Echinococcosis

Echinococcosis is a disease associated with penetration into the human body and development in it of the larval stage of the ribbon echinococcus worm (Echinococcus granulosus).

ICD-10 code

B-67. Echinococcosis

What is echinococcosis?

The echinococcus worm in the sexually mature state parasitizes in the intestine of the final host, the dog. The number of worms in the body of the final host can reach several thousand. The worm consists of a head with four suckers and hooks, two or three segments, the last of which contains a uterus filled with parasite eggs. The number of eggs reaches 400. Each egg has a dense chitinous membrane and contains a larva. Echinococcus eggs secretes into the environment, where they are eaten by intermediate hosts (sheep, cows, pigs and camels). In their body, the intermediate stage of the parasite develops - the cystic. After the death or slaughter of intermediate hosts, the diseased organs of animals are eaten by dogs, in the body of which sexually mature worms subsequently develop. Thus, the cycle of development of echinococcus closes.

A person becomes infected with echinococcus by accidentally eating eggs of a parasite. After ingestion of eggs of echinococcus into the human body, their membrane under the influence of gastric juice dissolves, and the released larva penetrates through the gastric or intestinal wall into the blood stream and is introduced into the capillaries of the liver. In 80% of infected patients there it gets stuck and begins to develop. If the larva passes the capillaries of the liver, it is injected with a blood stream into the capillaries of the lungs, where it can also linger and cause lung damage. A similar situation is observed in about 15% of cases. If the larva passes through the capillaries of the lungs or penetrates into the large circle of circulation through the open oval window, it can be introduced into any organ or tissue of the body (spleen, kidneys, brain, subcutaneous tissue, etc.).

In the liver, the larva of the parasite actively grows, turning into a vial a month later with a diameter of up to 1 mm, and after five months the bladder can reach 55 mm. Echinococcal bubble is constantly growing due to the nutrients of the host and can eventually reach a volume of 10-20 and even 30 liters. Echinococcal cyst has a characteristic structure and has apposition growth, pushing out surrounding tissues, but not germinating them. It is filled with a clear liquid containing succinic acid. From the inside, the formation is lined with a single-layered cubic epithelium (a growth layer). Outside it is a dense chitinous membrane - the product of the vital activity of the parasite. It has a white color and is similar in appearance to the protein of the boiled egg. Outside the cystic formation is surrounded by a dense connective tissue fibrous capsule, which consists of the tissues of the host's organism and fences it from the parasite. With prolonged existence of the cyst, the fibrous membrane can reach a thickness of up to 1 cm or more. Inside the echinococcal cyst from the growth layer bud daughter bubbles, from which, in turn, buds bubble, and so on. In addition, it contains many parasitic embryos (echinococcal sand) that float in the liquid.

Epidemiology

Echinococcosis is widespread mainly in countries with developed livestock. People who are associated with the service of domestic animals, such as shepherds, milkmaids, as well as persons who have contact with dogs, especially children who play with them, allow their pets to lick their faces and sniff food.

Echinococcosis is most common in Latin America, where up to 7.5 diseases per 100 000 population per year are recorded. It is also found in Central Asia, Australia, New Zealand and Europe. From European countries, the disease is common in Italy, Bulgaria and Iceland. In Russia, it is registered primarily in the Caucasus, along the middle and lower reaches of the Volga, in Western Siberia, Yakutia (Sakha) and Chukotka. Mostly people of young, working age are ill, but the disease is also detected in young children and in the elderly. Recently, the disease is recorded outside endemic foci, which is associated with an increase in population migration.

[1], [2], [3], [4], [5], [6], [7], [8],

How is echinococcosis manifested?

Echinococcosis and its manifestations depend on the location and size of the cysts.

In the first period of the disease (in the asymptomatic stage), patients may be bothered by allergic reactions of the organism to the introduced parasite: skin itching, urticaria, the appearance of papules on the skin. These symptoms are characteristic of any helminthic invasion and are especially pronounced in children. In the physical examination of the patient at this stage, it is usually impossible to identify any deviations. Help in diagnosis can only special laboratory and instrumental examination.

In the uncomplicated course, patients with echinococcosis complain of dull constant pain and a sense of heaviness in the right hypochondrium, dyspeptic phenomena and a feeling of overflow of the stomach after meals. At objective research at a part of patients reveal in formation of the round form, densely elastic consistency and slightly morbid at a palpation.

In the stage of severe clinical manifestations and complications, the clinical picture of the disease is quite pronounced. Patients with echinococcosis are disturbed by constant dull pain and a feeling of heaviness in the right hypochondrium. With palpation in the liver, you can identify a "tumor" of a rounded shape, a dense elastic consistency, sometimes reaching a large size. Occasionally, over the tumor, one can observe "noise of trembling hydatides." Children with large sizes of cysts often observe a deformation of the chest - "echinococcal hump." Further manifestations depend on the nature of the developed complications.

Echinococcosis of the liver can undergo aseptic necrosis followed by calcification. In this case, a stony density is formed in the liver, which can be identified by palpation and special methods of investigation. The general condition of the patients suffers little, and the clinical picture is limited by the presence of pain, a feeling of heaviness in the right hypochondrium and impaired appetite with progressive weight loss. When the cysts are suppurated, the symptoms correspond to the manifestations of liver abscess: the patient's severe condition, hectic temperature with signs of an inflammatory reaction in the blood test, severe permanent pain in the right upper quadrant.

A growing cystic formation can squeeze out the bile ducts. In a similar situation, the patient is diagnosed with mechanical jaundice with icteric staining of the skin and sclera, skin itching, discoloration of feces and darkening of urine. Patients become flaccid and adynamic. When the veins in the portal collapses, there are symptoms of portal hypertension with the appearance of ascites, splenomegaly, esophageal and hemorrhoidal hemorrhages.

Due to minor trauma, a large cystic formation can break into the free abdominal or pleural cavity and even into the pericardial cavity, as well as into the bile ducts. A cyst breakthrough is characterized by the development of severe allergic shock, which can be fatal. If a patient with echinococcosis remains alive, then he has echinococcal peritonitis, pleurisy, or pericarditis. At the same time, the daughter blisters and scolexes of the parasite released into the cavity are fixed on the peritoneum and the pleura, where they begin to progress and develop. The number of such cysts in the abdominal cavity can reach several tens. With the breakthrough of the cyst into the biliary tract after anaphylactic shock, rapidly flowing cholangitis develops and mechanical obstruction of the bile ducts with the development of mechanical jaundice.

Approximately in 5-7% of cases when the cyst is located on the diaphragmatic surface of the liver, the lung fuses with the diaphragm and, when breaks of the cyst, a message is formed between its cavity and the bronchial tree. A fistula is formed in the gall-bronchial fistula. The clinical picture of this complication is quite typical. Complaints about a cough with the allocation of a large amount of transparent sputum and films - scraps of chitinous cyst shell. In the future, sputum becomes bilious. The amount of it increases after meals and in the position of the patient lying, which causes patients to sleep sitting.

Echinococcosis of the lung manifests itself by pains in the chest and shortness of breath. With suppuration of the bladder, an abscess of the lung is possible, in the case of bursting of the bladder, a painful cough and hemoptysis suddenly appear in the bronchi, the contents of the echinococcal bladder are excreted from the bronchi - scraps of shells and scolexes.

With echinococcosis of other localizations, the symptoms of a body lesion dominate.

In connection with the belated diagnosis of echinococcosis, the incidence of complications in patients is high and usually is 10-15%.

Classification

There are three clinical stages of echinococcosis:

• asymptomatic stage;
• stage uncomplicated flow;
• stage of complications.

By diameter, the cysts are divided into the following:

• small (up to 5 cm);
• average (5-10 cm);
• large (11-20 cm);
• giant (21 cm and more).

[9], [10], [11], [12], [13], [14],

Screening

Screening studies are possible and appropriate in foci of echinococcosis among the most affected populations (livestock keepers, shepherds, agricultural workers). Conduct an examination, perform immunological reactions and ultrasound.

How to recognize echinococcosis?

Laboratory and instrumental research

In the presence of live echinococcal cyst in the blood, changes characteristic for helminthic invasion (eosinophilia and increased ESR) are observed. With the development of liver failure, the activity of transaminases (aspartate aminotransferase and alanine aminotransferase) increases. With mechanical jaundice, the concentration of direct bilirubin of blood serum and urobilin of urine increases.

On a special place in the diagnosis of echinococcosis are immunological reactions. In 1911, Tomaso Casoni proposed a reaction, which later received his name. He injected the patient intradermically with 0.1 ml of echinococcal fluid, and in the opposite forearm - isotonic sodium chloride solution. On the side of the introduction of fluid, redness appeared and a papule formed. Since then, this reaction has become widely used for the diagnosis of echinococcosis.

Cough's reaction is positive in about 90% of patients, but its specificity is too small. In connection with this, for the improvement of diagnosis, a number of other immunological responses have been proposed (hemagglutination, complement fixation, etc.). The possibility of developing an anaphylactic shock, especially when carrying out repeated immunological reactions, significantly limits their use in everyday clinical practice. With the introduction of new diagnostic tools in practice, these reactions have lost their original meaning.

Currently, the "gold standard" in the diagnosis of echinococcosis is ultrasound. Due to its non-invasiveness, availability and effectiveness, it is very convenient, and it is usually sufficient to establish an accurate diagnosis. In this case, it is possible to detect the presence of cysts in the liver, their size, location, the presence of daughter blisters and to determine the nature of the blood flow in the cyst zone during Doppler study.

With the calcification of the cyst, the survey radiography reveals a rounded, sometimes rimmed, shadow in the liver. A high diagnostic value is possessed by CT, which helps to solve many tactical issues of treatment.

With the introduction of ultrasound and CT in a wide clinical practice, such invasive methods for the diagnosis of echinococcosis, such as celiacography, portohepatography, laparoscopy and radioisotope study of the liver, have lost their significance.

Differential diagnostics

Echinococcosis usually requires differential diagnosis with other focal lesions of organs - cysts, benign and malignant neoplasms and alveococcosis. When suppuration cysts should be differentiated with a bacterial abscess, and with mechanical jaundice - with other causes. A decisive role in differential diagnosis should be given to anamnesis and modern instrumental methods of research.

Epidemiological anamnesis (place of residence, nature of work, contact with dogs), the presence of eosinophilia and the detection of focal lesions of the liver, lungs or other organs make it possible to clarify the diagnosis.

[15], [16], [17], [18], [19], [20], [21],

Example of the formulation of the diagnosis

Echinococcosis of the liver (uncomplicated or complicated) with the indication of complications (calcification, suppuration, breakthroughs in the body cavity, bronchial tree, portal hypertension, mechanical jaundice).

[22], [23], [24], [25]

How is echinococcosis treated?

Objectives of treatment

The goal of treatment is the removal of parasitic cysts from the liver, lungs and other organs and the creation of conditions conducive to preventing the recurrence of the disease. All patients with echinococcosis need treatment in a surgical hospital.

Surgery

Indications

The presence of echinococcosis of internal organs serves as an absolute indication for surgical intervention.

Contraindications 

Only the presence of severe concomitant diseases and intolerance of the operation make it necessary to refrain from the operation. The volume and nature depends on the size of the echinococcal cyst, its topography and the presence of complications.

[26], [27], [28], [29]

Methods of surgical treatment

For operation on the liver, two-folded access is more often used, allowing to inspect all parts of the liver and perform an intervention. Many surgeons are limited to median laparotomy or an oblique incision in the right upper quadrant.

The most radical operation is the resection of the liver within healthy tissues. Indications for its implementation are:

• multiple echinococcosis with localization of cysts within a fraction or half of the liver;
• the marginal location of the cyst;
• recurrent echinococcosis.

Pericystectomy is an operation of excising the cyst along with a fibrous capsule with minimal damage to the liver tissue. The operation is quite radical, it can be accompanied by severe blood loss, so it is necessary to use modern methods of hemostasis.

The most common and sufficiently safe for the patient operation is considered echinococcectomy. In this type of surgical intervention, the cyst is punctured initially and an antiparasitic agent, eg tincture of iodine, is injected into its lumen. Then the cyst is opened and the contents (daughter blisters, fluid and echinococcus sand) along with the chitinous membrane are removed. Further, the walls of the fibrous capsule are treated with glycerol, formalin or iodine tincture and closing of the remaining cavity by suturing (capitonage), gluing or tamponade with an omentum on the stem. In recent years, reports have appeared that frequent enough relapses after such an intervention are associated with the penetration of the parasite's scores into the cracks in the fibrous capsule. To improve the results of echinococcectomy, it was suggested to partially excise the walls of the fibrous capsule and treat the remaining tissues with glycerin, a laser beam or a cryodestructor (Fig. 34-8). Today, a certain proportion of patients with echinococcectomy have been performed using laparoscopic techniques.

Percutaneous puncture of the cyst with the removal of its contents and the introduction of sclerosing substances is permissible in exceptional cases when the cystic formation is single, marginal and without daughter blisters. This intervention is fraught with the development of anaphylactic shock and generalization of the process when entering the abdominal cavity of the echinococcus fluid.

Possible postoperative complications

The most serious complications after surgery for echinococcosis are hepatic insufficiency, blood flow and bile in the abdominal cavity. After interventions on the cysts of subdiaphragmatic localization, often there are jet basal pleurisy.

Conservative treatment

In recent years, albendazole and its derivatives have been used to treat echinococcosis. The drug is prescribed courses of 10-20 mg per kilogram of the patient's body weight per day. The course of treatment lasts 30 days. After 15 days, the course is repeated. To cure a patient, 3-5 such courses are necessary. Medicamentous treatment is often used as a supplement to surgical to prevent relapse of the disease and in patients who are not available for surgery due to the severity of concomitant diseases. The effectiveness of treatment with albendazole hydatid echinococcosis of the liver and lungs is 40-70%.

[30], [31], [32], [33], [34]

Further management

After radical interventions for a disease such as echinococcosis patients need inpatient treatment for two weeks. In those cases where the residual cavity heals with a secondary tension for a long time, hospital treatment is increased up to a month or more. If the postoperative period is favorable, a month later, the patient can start working, not related to physical activity. The latter are permissible after 3-6 months after the patient's recovery.

All patients after interventions for echinococcosis due to a sufficiently high risk of recurrence (10-30%) are recommended to conduct treatment with albendazole and subsequent dispensary observation. Follow-up ultrasound should be performed 3-6 months after the operation for timely detection of a possible relapse of the disease. After radical interventions on echinococcosis and the conduct of courses of drug treatment, patients are, as a rule, practically healthy and able-bodied. In the detection of recurrences of echinococcosis disease, repeated intervention is necessary.

How to prevent echinococcosis?

The main role in infecting a parasite is played by non-observance of hygiene rules. Prevention measures are well developed and include state and personal prevention. State prevention consists in decreeing the prohibition on domestic cattle slaughter. Cattle should be slaughtered only at meat processing plants or special veterinary sites with the culling and destruction of organs affected by echinococcus. Effects on echinococcosis of the final hosts in endemic foci include the destruction of stray dogs and de-worming of service dogs and domestic dogs twice a year. Personal prophylaxis is strict adherence to correct hygiene, especially after contact with animals.