Perspective Chapter: Echinococcosis – An Updated Review

Abstract

Common Name: Dog Tapeworm. Echinococcus granulosus is most prevalent and causes cystic hydatid disease. Echinococcus multilocularis is uncommon and responsible for alveolar hydatid disease. Hydatid disease is a significant health problem worldwide. It is a zoonosis. Adult worm lives in the small intestine of dog and rarely wolf and fox. Dog is the optimal definitive host. The larval stage (hydatid cyst) is found in herbivorous animal like sheep, goat, cattle. Man is the accidental intermediate host. Echinococcal infection occurs through ingestion of eggs that are passed through the feces of definitive host. After ingestion of eggs, the egg liberates embryo which passes through the intestinal mucosa in the portal circulation. Right lobe of the liver is the commonest site for liver hydatid cyst. The cyst wall consists of pericyst, ectocyst and endocyst. Endocyst or the germinal layer is the site of asexual reproduction giving rise to brood capsule and scolices. Symptoms mainly due to pressure effect. Rarely fatal anaphylaxis may occur due to spontaneous rupture or during surgery. USG and CT is the most valuable imaging technique. Serology is an adjunct to diagnosis. Classification of hydatid cyst by Gharvi et al. into five types based on sonographic analysis. Treatment modalities include chemotherapy, percutaneous treatment and surgery.

1. Introduction

Echinococcosis or hydatid disease caused by canine tapeworm Echinococcus granulosus and rarely by Echinococcus multilocularis. It is a significant health and socio-economic problem globally and more than 1 million people are affected at any one time. Although hydatid cyst is a benign disease but treatment is difficult, recurrence rate is high and may cause life threatening complication. This chapter reflects updated review of evaluation, diagnosis and treatment of Echinococcosis.

Human Echinococcosis (Echinococcal cyst, Hydatidosis, Hydatid disease) is a parasitic disease caused by the tapeworm of the genus Echinococcus and the family Taeniidae. Hydatid disease has been described by Hippocrates who speaks of “Liver full of water.” The word echinococcus is Greek origin means “hedgehog berry.” Hydatid is also of Greek origin meaning a “water vesicle.” In Latin hydatid means a “drop of water.”

The genus Echinococcus contains four species:

1. Echinococcus granulosus.

2. Echinococcus multilocularis.

3. Echinococcus vogeli.

4. Echinococcus oligarthus.

E. granulosus is most common and causes cystic hydatid disease [1]. E. multilocularis is uncommon and causes alveolar hydatid disease. Echinococcus vogeli and oligarthus are rare entity and causes polycystic hydatid disease. Adult E. granulosus was described by Hartmann in the small intestine of dog in 1695 and the larval form (hydatid cyst) was recognized by Goeze in 1782.

Human Cystic Echinococcosis (CE) is a zoonosis and is prevalent in most parts of the world except Antarctica. It is most common in sheep and cattle raising areas of Australia, Africa, South America. It is also prevalent in Europe, China and Middle East. In endemic areas it is significant health and socio-economic problem. More than 1 million people are affected with Echinococcosis at any one time.

2. Habitat

Adult worm lives in the small intestine of dog and other canine carnivora like wolf and fox. The larval stage is found in sheep and other herbivorous animal like goat, cattle and horse. Human being is an accidental intermediate host.

3. Parasitology

Adult worm is a small tapeworm 3–6 mm in length and consists of scolex, a short neck and a strobila. The scolex is pyriform with four suckers and a prominent rostellum. Neck is short. The strobila is composed of three proglottides: (a) anterior immature, (b) middle mature (c) posterior gravid segment. The gravid proglottid contains about 200 and 800 ova. Adult worm survives 6–30 months.

4. Eggs

Ovoid in shape and brown in color. It contains an embryo which is called an oncosphere or hexacanth because it has six hooklets.

5. Larval form

Larval form develops into hydatid cyst in the various organs of intermediate host. It represents the structure of scolex of adult worm and remain invaginated within a vesicular body. After entering the definitive host the scolex with suckers and rostellar hooklets becomes exvaginated and mature into adult worm.

6. Lifecycle

Lifecycle is completed in two hosts.

6.1 Definitive host

Dog (The optimal host), wolf, jackal, fox.

6.2 Intermediate host

Sheep and cattle. Sheep is the ideal intermediate host. Man is the accidental intermediate host (dead end) and become infected when they accidentally ingest the eggs of the tapeworm during intimate handling of infected dogs or by consumption of vegetables, food and water contaminated with eggs.

Several distinct genotypes of E. granulosus are recognized but not all genotype causes human infection. The genotype causing CE in human is principally maintained in dog-sheep-dog cycle.

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

After ingestion of eggs hexacanth embryo hatch in the duodenum and penetrate the mucosa reaching into portal circulation and gets trapped in hepatic sinusoids and eventually develops into liver hydatid cyst (75%) which acts as a first filter.

Some embryo may pass through the liver and enters the right side of the heart and are caught in pulmonary circulation which acts as a second filter forming lung hydatid cyst (20%).

Few enters the systemic circulation and give rise to hydatid cyst of various other organ like spleen, kidney, eye, brain, bones [2].

Infection with echinococcal organism is the most common cause of liver cyst in the world [3].

7. Formation of hydatid cyst

Once the embryo is deposited in an organ it develops into a cyst filled with fluid. It enlarges slowly and reach a diameter of 0.5–1 cm in about 6 months. Mature cyst is able to survive within organs for years. The growing cyst evokes host tissue response with formation of fibrous capsule around it. Mature cyst has two layers:

1. Outer layer (Pericyst): It is a dense fibrous tissue layer and usually due to host response to the parasite. It is not present in pulmonary and brain hydatid cyst. Pericyst consists of two different layers. The inner layer of pericyst or exocyst is the result of an inflammatory and granulomatous reaction. It frequently contains osteopontin which regulates macrophage accumulation and calcium deposition. The outer layer is the adventitia and composed of biliovascular elements and tributaries of hepatic veins. Separating the exocyst from the adventitial layer is the basis of sub adventitial cystectomy.

2. Inner layer: It is further divided into two layers:

   1. Ectocyst: It is composed of acellular, chitinous, laminated hyaline material. It is efficient barrier for bacteria and an ultra-filter for protein.

   2. Endocyst: It is the inner germinal layer which is cellular and consists of number of nuclei within a protoplasmic mass and is very thin (22–25 μm). It is the vital layer of the cyst and responsible for production of hydatid fluid, ectocyst, brood capsule, scolices, and daughter cyst. From the inner wall of brood capsule protoscolices (new larva) develops which represents the head of the potential worm with invaginated scolex. Development of brood capsule from germinal layer indicates complete biologic development of cyst which occurs after 6 months of growth.

      Several thousands of protoscolices develop into mature hydatid cyst and thus it reflects a process of asexual reproduction.

      Daughter cyst formation is a defense mechanism. Any injury to hydatid cyst may cause daughter cyst formation. Daughter cysts are replica of mother cyst but without a pericyst. Even grand daughter cyst may develop. In uncomplicated cases the cyst cavity is filled with a sterile colorless antigenic fluid containing salt, enzymes, proteins and toxic sustances [4]. The formation of daughter cyst is called endogenic vesiculation. Exogenic vesiculation occurs when a small rupture or defect in the laminated membrane occurs and the germinal layer passes through it and creates a satellite hydatid cyst. This process is uncommon in E. granulosus but characteristic of larval stages of E. multilocularis. In E. multilocularis process of exogenic vesiculation is fulminant. Multiple vesicles are formed in all directions. The infected parenchyma has a multilocular appearance and centre becomes necrotic and spongy and filled with gelatinous fluid similar to that of mucoid liver carcinoma. Hepatic insufficiency is common and disease is often lethal [4].

8. Acephalocysts

Some cysts are sterile and may never produce brood capsule and some brood capsule may not produce scolices. These are called acephalocysts.

9. Clinical features

The clinical features of hydatidosis depend on the site, size, number, viability and stage of development of cyst [4]. Most of the time it is asymptomatic and incidentally discovered. Lung cyst gives rise to symptoms even if small. Liver cyst usually becomes symptomatic when it is more than 5 cm.

9.1 Clinical features of liver hydatid cyst

The symptoms can be non-specific or due to mass effect or cyst complications.

Symptoms	Signs
Right upper quadrant pain (74%)	Palpable mass in right upper quadrant (55%)
Vomiting	Fever
Dyspepsia	Jaundice
Non-specific fatigue	Malnutrition
Weight loss	Cholangitis
Fever	Pleural effusion
History of jaundice	Splenomegaly
Allergy	Ascites
Hydatid emesis	Skin rash
Hydatid enterica	Pancreatitis
	Hydatid cachexia (children in endemic areas)
	Hydatid thrill (if the cyst is present near lower margin of liver)

10. Clinical features of lung hydatid cyst

Cough, hemoptysis, chest pain, pneumothorax, dyspnoea.

11. Clinical features of H.C in other sites

Cerebral hydatid cyst may present with focal epilepsy.

Bone- Laminated layer is not well developed. The parasite migrate along the bony canal and erode the bone tissue. Erosion of bone may lead to pathological fracture.

12. Course of the disease

The hydatid cyst enlarges slowly and the growth rate depends on the immunological relationship between the parasite and the human and the resistance offered by surrounding tissues. Rate of growth is usually 1 mm in diameter per month. Sometimes the hydatid cyst dies, the germinal layer disintegrated and the hydatid fluid is absorbed. Over time the pericyst calcifies [5]. However, not every calcified cyst is dead.

13. Complications related to hydatid cyst

1. Infection and suppuration: Most frequent cause of infection is cysto biliary communication (CBC). The clinical presentation is similar to a pyogenic liver abscess.

2. Mass- effect: In CNS and lung small cyst causes serious symptoms. In liver large cyst may give rise to pressure atrophy of surrounding hepatocytes and compensatory hypertrophy of remaining liver tissue. Large cyst can replace entire liver lobe. Portal hypertension and Budd-Chiari like syndrome have been described.

3. Rupture:

   1. Internal: Injury or bile leak can damage the laminated membrane and liberated protoscolices occupy the space within the pericyst cavity. A univesicular cyst converted into multivesicular cyst.

   2. Free rupture:

      • Intraperitoneal: The hydatid cyst is a high-pressure cyst (30–70 cm of water). Because of high intracystic pressure, both univesicular and multivesicular cyst can rupture. Sudden rupture may give rise to acute abdomen with severe anaphylactic reaction and circulatory collapse. Cyst rupture also leads to release of thousands of protoscolices leading to disseminated abdominal hydatidosis.

      • Intrathoracic: can give rise to pleural effusion, empyema, pneumonitis, lung abscess. Rupture into a bronchiole may give rise to appearance of cyst in sputum. Rarely there is formation of broncho biliary fistula.

      • Intra biliary: Rupture into the biliary tree can lead to obstruction by the daughter cyst producing cholangitis, obstructive jaundice and sometime pancreatitis. Leak into the biliary tree can lead to classical triad of biliary colic, jaundice and urticaria. Hydatid emesis and hydatid enterica may occur rarely.

        CBC can be of minor communication and major communication. Major communication has a fistula diameter of more than 5 mm.

        Reported incidence of rupture of hydatid cyst into bile duct ranges from 2.6 to 30%. If the cyst content is bile stained a meticulous search for CBC is necessary.

      • Rupture into adjacent viscera: Rupture into digestive tract giving rise to hydatid emesis and in urinary tract hydatiduria.

        Rupture of hydatid cyst into Aorta, IVC and Heart with embolism have been reported.

14. Diagnosis

14.1 Imaging

1. Plain X-Ray: It is of limited value. Plain x-ray of the abdomen and chest may reveal elevation of right hemi diaphragm or a thin rim of calcification.

2. Ultrasound: It is the most common investigation used for the diagnosis of hydatid cyst and reported sensitivity of USG is 100% [6]. A cyst containing daughter cyst and hydatid sand are highly suggestive (Figure 1). A solitary anechoic liver cyst should be considered hydatid until proved otherwise.

US diagnostic features of hydatid cyst are:

1. multivesicular cyst has been termed as “cart wheel sign.”

2. Daughter cyst gives rise to “rosette appearance.”

3. separation of laminated membrane produces a split wall appearance and complete collapse resulting in “water lily sign.”

4. calcification of cyst wall.

Ultrasound also shows morphology of the cyst, thickness of the wall, extent of communication to biliary tree, the diameter of biliary and vascular channel. Supplemented with Doppler it indicates the status of portal vein, hepatic artery, and retro hepatic venacava. Intra-operative US (IOUS) is very helpful during surgery and can alter operative strategy.

Based on US sign Hassan Gharbi in 1981 classified the liver hydatid cyst into five types [7]. This classification is widely used:

Type I: Pure fluid collection.

Type II: Fluid collection with split wall.

Type III: Fluid collection with septa.

Type IV: Heterogenous appearance.

Type V: Those with reflecting thick wall.

Depending on the cyst characteristic described by Gharbi the WHO—IWGE proposed a new classification based on ultrasound morphology and corelated with activity of the disease that facilitate selection of treatment modalities.

WHO-IWGE classification of hydatid cyst [8]:

CL	Active	USG features—sign not pathognomonic, unilocular, no cyst wall
CE1	Active	Cyst wall, “hydatid sand,” rosette Like.
CE2	Active	Multivesicular, cyst wall, rosette Like.
CE3	Transitional	Detachment of laminated Membrane, water lily sign, Less round - decreased intra cystic pressure.
CE4	Inactive	Heterogenous hypo or hyper Echogenic degenerative contents, No daughter cyst.
CE5	Inactive	Thick calcified wall, calcification Partial or complete - not pathognomonic. But highly suggestive of diagnosis

1. c. CT: CT gives rise to more precise information regarding the number, position and cyst characteristics. It is more useful when complications are suspected (Figures 2 and 3). CT has high sensitivity and specificity. Discontinuity of cyst wall near bile ducts is highly suggestive of CBC. Calcification of cyst wall is easily seen on CT. Mother cyst containing daughter cyst are diagnostic of hydatid cyst. CT is also superior in detecting exogenous vesiculation. It also provides information regarding the position and extent of intra-abdominal disease. It is also a very useful investigation in suspected lung or brain hydatid cyst. CT is imperative for operative management specially with a laparoscopic approach (Figure 4) [9].

2. d. MRI: MRI gives rise to excellent image of liver and abdominal hydatidosis. It is most valuable diagnostic tool for skeletal and vertebral disease and cardiac cyst. MR Angiography can be done when large cysts are in close relation to a major vessel. An increase in signal intensity of the cyst content on MR suggest CBC or superinfection [10]. MRCP is considered the investigation of choice for jaundice patients with liver hydatid.

3. e. ERCP: Routine use of ERCP advocated by some authority to completely delineate bile duct anatomy and to visualize any clinically silent CBC [11]. Pre-operative endoscopic papillotomy is indicated:

   1. Imaging showing suspected hydatid material in CBD.

   2. Presenting feature is cholangitis whether CBC is present or not.

Figure 1.

USG of liver hydatid cyst.

Figure 2.

Adrenal hydatid cyst CT.

Indication of Post-operative endoscopic papillotomy:

1. Hydatid debris in CBD.

2. Biliary fistula lasting more than 3 weeks.

3. High output biliary fistula (more than 1 liter in 24 hours).

4. Presence of jaundice.

5. Short stricture involving papilla

14.2 Serology

A number of antibodies to the hydatid antigen produced from oncosphere, laminated membrane and cyst fluid. The detection of circulating Echinococcus granulosus antigen is less sensitive than the detection of antibodies. Detection of serum antibodies using specific antigen (8 and 16 KDA) from hydatid fluid are frequently used to support the diagnosis of CE.

14.3 Antibody detection

Test detecting antibody against antigen B are ELISA, Indirect hemagglutination test and indirect immunofluorescence test.

Test detecting antibody against hydatid fluid fraction 5 antigen are CFT and precipitation test. The arc of precipitation (Arc 5) seen on immune electrophoresis is most specific and virtually diagnostic of hydatid disease.

A negative serology does not exclude the diagnosis of hydatid disease in a anechoic liver cyst because of high incidence of false negative result (Figure 3).

Figure 3.

CT of liver hydatid cyst.

15. Clinical criteria for diagnosis

According to the WHO-IWGE the diagnostic criteria are:

1. Slowly growing cystic mass or masses diagnosed by imaging

2. Incidental finding of a cyst in a asymptomatic carrier or detected by screening technique

3. Anaphylactic reaction due to leaking or ruptured cyst.

The diagnosis is based on:

1. Typical organ lesion detected by imaging

2. High sensitivity and specificity serologic test

3. Macroscopic morphology of hydatid cyst in surgical specimen

4. Histopathology or parasitology typical for hydatid cyst

15.1 Treatment modalities

• Wait and see

• Chemotherapy

• Percutaneous treatment

• Surgery

Based on WHO Classification certain management guidelines suggested:

1. Active cyst: Type CL, CE1, CE2- About one- third of the cyst are sterile. In these patients management options are: wait and see, further differential diagnosis, chemotherapy.

   Remaining two-third of the patients having fertile cysts and half of them will have secondary cyst. Management options are: surgery, PAIR, chemotherapy.

2. In Transitional state (Type CE3): Living protoscolices can exist and all treatment options should be considered.

3. Inactive cysts (Type CE4 and CE5): Further differential diagnosis is usually necessary and no treatment is usually required.

15.2 Chemotherapy

It is an integral part of management of hydatid cyst. The main advantage of chemotherapy is that it can be given in out-patient basis and avoid surgical complications. The most commonly used agents are - mebendazole (MBZ) and albendazole (ABZ). Both drugs interfere with glucose absorption through the wall of the parasite leading to glycogen depletion. ABZ is the only drug that is ovicidal, larvicidal, and vermicidal and it is the drug of choice. Praziquantel has been used with albendazole to increase the protoscolicidal effect of albendazole but side effects are significant.

Chemotherapy can be given alone as a primary therapy, pre-interventional administration, or adjuvant therapy after operation.

15.3 Indications of primary chemotherapy

1. Contraindications to surgery

2. Poor surgical risk

3. Inoperable patient with primary liver and lung disease

4. Patient with multiple cyst in two or more organ

5. Multiple small liver cysts

6. Deep seated liver cyst

7. Prevention and management of secondary echinococcosis

8. Recurrent echinococcosis

9. In combination with surgery and PAIR

10. Pulmonary hydatid cyst

Available evidence indicates that chemotherapy alone is not the ideal treatment with high failure rate and recurrence. About 25% of the cyst recurs once medical therapy stopped [12]. Pre-operative chemotherapy is given to sterilize the cyst contents and thereby diminishing the chance of secondary echinococcosis by accidental spillage during surgery. Three to 4 weeks of pre- operative treatment significantly reduce viability of the cyst [13].

Short-course albendazole is ineffective [14]. Post-operative ABZ to be started for about 4 weeks if there is leakage of cyst contents during surgery. According to WHO-IWGE preinterventional administration of ABZ or MBZ should be given 4 days before intervention and continued one month for ABZ and 3 months for MBZ.

15.4 Dosage

ABZ is given orally 10–15 mg/kg/day in divided doses with a fat rich meal for 28 days followed by a gap of 14 days. Three such cycles to be given. Improvement is defined as reduction in cyst size more than 25%, membrane separation or calcification. Now there are emerging evidence that continuous treatment as opposed to gap in between the courses is safe and more effective. Limited data available for use of praziquantel. The dose is 40 mg/kg/week for the management of intraperitoneal spillage during surgery or other interventional procedure. In endemic areas echinococcosis can be prevented by administering Praziquantel to infected dogs. MBZ is given at a dosage of 40–50 mg/kg/day in three divided doses with a fat rich meal for a period of 3–6 months.

15.5 Side effects

Alteration of liver function has been reported. 10 to 20% patients may develop elevation of transaminases which is reversible. Idiopathic bone marrow suppression is also seen with these drugs. Other side effects are jaundice, pyrexia, alopecia and leucopenia.

15.6 Percutaneous treatment

PAIR (Puncture, Aspiration, Injection, Re-aspiration): Previously percutaneous puncture of hydatid cyst was contraindicated for fear of spillage around puncture site as pressure inside the cyst maybe as high 70 cm of water. A new interventional procedure- PAIR emerged in 1990 with high success rate. RCT by Khuru et al. in 1993 [15] and many other studies showed risk of anaphylaxis and risk of recurrence is negligible. The technique is ideal for Gharbi Type I to III cysts. Treatment of ABZ started 10 days before the procedure and continued for 1–2 months after the procedure.

16. Indication of pair

1. Cyst Type CL, CE1, CE3 and some CF2 (Gharbi Type I and II and some patients with Type III and IV with drainable material).

2. Infected cyst

3. Inoperable patient

4. Pregnant women

5. Patient with multiple cysts greater than 5 cm in diameter in different liver segments

6. Recurrence following surgery

7. Lack of response to chemotherapy

17. Contraindications to pair

1. TYPE III and IV cysts (Hydatid cyst with heterogenous echo pattern)

2. Communication with biliary system

3. Cysts inaccessible to puncture

4. Multiple septal divisions

5. Lung or bone cyst

6. Children less than 3 years old.

18. Technique

Classical PAIR procedure is done under USG guidance in the following steps:

1. Percutaneous puncture of the cyst through transhepatic route

2. Aspiration of cyst fluid and assessment for viable protoscolices and bilirubin

3. Injection of a scolicidal agent in the cyst and left for 15 minutes

4. Reaspiration and examination of fluid for viable protoscolices

5. Procedure is repeated until no viable protoscolices found or there is total separation of germinal layer from pericyst

6. A catheter can be left in cavity for drainage if it is more than 6 cm

Recurrence rate vary between 0 and 4% and overall complication rate vary between 15 to 40%. Major complications like anaphylactic shock is rare. Minor complications like urticaria, itching, hypotension, fever, infection, rupture into biliary system ranges from 10 to 30%. 2.8% patients require repeat procedure to achieve satisfactory result [16]. Complicated cysts, cysts with many daughter cysts or large volume cysts are indications of PAIR modification:

1. The PAIR catheterization technique

2. The D-PAI (Double puncture, aspiration and injection technique)

3. PEVAC (percutaneous evacuation of cyst content)

4. MOCAT (modified catheter aspiration technique)

19. Scolicidal agents

In any intervention on hydatid cysts major danger is spillage of viable protoscolices resulting in peritoneal dissemination. To kill the viable elements scolicidal agents are frequently injected into the cysts and also to cover the surrounding liver parenchyma with gauze or mops soaked in scolicidal agents.

Formalin, hypertonic saline 15–20%, chlorhexidine, cetrimide, hydrogen peroxide, polyvinyl pyrrolidone-iodine, silver nitrate, ethyl alcohol are some of the many agents used [17]. Formalin causes sclerosing cholangitis, Hypertonic saline can lead to hypernatremia, Acidosis with chlorhexidine and chemical cholangitis with alcohol has been reported. No agent should be injected pre-evacuation due to high intra cyst pressure. WHO regards use of scolicidal agents for intra operative killing of infectious material questionable because no agent is both safe and effective. According to WHO ethanol 70–95%, hypertonic saline 15–20% and cetrimide solution 0.5% having relatively low risk [18].

19.1 Surgery

Surgery remains the gold standard for hydatid cyst management. Objectives are:

1. Eradicate macroscopic parasite

2. Inactivate the scolices

3. Prevent spillage of cyst content

4. Elimination of all viable materials of the cyst

5. Management of CBC if present

6. Management of residual cavity

19.2 Indications of surgery

1. Large cyst with multiple daughter cysts

2. Superficially located cysts that may rupture

3. Infected cysts

4. Cysts with CBC

5. Large cysts exerting pressure effect on vital structure

6. Cysts in lung, brain, kidney, bones and other organs

19.3 Contraindications to surgery

1. Extreme of age

2. Pregnancy 1st and 3rd trimester

3. Severe comorbid conditions

4. Numerous cysts

5. Cysts in multiple organs

6. Difficult to access

7. Dead cysts

8. Very small cyst less than 5 cm

19.4 Surgical options

1. Conservative—open/laparoscopic—deroofing and cyst evacuation. It is a tissue sparing procedure which is limited to remove the parasites and other viable elements with most of the pericyst left in situ.

2. Radical surgery:

   1. Cysto pericystectomy

   2. Liver resection

   3. Liver transplantation

20. Conservative surgery

20.1 Basic steps

1. Adequate exposure of the cyst

2. Safe decompression of the cyst

3. Sterilization of the cyst contents

4. Evacuation of the cyst contents

5. Identification and management of CBC if present

6. Management of residual cavity.

21. Open technique

After adequate exposure, the cyst is packed off from rest of the peritoneal cavity using blue or green packs soaked in 15–20% saline (Figure 2). Colored packs and drapes ensure better visibility of whitish cyst element. The cyst is aspirated with 16G needle until it is no longer tense taking utmost precaution to avoid spillage. Some special devices have been developed for safe decompression of the cyst. The use of “cone” which adheres to liver surface by vacuum to prevent spillage have been described. Once no further fluid is aspirated a scolicidal agent is injected (provided the cyst fluid is not bile stained) and if it is hypertonic saline it is left for 10 minutes. Cyst is finally aspirated and larger incision is made to introduce large bore suction cannula. The remaining cyst fluid and solid contents are aspirated. Cyst is finally deroofed and remaining daughter cysts and germinal membrane are removed using sponge holding forceps. Cavity is finally inspected cautiously for a bile leak which is best demonstrated by packing the cavity with white colored pack left in place for 5–10 minutes and note any bile staining. If bile-stain appears a meticulous search for orifice of CBC is conducted aided by gentle squeeze of gall bladder if necessary. Intraoperative detection of CBC is essential for adequate management. Many authors have recommended intraoperative (cystic duct) cholangiogram. Cavity may then be irrigated with a scolicidal agent [11].

21.1 Management of CBC

1. Suture: majority of patients with CBC is with a peripheral and small duct and simple suture of the defect is sufficient

2. Drainage only

3. Suture plus T-tube

4. T-tube only

5. Drainage plus decompression of biliary tree- decompression is achieved externally by T-tube or internally by endoscopic papillotomy, trans duodenal sphincteroplasty, biliodigestive bypass

6. CBC with major duct: options are

   • Roux-en-Y cystojejunostomy

   • Roux-en-Y intracysticjejunostomy

   • Roux-en-Y hepaticojejunostomy

   • Intracystic bile duct repair

   • Liver resection

21.2 Management of residual cavity

1. Omentopexy

2. External drainage

3. Pericyst cavity left open

4. Simple closure of cyst cavity

5. Introflexion of the rim of pericyst

6. Capitonnage- spiral suturing from the bottom of the cyst cavity upwards

Most commonly used methods for management of remaining cavity are omentopexy and external drainage. Omentopexy is preferred when cyst is simple without CBC and external drainage is preferred in infected cyst and when CBC is present. Though omentopexy is an easy procedure most serious complication is ischemia of transposed omentum. Detection of recurrence by USG also becomes more difficult after omentopexy. Open cyst evacuation recurrence rate is 10–30% [17]. A RCT by Seyed Reza Mousavi et al. showed lower post operative complications (5.7 v/s 16.6%) and less mean hospital stay (6.5 v/s 15.6 days) in omentopexy group compared to external drainage group [19].

22. Laparoscopy

Laparoscopic surgery follows the same principles as in conventional open approach. Peripherally located Echinococcal liver cyst may safely be managed by laparoscopic cyst evacuation [18]. Excluding criteria for laparoscopic cyst evacuation are- deep intraparenchymal cyst, posteriorly situated cyst, more than three cysts, cysts more than 15 cm, cyst closer to vena cava and cyst with thick and calcified wall. The difficult part of the procedure is initial puncture of the cyst and to aspirate viscous particulate material, daughter cysts, laminated membrane and avoid spillage in the peritoneal cavity. To overcome this problem various techniques and instruments have been described with expected results:

1. Isolated hypobaric technique by Bickel

2. Aspirator grinder apparatus by Acarli

3. Perforator grinder apparatus (PGA) by Saglam

4. Liposuction cannula by Al-Shareef

5. Palanivelu hydatid system

23. Radical surgery

Pericystectomy involves removal of the cyst along with a rim of liver tissue in a non-anatomic plane. This is a major operation and involves major blood loss. Pre-operative localization of bile duct and vascular system is imperative. If a bile duct connection is suspected pre-op ERCP should be obtained. IOUS is also helpful. Pericystectomy decreases the risk of spillage of cyst content and also lower the risk of recurrence.

Sub- adventitial cystectomy—with the concept that pericyst consist of two layers, a plane is dissected between outer adventitial layer and inner avascular exocyst layer and as liver parenchyma is not dissected bleeding and bile leak is expected to be minimum.

Hepatic resection - Non- anatomic liver resection is actually the cystectomy procedure.

Anatomic liver resection - Rarely if the affected liver lobe is irreparably destroyed lobectomy is justified. E. multilocularis infection may lead to fulminant hepatic failure from sclerosingcholangitis or Budd-Chiari like syndrome and in these rare cases orthotopic liver transplantation may be necessary.

24. Complications of hydatid cyst surgery

1. Spillage: Spillage during intervention can lead to peritoneal hydatidosis which is to be avoided by any means

2. Recurrence: This is a serious problem in conservative surgery and left over exocyst is responsible for most recurrences. This also explains why recurrence is least with pericystectomy and hepatic resection. To detect exocyst IOUS plays a very important role.

3. Other various complications include wound infection, chest infection, subphrenic abscess, liver abscess, purulent collection residual cavity, residual obstacles in CBD, bile peritonitis, bile leakage and ischaemia of omentum in omentoplasty. Bile leakage is drainage of bile through abdominal drains for not more than 10 days. If it persists more than 10 days it is a biliary fistula. Depending upon the amount it can be low output fistula (less than 300 ml/day) or high output fistula (more than 300 ml/day). Low fistula usually heals spontaneously but high variety requires biliary decompression -ERCP and Papillotomy.

25. Pulmunary hydatid disease

The right lung and lower lobe are slightly more often involved. Uncomplicated cysts present as rounded or oval lesion on chest X-ray. Erosion of the bronchioles results in air being introduced between pericyst and laminated membrane and gives a fine radiolucent crescent “meniscus or crescent sign.” This is often regarded as a sign of impending rupture. When the cyst ruptures the collapsed endocyst floats in the residual fluid- “the water lily sign” on CT scan. Mainstay of treatment is surgery. Medical treatment is less successful and considered when surgery is not possible because of poor general condition or diffuse disease affecting both lungs or recurrent and ruptured cyst. The principle of surgery is to preserve as much viable lung tissue as possible. The exact procedures can vary from cystotomy, capittonage, pericystectomy, segmentectomy or occasionally pneumonectomy (Figure 5).

Figure 4.

Adrenal hydatid cyst specimen.

Figure 5.

Pulmunary hyadtid cyst post mortem specimen.

26. Vaccine

A defined antigen vaccine has been developed which can prevent hydatid disease in sheep and thus indirectly reduce the incidence of infection in human [20]. Vaccination of dogs also giving encouraging results. In future it is expected development of effective human vaccine against a parasitic disease.

27. Conclusion

Improvement in imaging supplemented with serology most cases of hydatid diseaae can be diagnosed with certainty. As the complications can be very serious most cases demand some form of treatment. Chemotherapy with albendazole is useful both in preoperative and post operative cases to prevent secondary echinococcosis. Although surgery is the gold standard, PAIR has emerged as a standard curative treatment with minimal complication. Future hope is the development of an effective human vaccine.

Conflict of interest

The author declare no conflict of interest.