Alveolar echinococcosis: causes, symptoms, diagnosis, treatment

Alveolar echinococcosis (alveococcosis multicentric echinococcosis, Latin alveococcosis, English alveococcus disease) is a zoonotic chronic leukemia that is characterized by the development in the liver of cystic structures capable of infiltrative growth and metastasis to other organs.

ICD-10 codes

• D67.5. Liver invasion caused by Echinococcus multilocularis.
• 867.6. Invasion of other localization and multiple echinococcosis caused by Echinococcus multilocularis.
• 867.7. Invasion caused by Echinococcus multilocularis, unspecified.

Epidemiology of alveolar echinococcosis

The source of alveolar echinococcosis for humans is the final hosts of the helminth. Mature eggs and segments, filled with eggs, are released into the environment with faeces of animals. Infection occurs when a person enters the mouth of the environment from the environment during hunting, processing the skins of killed wild animals, eating forest berries and herbs seeded with helminth eggs. Oncospheres of alveococcus are very resistant to the action of environmental factors: they carry the temperature from -30 to +60 ° C, on the soil surface at a temperature of 10-26 ° C remain viable for a month.

Alveococcosis is a natural focal disease. The factors determining the activity of the outbreaks are the abundance of intermediate hosts (rodents), large areas (meadows, pastures) that do not plow, a cool rainy climate. Diseases are mostly noted among individuals. Visiting natural foci for professional or domestic needs (picking berries, mushrooms, hunting, hiking, etc.). As well as among the workers of animal farms. Mark and family cases of infection. There is no pronounced seasonality. Men are more often ill at the age of 20-40 years, children are ill rarely.

In Russia, the disease occurs in the Volga region. Western Siberia, Kamchatka, Chukotka, the Republic of Sakha (Yakutia), the Krasnoyarsk and Khabarovsk Territories, in the CIS countries - in the republics of Central Asia, Transcaucasia. Endemic foci of alveococcosis are found in Central Europe, in Turkey, Iran, in central China, northern Japan, Alaska, and Northern Canada.

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

What causes alveolar echinococcosis?

Alveolar echinococcosis is caused by Alveococcus multilocularis, which develops with a change of hosts. The final hosts of alveococcus are carnivorous animals (foxes, arctic foxes, dogs, cats, etc.). In the small intestine of which the sexually mature forms are parasitized. Intermediate hosts are rodents. Sexually mature A. Multilocularis in structure is similar in structure to the ribbon stage of E. Granulosus, but smaller (1.6-4 mm in length), the head is provided with one aperture of short hooks, the uterus is spherical. But the main difference is in the structure of the Finn, which in A. Multilocularis has the appearance of a cluster of vesicles and is a conglomerate of exogenously budding small vesicles filled with liquid or gelatinous mass. In humans, vesicles often do not have scolex. The growth of the Finns has been slow, for several years.

Pathogenesis of alveolar echinococcosis

In humans, the larva of A. Multilocularis develops 5-10 years or more. The development and growth rates of the parasite can be caused by the genetic characteristics of the indigenous population in endemic foci. The larval form of the alveococcus is a dense, small-bellied tumor, which consists of a conglomerate of small vesicles. On the cut, it resembles a fine-porous cheese. The alveococcal knot is the focus of productive necrotic inflammation. Around the foci of necrosis, a granulation shaft is formed containing living alveococcus vesicles. Alveococcus features - infiltrating growth and the ability to metastasize, which brings this disease closer to malignant tumors. The liver is always affected. Most often (75% of cases) the parasitic focus is localized in its right lobe, less often in both lobes. Perhaps a solitary and multinodal lesion of the liver. The parasitic nodes are roundish, ivory, 0.5 to 30 cm or more in diameter, of iron-like density. Parasitic node can sprout into the bile ducts, diaphragm, kidney. Compensation of the function of the organ is possible due to hypertrophy of the uninjured parts of the liver. In the complicated stage of alveolar echinococcosis in the center of the alveococcal nodes, cavities of necrosis (caverns) of various shapes and sizes almost always appear. The wall of the cavity in places can become thin, which creates the prerequisites for its rupture. Actively multiplying vesicles of the parasite in the peripheral zone of the node are introduced into the liver tissue along the course of the vascular-duct structures, into the gallbladder. Obstructive jaundice develops, in later stages - biliary cirrhosis. The alveococcal nodule can sprout into adjacent organs and tissues (small and large omentum, retroperitoneal tissue, diaphragm, right lung, right adrenal and kidney, posterior mediastinum). Possible metastasis in the lymph nodes of the retroperitoneal tissue, lungs, brain, bones.

In the pathogenesis of alveolar echinococcosis an important role is played by immunological and immunopathological mechanisms (immunosuppression, formation of autoantibodies). It is established that the rate of growth of the larva depends on the state of cellular immunity.

Symptoms of alveolar echinococcosis

Alveococcosis is found primarily in young and middle-aged people. Often, the disease for many years is asymptomatic (preclinical stage). The stages of the disease are distinguished: early, uncomplicated. Complications and terminal stage. In the clinically manifested stage, the symptoms of alveolar echinococcosis are poorly specific and depend on the volume of parasitic lesion, its localization and the presence of complications. By the nature of the flow, slowly progressing, actively progressing and malignant currents are distinguished by alveolar echinococcosis.

The first symptoms of alveolar echinococcosis are an enlargement of the liver, which is usually discovered by chance. Patients report a feeling of pressure in the right hypochondrium or in the epigastric region. There is a feeling of heaviness and a dull, aching pain. Often noted increase and asymmetry of the abdomen. A dense liver with an uneven surface is palpable through the anterior abdominal wall. The liver continues to increase, becoming woody-dense, tuberous and painful on palpation. Patients noted such symptoms of alveolar echinococcosis as weakness, deterioration of appetite, weight loss; as a rule, significantly increased ESR. They detect unstable eosinophilia, lymphopenia, anemia is possible. Early hyperproteinemia with hypergammaglobulinemia appears. The indicators of biochemical samples remain for a long time within the limits of the norm. At this stage, obstructive jaundice, most characteristic of the central localization of the parasitic tumor, most often develops. It starts without a pain syndrome and grows slowly, it is accompanied by itchy skin, increased concentration of bound bilirubin, activity of alkaline phosphatase. In cases where a bacterial infection joins, a clinical picture of liver abscess develops. The penetration of the contents of the parasitic cyst into the bile ducts is rare. When the cavity is opened, bronchopyonous, pleuropeic fistula can be formed, peritonitis, pleurisy, pericarditis develop. Portal or caval hypertension occurs less often than jaundice. Symptoms of portal hypertension (vein dilatation in the anterior abdominal wall, varicose veins of the esophagus and stomach, hemorrhoidal veins, splenomegaly, hemorrhagic manifestations, ascites) occur in the late stages of alveococcosis. The most dangerous complication of portal hypertension is bleeding from the veins of the esophagus and stomach. Metastases are most often found in the lungs, the brain, and more rarely in the kidneys, bones. More than 50% of patients observe renal syndrome: proteinuria, hematuria, pyuria, cylindruria. The defeat of the kidneys is due to compression of the body from the outside or due to metastases, a violation of renal blood flow and passage of urine with the development of urinary tract infection. Due to the attachment of immunopathological processes, chronic glomerulonephritis is formed, a systemic amyloidosis with chronic renal insufficiency. More severely and transitory alveococcosis occurs in visitors in endemic foci, in persons with immunodeficiency, during pregnancy and with its interruption, with severe concomitant diseases.

Diagnosis of alveolar echinococcosis

Diagnosis of alveolar echinococcosis is based on epidemiological history, clinical laboratory and instrumental studies.

Serological diagnosis of alveolar echinococcosis is used: RLA, RIGA, ELISA; PCR can be used, but a negative reaction does not exclude the presence of alveococcosis in the subject.

X-ray studies, ultrasound, CT and MRI allow us to assess the degree of organ damage. On the overview radiographs of the liver in the patient with alveococcosis, small calcification centers can be seen in the form of so-called calcareous sprays or calcareous lace. Laparoscopy is also used for targeted biopsy of the alveococcus node, but it can be performed only after exclusion of hydatid echinococcosis. In obstructive jaundice caused by alveococcosis, both visual (EGDS, laparoscopy) and direct radiopaque methods (retrograde pancreatoholangiography, antegrade, percutaneous, transhepatic cholangiography) are used. The advantage of these methods of research, in addition to high information content, is the possibility of using them as therapeutic measures, mainly for decompression of bile ducts.

[7], [8], [9], [10], [11], [12]

Differential diagnosis of alveolar echinococcosis

Alveococcosis of the liver must be differentiated from hydatinosic echinococcosis, neoplasms of the choledochocampic region, amebic abscess, liver cirrhosis.

[13], [14], [15],

Treatment of alveolar echinococcosis

Indications for consultation of other specialists

Operative treatment of alveolar echinococcosis is carried out after the surgeon's approval.

The regime and diet are indicated in the course of a complicated course of alveolar echinococcosis disease.

Chemotherapy treatment of alveolar echinococcosis is used as an additional agent. Apply albendazole in the same doses and regimen as with hydatidid echinococcosis. The duration of the course of treatment depends on the patient's condition and the tolerability of the drug. With severe jaundice, violations of the liver and kidney function, suppuration of the decay cavity, in the terminal stage of the disease, antiparasitic treatment is not recommended.

If possible, a total surgical removal of the alveococcal node of the liver within intact tissues is carried out. With bleeding from the esophagus, the most effective method of conservative treatment is squeezing the esophagus by the Blackmore probe. Palliative surgery in combination with chemotherapy can improve the patient's condition for a long time. In recent years, more than 50 liver transplants have been performed in different countries around the world in patients with alveolar echinococcosis, however, in spite of a thorough preoperative study, there are many cases of recurrence of the process or metastasis.

Forecast

Serious if it is impossible to surgically treat alveolar echinococcosis.

[16], [17], [18], [19],

Clinical examination

Clinical follow-up after the postoperative operation lasts 8-10 years with the examination not less than once in 2 years. Only persons who showed a negative result with a three- or four-time serological examination within 3-4 years are taken off the account. When there are clinical signs of recurrence or an increase in antibody titres in serological reactions, an in-hospital examination is shown. Patients with inoperable forms of the disease remain disabled, and monitoring them for life.

[20], [21], [22]

How to prevent alveolar echinococcosis?

Alveolar echinococcosis is prevented by the same methods as in hydatidid echinococcosis.