity, low accuracy, and potential for severe local allergic reaction.

Imaging Studies

Plain films

In cystic echinococcosis (CE), findings from plain films of the chest, abdomen, or any other involved site are, at best, nonspecific and mostly nonrevealing. A thin rim of calcification delineating a cyst is suggestive of an echinococcal cyst.

In alveolar echinococcosis (AE), results from plain films may be normal.

Ultrasonography

Ultrasonography helps in the diagnosis of hydatid cysts when the daughter cysts and hydatid sand are demonstrated. The accuracy of ultrasound evaluations remains operator-dependent.

Computed tomography (CT) scanning

CT scanning has an accuracy of 98% and the sensitivity to demonstrate the daughter cysts. It is the best test for the differentiation of hydatid from amebic and pyogenic cysts in the liver.

In AE, the CT scan findings are sometimes indistinguishable from those of hepatocellular carcinoma.

Magnetic resonance imaging (MRI)

Images show the cysts adequately, but MRI offers no real advantage over CT scanning.

Procedures

Endoscopic retrograde cholangiopancreatography (ERCP)

ERCP is both diagnostic and therapeutic in patients with intrabiliary rupture of a hydatid cyst, in whom a sphincterotomy can be performed.

 

Treatment

Approach Considerations

Inpatient care for individuals who have had surgical resection of their hydatid cyst(s) is similar to that for any other surgical procedure on the affected organ.

Special consideration must be made for patients with hepatic cystic echinococcosis (CE) who were found to have biliary communication. These patients must be observed for signs and symptoms of either biliary obstruction or fistula formation. If either of these complications occurs, the patient must be treated by percutaneous or endoscopic stenting of the biliary tree with or without sphincteroplasty.

Postoperatively, treatment with benzimidazoles is continued for approximately 1 month, although the exact duration has not been determined.

Antibiotics are used prophylactically for surgery as indicated in patients with a cystobiliary fistula, for the treatment of infected cysts, and for the treatment of associated infections. Benzimidazoles are continued after discharge.

Transfer

Several criteria must be met in medical centers in order for patients to be treated appropriately. The lack of any of the following criteria should lead to patient transfer:

  • Medical staff experienced in the treatment of echinococcosis (eg, surgeons, radiologists, infectious disease consultants)

  • Medical centers that are able to provide the services for treatment (eg, well-equipped intensive care unit and surgical ward, well-equipped operating room, diagnostic radiology and laboratory facilities)

  • Availability of scolicidal agents

Medical Care

Medical management differs for cystic echinococcosis (CE) and alveolar echinococcosis (AE). In CE, surgery remains the primary treatment and the only hope for complete cure. Better forms of chemotherapy and newer methods, such as the puncture, aspiration, injection, and reaspiration (PAIR) technique are now available but need to be tested. Currently, indications for these modes of therapy are restricted. In AE, radical surgical excision is coupled with chemotherapy in operable cases and long-term aggressive chemotherapy for partially resected or unresectable lesions. In CE, one should consider the risks and benefits, indications, and contraindications for each case before making a decision regarding the type and timing of surgery.

Chemotherapy in CE

Note the following:

  • Indications: Chemotherapy is indicated in patients with primary liver or lung cysts that are inoperable (because of location or medical condition), patients with cysts in 2 or more organs, and peritoneal cysts.

  • Contraindications: Early pregnancy, bone marrow suppression, chronic hepatic disease, large cysts with the risk of rupture, and inactive or calcified cysts are contraindications. A relative contraindication is bone cysts because of the significantly decreased response.

  • Chemotherapeutic agents: Two benzimidazoles are used, albendazole and mebendazole. Albendazole is administered in several 1-month oral doses (10-15 mg/kg/d) separated by 14-day intervals. New data for continuous treatment are emerging from China. The optimal period of treatment ranges from 3-6 months, with no further increase in the incidence of adverse effects if this period is prolonged. Mebendazole is also administered for 3-6 months orally in dosages of 40-50 mg/kg/d. Limited data are available on the weekly use of praziquantel, an isoquinoline derivative, at a dose of 40 mg/kg/wk, especially in cases in which intraoperative spillage has occurred. Albendazole has been found ineffective in the treatment of primary liver cysts in patients who are surgical candidates.[9]

  • Monitoring: Monitor patients for adverse effects of agents every 2 weeks with a complete blood cell (CBC) count and liver enzyme evaluation for the first 3 months and then every 4 weeks. Monitoring albendazole and mebendazole serum levels is desirable, but few laboratories are capable of performing this measurement. Imaging studies are required for follow-up on the morphologic status of the cyst.

  • Outcome from medical treatment of CE: Response rates in 1000 treated patients showed that 30% had cyst disappearance (cure), 30%-50% had a decrease in the size of the cyst (improvement), and 20%-40% had no changes. Also, younger adults responded better than older adults.

Chemotherapy in AE

Note the following:

  • Indications: Chemotherapy with benzimidazoles is used perioperatively for approximately 2 years in patients in whom radical resection is feasible because of possible undetected residual parasite tissue. In patients who undergo a partial resection, patients who are inoperable, or patients who have had a liver transplant, long-term chemotherapy is required (3-10 y).

  • Contraindications: Because chemotherapy is the only treatment in certain cases, contraindications are limited to early pregnancy and severe leukopenia. Chemotherapeutic agents and patient monitoring are the same as with CE, but the length of treatment is different.

  • Outcome: A significant increase in 10-year survival rates exists in patients receiving chemotherapy compared to patients who are not treated (85%-90% vs 10%, respectively).

PAIR in CE

The PAIR technique is performed using either ultrasound or computed tomography (CT) guidance, involves aspiration of the cyst contents via a special cannula, followed by injection of a scolicidal agent for at least 15 minutes, and then reaspiration of the cystic contents. This is repeated until the return is clear. The cyst is then filled with isotonic sodium chloride solution. Perioperative treatment with a benzimidazole is mandatory (4 d prior to the procedure and for 1-3 mo after).

The PAIR technique can be performed on liver, bone, and kidney cysts but should not be performed on lung and brain cysts. The cysts should be larger than 5 cm in diameter and type I or II according to the Gharbi ultrasound classification of liver cysts (ie, type I is purely cystic; type II is purely cystic plus hydatid sand; type III has the membrane undulating in the cystic cavity; and type IV has peripheral or diffuse distribution of coarse echoes in a complex and heterogeneous mass). PAIR can be performed on type III cysts as long as it is not a honeycomb cyst.

Note the following:

  • Indications: Inoperable patients; patients refusing surgery; patients with multiple cysts in segment I, II, and III of the liver; and relapse after surgery or chemotherapy are indications for the PAIR technique.

  • Contraindications: Early pregnancy, lung and brain cysts, inaccessible cysts, superficially located cysts (risk of spillage), type II honeycomb cysts, type IV cysts, and cysts communicating with the biliary tree (risk of sclerosing cholangitis from the scolecoidal agent) are contraindications for the PAIR technique.

  • Outcome: The reduced cost and shorter hospital stay associated with PAIR compared to surgery make it desirable. The risk of spillage and anaphylaxis is considerable, especially in superficially located cysts, and transhepatic puncture is recommended. Sclerosing cholangitis (chemical) and biliary fistulas are other risks. Experience is still limited, but early reports are supportive of this technique if the indications are followed.

Interventional procedures in AE

Patients with AE require interventional procedures when radical complete resective surgery is not possible. Local complications may occur. These interfere with the function of the organ and may be alleviated by certain interventional procedures. These procedures can be performed endoscopically or under ultrasound or CT guidance. Dilatation, stenting, drainage of collections, and sclerosis of esophageal varices are some examples. Note the following:

  • Indications: These include hyperbilirubinemia, vena cava thrombosis, portal vein thrombosis, necrotic collections, and bleeding esophageal varices.

  • Contraindications: Postinterventional chemotherapy is not possible, and the risk of spreading the parasite is high.

Surgical Care

The indications and type of surgery are different for cystic echinococcosis (CE) and alveolar echinococcosis (AE).

Cystic echinococcosis

Note the following:

  • Indications: Large liver cysts with multiple daughter cysts; superficially located single liver cysts that may rupture (traumatically or spontaneously); liver cysts with biliary tree communication or pressure effects on vital organs or structures; infected cysts; and cysts in lungs, brain, kidneys, eyes, bones, and all other organs are indications for surgery.

  • Contraindications: General contraindications to surgical procedures (eg, extremes of age, pregnancy, severe preexisting medical conditions); multiple cysts in multiple organs; cysts that are difficult to access; dead cysts; calcified cysts; and very small cysts are contraindications.

  • Choice of surgical technique: Radical surgery (total pericystectomy or partial affected organ resection, if possible), conservative surgery (open cystectomy), or simple tube drainage of infected and communicating cysts for surgical options. The more radical the procedure, the lower the risk of relapses but the higher the risk of complications. Patient care must be individualized accordingly.

  • Laparoscopic approach has gained more acceptance and popularity in recent years.

Description of surgical procedure

The basic steps of the procedure are eradication of the parasite by mechanical removal, sterilization of the cyst cavity by injection of a scolicidal agent, and protection of the surrounding tissues and cavities.

Scolicidal agents include formalin, hydrogen peroxide, hypertonic saline, chlorhexidine, absolute alcohol, and cetrimide. A variety of complications have been described with all scolicidal agents, but in the authors' experience, 0.5% cetrimide solution provides the best protection with the least complications. Other scolicidal agents are 70%-95% ethanol and 15%-20% hypertonic saline solutions. A report by Ochieng'-Mitula and Burt in 1996 on the injection of ivermectin in the hydatid cysts of infected gerbils revealed several damaged cysts with no viable protoscoleces.[10] Further evaluation of this scolicidal agent is needed.

At surgery, the exact location of the cyst is identified and correlated with the radiologic findings. The surrounding tissues are protected by covering them with cetrimide-soaked pads. The cyst is then evacuated using a strong suction device, and cetrimide is injected into the cavity. This procedure is repeated until the return is completely clear. Cetrimide is instilled and allowed to sit for 10 minutes, after which it is evacuated, and the cavity is irrigated with isotonic sodium chloride solution. This ensures both mechanical and chemical evacuation and destruction of all cyst contents. During this process, care is taken to ensure no spillage occurs to prevent seeding and secondary infestation.

The cavity is then filled with isotonic sodium chloride solution and closed. Rarely, the omentum is needed to fill the cavity. The cyst fluid is inspected for bile staining at the end of the evacuation and irrigation process. The inside of the cyst is inspected, and any bile duct communication is sutured. In case of infected cysts with biliary communication, closed suction drainage is required. Regardless of whether an open or a laparoscopic approach is chosen, these basic principles must be followed in order to ensure the safety of the procedure.

Medical requirements

The medical staff at the treating center should have experience with treating CE. Concomitant treatment with benzimidazoles (albendazole or mebendazole) has been reported to reduce the risk of secondary echinococcosis. Treatment is started 4 days preoperatively and lasts for 1 month.

Alveolar echinococcosis

Note the following:

  • Indications: The indication is resectability of the liver lesion (assessed by imaging techniques preoperatively).

  • Contraindications: These are inoperable lesions, extensive lesions, and lesions extending outside the liver and involving other organs.

  • Choice of surgical technique: Radical surgery with complete excision of the lesion is the only chance for cure. In certain cases, total hepatectomy with transplantation has been performed as long as no extra hepatic disease is present. Reemergence of the parasite in the transplanted liver and distant metastasis occur under immunosuppression. Partial resections of unresectable masses are considered to decrease the parasite load to aid the chemotherapeutic agents.[11] More recently, ex vivo liver resection combined with autotransplantation appears to show potential for curing end-stage hepatic alveolar echininococcosis in those with unresectable lesions.[12]

  • Medical requirements: Surgical staff experienced in major liver resections and medical staff experienced in the administration of chemotherapy to persons with AE are required. Perform liver transplantations in centers where a well-coordinated and experienced team is available.

Treatment comparison

A retrospective study showed laparoscopic therapy and puncture, aspiration, injection, and reaspiration (PAIR) intervention to be safe and effective alternative options to open surgery in patients with a suitable indication such as cyst type and location.[13]

Consultations

Consultants are needed in different contexts to help in the management of cystic echinococcosis (CE) and alveolar echinococcosis (AE).

Although an infectious disease consultant is needed to help in the administration and monitoring of chemotherapeutic agents, the interventional radiologist has different roles in CE and AE.

In certain cases of CE, the puncture, aspiration, injection, and reaspiration (PAIR) procedure is needed. In certain instances involving AE, interventions are required to improve organ function.

Prevention

Because human infection with Echinococcus results from fecal-oral contamination, prevention requires the following steps:

  • Education on proper hygiene

  • Proper cleansing of uncooked food and avoidance when possible

  • Dietary regulation of pet dogs (stop the habit of feeding viscera of intermediate hosts, such as sheep, to pet dogs)

  • Regulate pet dog activity to prevent ingestion of sheep material

  • Avoidance of unregulated dogs

  • Treatment of pet dogs in endemic areas for intestinal echinococcosis with praziquantel (5 mg/kg) periodically

  • Control of the dog population

  • Regulation of livestock butchering

Long-Term Monitoring

Outpatient care is directed towards the following end points:

  • Chemotherapy: Postoperative treatment with benzimidazoles is continued for 1 month in patients with cystic echinococcosis (CE) who have successfully undergone complete resection or puncture, aspiration, injection, and reaspiration (PAIR). The treatment is continued for 3-6 months for patients with resected alveolar echinococcosis (AE), incompletely resected CE, spillage during surgery or PAIR, and metastatic lesions. Chemotherapy is needed for 3-10 years for patients with partially resected AE, unresectable AE, or liver transplant for AE.

  • Laboratory tests: Patients on benzimidazoles should have a complete blood cell (CBC) count and liver enzyme evaluation performed at biweekly intervals for 3 months and then every 4 weeks to monitor for toxicity. Enzyme-linked immunosorbent assay (ELISA) or indirect hemagglutination tests are usually performed at 3-, 6-, 12-, and 24-month intervals to assess for recurrence of resected disease or aggravation of an existing disease.

  • Imaging: Ultrasonography and/or computed tomography (CT) scanning are used in follow-up at the same intervals as the laboratory tests or as clinically indicated.

 

Medication

Medication Summary

Drug therapy for echinococcosis is limited. The anthelmintic benzimidazoles, namely albendazole and mebendazole, are used for treatment and prophylaxis. Praziquantel, an isoquinoline derivative, is used as an adjunct for therapy.

Anthelmintics

Class Summary

Treatment of Echinococcus infestation as a primary modality or adjunct to surgery.

Albendazole (Albenza)

Decreases ATP production in the worm, causing energy depletion, immobilization, and, finally, death. Orally administered broad-spectrum anthelmintic with poor aqueous solubility. Poorly absorbed from the GI tract but metabolized quickly to albendazole sulfoxide, which is easily absorbed. Systemic activity is attributed to the first metabolite. Plasma level is noted to rise significantly (as much as 5-fold) when ingested after a high-fat meal. Experience in patients age < 6 y is limited.

Mebendazole (Vermox)

Causes worm death by selectively and irreversibly blocking the uptake of glucose and other nutrients in susceptible adult intestine where helminths dwell. Broad-spectrum synthetic anthelmintic. Metabolites are devoid of anthelmintic activity.

Trematodicides

Class Summary

Used to potentiate the effect of benzimidazoles during therapy.

Praziquantel (Biltricide)

Increases cell membrane permeability in susceptible worms, resulting in loss of intracellular calcium, massive contractions, and paralysis of musculature. In addition, produces vacuolization and disintegration of schistosome tegument. This is followed by the attachment of phagocytes to the parasite and death. Isoquinoline derivative that is easily absorbed through the GI tract.

 

Questions & Answers

Overview

What is a hydatid disease (echinococcosis)?

Which species cause hydatid disease (echinococcosis)?

What causes hydatid disease (echinococcosis)?

What is the prevalence of hydatid disease (echinococcosis) in the US?

What is the global prevalence of hydatid disease (echinococcosis)?

Which patient groups are at highest risk for hydatid disease (echinococcosis)?

What is the prognosis of hydatid disease (echinococcosis)?

What is the morbidity and mortality associated with hydatid disease (echinococcosis)?

What are the complications of hydatid disease (echinococcosis)?

Presentation

Which organs are affected by hydatid cysts?

What are the pressure effect symptoms of hydatid cysts?

What are the signs and symptoms of infection or leakage of hydatid cysts?

What are the signs and symptoms of alveolar echinococcosis (AE)?

What are physical findings suggestive of hydatid disease (echinococcosis)?

What are the dermatologic findings suggestive of hydatid cysts?

Which vital sign findings suggest hydatid cysts?

Which pulmonary findings suggest hydatid cysts?

Which abdominal findings suggest hydatid cysts?

Which musculoskeletal findings suggest hydatid cysts?

Which CNS findings suggest hydatid cysts?

Which ocular findings suggest hydatid cysts?

DDX

What are the differential diagnoses for Hydatid Cysts?

Workup

What is the role of lab studies in the diagnosis of hydatid cysts?

What is the role of the Casoni test in the diagnosis of hydatid cysts?

What is the role of radiography in the diagnosis of hydatid disease (echinococcosis)?

What is the role of ultrasonography in the diagnosis of hydatid cysts?

What is the role of CT scanning in the diagnosis of hydatid cysts?

What is the role of MRI in the diagnosis of hydatid cysts?

What is the role of endoscopic retrograde cholangiopancreatography (ERCP) in the diagnosis and management of hydatid cysts?

Treatment

What is the inpatient care for hydatid cysts?

When should patients with hydatid cysts be transferred for treatment?

What are the medical treatment options for hydatid disease (echinococcosis)?

What is the role of chemotherapy in the treatment of cystic echinococcosis (CE)?

What is the role of chemotherapy in the treatment of alveolar echinococcosis (AE)?

What is the role of the puncture, aspiration, injection, and reaspiration (PAIR) technique in the treatment of cystic echinococcosis (CE)?

Which interventional procedures are used in the treatment of alveolar echinococcosis (AE)?

What is the role of surgery in the treatment of cystic echinococcosis (CE)?

What is the role of surgery in the treatment of alveolar echinococcosis (AE)?

How is surgery performed for the treatment of cystic echinococcosis (CE)?

What is the role of benzimidazoles in the treatment of cystic echinococcosis (CE)?

What are effective alternative options for open surgery in the treatment of hydatid disease (echinococcosis)?

Which specialist consultations are needed for the management of hydatid disease (echinococcosis)?

How is hydatid disease (echinococcosis) prevented?

What is included in long-monitoring for hydatid disease (echinococcosis)?

Medications

Which medications are used for hydatid cysts?

Which medications in the drug class Trematodicides are used in the treatment of Hydatid Cysts?

Which medications in the drug class Anthelmintics are used in the treatment of Hydatid Cysts?