AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Hydatid disease is a parasitic infestation by a tapeworm of the genus Echinococcus. It is not endemic in the United States, but the change of immigration patterns and the improvement of 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.

Pathophysiology

Human echinococcosis is a zoonotic infection caused by the tapeworm of the genus Echinococcus. Of the 4 known species of Echinococcus, 3 are of medical importance in humans. These are Echinococcus granulosus, causing cystic echinococcosis (CE); Echinococcus multilocularis, causing alveolar echinococcosis (AE); and Echinococcus vogeli. E granulosus is the most common of the three. E multilocularis is rare but is the most virulent, and E vogeli is the most rare.

Frequency

United States

Despite the rise in 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

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 5 are intensive endemic areas. The incidence of 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. Infestation with E vogeli is the most rare form of echinococcosis and is reported mainly in the southern parts of South America.

Mortality/Morbidity

• 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 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).

Race

• 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.

Sex

• No sexual predilection is recognized.

Age

• 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.
• AE is a disease of older adults, with an average age at diagnosis of older than 50 years.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

Many hydatid cysts remain asymptomatic, even into advanced age. 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 CE, symptoms can be produced by mass effect or cyst complications.
• • Symptoms due to pressure 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.
• • 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.
• • 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 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

Physical examination findings from 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 portal hypertension secondary to either biliary cirrhosis or obstruction of the inferior vena cava.
  • Urticaria and erythema may be seen.
• Vital signs
• • Fever could be a sign of secondary infection or 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.

Causes

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

• Their life cycle involves only 2 hosts, one definitive and the other intermediate. Humans act as an accidental intermediate host. The life cycle has 3 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.
• Two biological forms of E granulosus have been recognized (depending on the geographic location and type of intermediate host), (1) the northern type and (2) the European type.
• • 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 8 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 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.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Biliary cirrhosis

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab 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.
• • 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.

Imaging Studies

• Plain films
• • In 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 AE, results from plain films may be normal.
• Ultrasound
• • 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.
• CT scan
• • CT scan 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.
• MRI: Images show the cysts adequately, but MRI offers no real advantage over CT scan.

Other Tests

• 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.

Procedures

• Endoscopic retrograde cholangiopancreatography: It is both diagnostic and therapeutic in patients with intrabiliary rupture of a hydatid cyst, in whom sphincterotomy can be performed.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

Medical management differs for CE and 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, consider risks and benefits, indications, and contraindications for each case before making a decision regarding the type and timing of surgery.

• Chemotherapy in CE
• • 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.
  • Monitoring: Monitor patients for adverse effects of agents every 2 weeks with a 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 were 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
• • 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 monitoring are the same as with CE, but the length of treatment changes.
  • Outcome: A significant increase in 10-year survival rates exists in patients receiving chemotherapy compared to patients who are not (85-90% vs 10%, respectively).
• PAIR in CE: This technique, performed using either ultrasound or CT guidance, involves aspiration of the 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 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 is the 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.
• • Indications: Inoperable patients; patients refusing surgery; 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 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.
• • 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 CE and AE.

• Cystic echinococcosis
• • 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 for infected and communicating cysts are choices for surgical technique. The more radical the procedure, the lower the risk of relapses but the higher the risk of complications. Patient care must be individualized accordingly.
  • 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 severely damaged cysts with no viable protoscoleces. Further evaluation of this scolicidal agent is needed.
    • At surgery, the exact location of the cyst is identified and correlated to 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, omentum is needed to fill the cavity. In the case of hepatic cysts, the fluid is inspected for bile staining and 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 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
• • 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.
  • 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.

Consultations

Consultants are needed in different contexts to help in the management of CE and 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 PAIR procedure is needed.
• In certain instances involving AE, interventions are required to improve organ function.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

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.

Drug Category: Anthelmintics

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

Drug Name	Mebendazole (Vermox)
Description	Causes worm death by selectively and irreversibly blocking uptake of glucose and other nutrients in susceptible adult intestine where helminths dwell. Broad-spectrum synthetic anthelmintic. Metabolites are devoid of anthelmintic activity.
Adult Dose	40-50 mg/kg/d PO for 3-6 mo (primary mode of therapy) or for 4 d prior to surgery and then 1 mo postoperatively as adjunct
Pediatric Dose	<2 years: Not established >2 years: Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	Carbamazepine and phenytoin may decrease effects; cimetidine may increase levels
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Periodically evaluate hematopoietic and hepatic function during therapy because of reports of neutropenia and disturbed liver function with prolonged therapy; adjust dose in hepatic impairment; caution in first trimester of pregnancy

Drug Category: Trematodicides

Used to potentiate effect of benzimidazoles during therapy.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Inpatient Care

• 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 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.

Further Outpatient Care

• Outpatient care is directed towards the following end points:
• • Chemotherapy: Postoperative treatment with benzimidazoles is continued for 1 month in patients with CE who have undergone complete resection or PAIR successfully. The treatment is continued for 3-6 months for patients with resected 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 CBC count and liver enzyme evaluation performed at biweekly intervals for 3 months and then every 4 weeks to monitor for toxicity. ELISA or indirect hemagglutination tests are usually performed at 3-, 6-, 12-, and 24-month intervals as screening for recurrence of resected disease or aggravation of existing disease.
  • Imaging: Ultrasonography and/or CT scan are used in follow-up at the same intervals as the laboratory tests or as clinically indicated.

In/Out Patient Meds

• Antibiotics are used prophylactically for surgery as indicated in patients with a cystobiliary fistula, for treatment of infected cysts, and for 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

Deterrence/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

Complications

• All the usual complications related to the surgical procedure and anesthesia
• Related to the parasite
• • Recurrence
  • Metastasis
  • Infection
  • Spillage and seeding (secondary echinococcosis) - Allergic reaction or anaphylactic shock
• Related to the medical treatment
• • Hepatotoxicity
  • Anemia
  • Thrombocytopenia
  • Alopecia
  • Embryotoxicity
  • Teratogenicity
  • Spillage and seeding (secondary echinococcosis)
• Related to PAIR
• • Hemorrhage
  • Mechanical damage to other tissue
  • Infections
  • Allergic reaction or anaphylactic shock
  • Persistence of daughter cysts
  • Sudden intracystic decompression leading to biliary fistulas
• Related to scolicidal agents - Chemical sclerosing cholangitis

Prognosis

• Prognosis mainly depends on the type of infestation (ie, whether it is CE or AE).
• • In CE, prognosis is generally good, with complete cure with total surgical excision without spillage. Spillage occurs in 2-25% of cases (depends on location and surgeon's experience), and the operative mortality rate varies from 0.5-4% for the same reasons.
  • In AE, 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 10-year mortality rates from 94% to 10%.

Patient Education

• Education is aimed at teaching the population at risk about the disease, its methods of transmission, its hosts, and the methods of prevention (see Deterrence/Prevention).

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Medicolegal pitfalls lie mainly in misdiagnosis, lack of experience, and a hospital's lack of preparation.
• • In most cases, signs and symptoms from echinococcal infestation are nonspecific and can lead to an error in diagnosis. This usually results in an error in management and, sometimes, in catastrophic results in which major spillage occurs secondary to a poorly planned and executed percutaneous puncture or rupture during surgery.
  • Once the diagnosis is made, the surgeon's experience plays a large role in the outcome. Not only is experience with the infestation important, but also experience in the surgical procedure. This lack of experience adds up to an increase in mortality and morbidity rates related to spillage and incomplete resections.
  • The hospital where a patient is treated should be well equipped with the proper equipment and laboratory facilities and diagnostic and interventional radiology, pharmacy, and medical specialists. Deficiency in any of these should prompt transfer of the patient to an appropriate facility.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

• Elsebaie SB, El-Sebae MM, Esmat ME. Modified endocystectomy versus pericystectomy in echinococcus granulosus liver cysts: a randomized controlled study, and the role of specific anti-hydatid IgG4 in detection of early recurrence. J Egypt Soc Parasitol. Dec 2006;36(3):993-1006.
• Filippou D, Tselepis D, Filippou G. Advances in Liver Echinococcosis: Diagnosis and Treatment. Clin Gastroenterol Hepatol. Dec 5 2006.
• Flisser A. Larval cestodes. In: Collier L, Balows A, Sussman M, eds. Topley and Wilson's Microbiology and Microbial Infections. Parasitology. Vol 5. 9th ed. New York, NY: Oxford University Press; 1998:. 539-60.
• Gargouri M, Ben Amor N, Ben Chehida F, et al. Percutaneous treatment of hydatid cysts (Echinococcus granulosus). Cardiovasc Intervent Radiol. Jun-Jul 1990;13(3):169-73. [Medline].
• Heath DD. Immunology of echinococcus infections. In: Thompson R, Lymbery AJ, eds. Echinococcus and Hydatid Disease. Wallingford, Oxon: CAB International; 1995:. 183-200.
• Kjossev KT, Losanoff JE. Hydatid cysts of the liver: TN(R)C classification. Int Surg. Oct-Dec 1998;83(4):311-3. [Medline].
• Liu D, Lightowlers MW, Rickard MD. Evaluation of a monoclonal antibody-based competition ELISA for the diagnosis of human hydatidosis. Parasitology. Apr 1992;104 (Pt 2):357-61. [Medline].
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Article Last Updated: Feb 8, 2007