Alveococcosis

Alveococcosis is a disease associated with ingestion and development in it of larvae of the tapeworm Alveococcus multilocularis.

ICD-10 code

B-67. Alveococcosis

Epidemiology

Alveococcosis is a disease with pronounced endemicity. Foci of the disease are observed in Germany (Bavaria and Tyrol), southern France, Alaska, northern Japan (Hokkaido Island), Azerbaijan, Armenia, Kyrgyzstan, Uzbekistan and Kazakhstan. In Russia, alveococcosis has been registered in Bashkortostan, the Kirov region, Western Siberia, Yakutia (Sakha), Kamchatka and Chukotka. Mostly young people get sick. More often they are hunters, pickers of berries, people engaged in dressing animal skins and fur farm workers caring for foxes and foxes of cellular breeding. But there are cases of diseases in young children under 5 years old and in the elderly.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11],

What causes alveococcosis?

Alveococcosis is caused by the ribbon worm alveococcus. It is a flat worm 2-6 mm in size, consisting of a head with four suckers and hooks, two or three segments, the last of which is occupied by the uterus, containing up to 400 eggs. Each egg is surrounded by a dense, resistant to external influences shell and contains the larva of the parasite. Sexually mature worm parasitizes in the small intestine of the final hosts - red and black-silver foxes, arctic foxes, wolves and corsacs. The number of worms in the body of one animal can reach several tens of thousands. Parasite eggs naturally escape into the environment, where they are eaten by intermediate hosts of alveococcus - mouse-like rodents (field mice, ground squirrels, lemmings, gerbils, river beavers and nutria). Final hosts become infected, eating intermediate, and the cycle of development of alveococcus in nature is completed. After eating the intermediate hosts, mature sexually mature worms grow up on the 22nd-42nd day.

A person becomes infected by accidentally eating alveococcus eggs. Under the action of gastric juice, the egg shell dissolves, the released larva penetrates into the blood and enters the liver. Since the size of the larva of the alveococcus considerably exceeds the diameter of the capillaries of the human liver, it almost always lingers there and begins to develop. The larva turns into a small vesicle 2-4 mm in diameter and actively reproduces by budding. Thus, a parasitic "tumor" appears, consisting of many small parasite vesicles located in the connective tissue stroma of the liver, which gives the parasitic "tumor" a very large density. The alveococcus node on the cut has the appearance of porous fresh bread and consists of a number of chitinous vesicles of the parasite.

Unlike echinococcus, the alveococcus parasitic node secretes an enzyme called hyaluronidase, which melts surrounding tissues. Thus, the alveococcus node grows into the surrounding tissues and organs - the liver gate, diaphragm, lung, adrenal gland, kidney, pancreas, stomach, aorta and pericardium. Germination of alveococcus in the lymphatic and blood vessels leads to the fact that individual vesicles come off and the current of lymph and blood is transferred to the regional lymph nodes, lungs and brain, where they also begin to develop, forming metastatic nodes. The individual parasite bubbles left in the operation also give rise and provide relapse of the disease. This ability of alveococcus to germinate into surrounding tissues and organs, to give metastases and relapses makes alveococcosis downstream very similar to malignant liver tumors. The only difference is the slower growth of the parasitic node. Since the parasite is fed by diffusion of the host's nutrients, a more turbulent life reigns on the periphery of the node - the alveococcus bubbles actively multiply and the node grows. At the same time, at the center of it, due to lack of nutrition, a part of parasitic elements die and cavities of decay - parasitic caverns - form. They are in most cases filled with aseptic pus. In a number of cases, the parasitic caverns break through into the neighboring body cavities - the abdominal, pleural and pericardium.

How does alveococcosis manifest?

The clinical picture of alveococcosis depends mainly on the stage of the flow and the complications that exist. Anamnestic data in patients with alveococcosis are quite typical. This is living in endemic areas. By occupation, most often they are agricultural workers, especially hunters, skin parters, pickers of berries and fur farm workers.

In the asymptomatic stage, patients usually do not complain of alveococcosis. There can be only allergic manifestations of a parasitic disease - hives and itchy skin. In a stage of uncomplicated course of patients disturb constant dull pains and feeling of gravity in the right upper quadrant, sensation of overfilling of the stomach. During the physical examination, in most cases, hepatomegaly and local enlargement of the liver due to the parasitic node in it are noted. In this case, the node has a stony density.

With the suppuration of the parasitic cavern pains in the right hypochondrium increase, there is a hectic temperature, chills and heavy sweats. When breakthrough cavities in the body cavity develops a violent picture of peritonitis or pleurisy.

Blockade of the gates of the liver leads to portal hypertension and mechanical jaundice. When portal hypertension appears ascites, dilated veins of the abdominal wall, hemorrhoidal hemorrhage and bloody vomiting. With the compression of the bile ducts, icteric staining of the skin and sclera occurs, the urine darkens, the feces become discolored, and skin pruritus arises.

When breakthrough cavities breakdown in the abdominal cavity there is a sudden sudden pain and there are symptoms of increasing peritonitis. A breakthrough into the pleural cavity leads to the development of purulent pleurisy with respiratory failure, dulling of percussion sound and the presence of fluid in the pleural cavity.

Classification

Alveococcosis has three stages of flow:

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

Among the complications are: mechanical jaundice, portal hypertension, sprouting into neighboring organs, choledochondral fistulas, breakthroughs of cavities into neighboring cavities, metastases, atypical mask forms.

[12], [13], [14], [15],

Screening

Screening examination is advisable to be carried out in endemic areas, especially among hunters and staff of fur farms, caring for animals and participating in their slaughter. It is recommended to conduct clinical examinations, immunological reactions and ultrasound of the liver.

How to recognize alveococcosis?

Laboratory and instrumental research

Alveococcosis is characterized by eosinophilia, which in some cases reaches significant degrees, an increase in ESR, hypoalbuminemia and hypergammaglobulinemia. In advanced cases, the serum content of bilirubin increases, and with the development of liver failure, the activity of transaminases increases. The reaction of the Casoni with the echinococcal antigen in alveococcosis is positive in 90% of the cases. This explains the genetic affinity of both parasites. The specificity of immunological reactions (complement and hemagglutination binding) is rather high. These reactions, with the development and introduction into a wide practice of new radiation research methods, have lost their dominant role in the diagnosis of the disease.

The "gold standard" in the diagnosis of alveococcosis is now considered to be ultrasound. During it, you can determine the size, shape, topography of the parasitic node, its relationship with the elements of the gates of the liver and the inferior vena cava and the presence of a parasitic cavity and sequesters in it. Doppler ultrasound can detect a lack of blood flow in the area of the parasitic node and enhance it around the existing "tumor", in contrast to the true tumor.

A huge amount of information is given by CT. The increasing availability of this method of research makes it possible to refrain from such complex and risky methods of examination as arteriography and splenoportography. At a roentgenography on soft pictures in a shadow of a liver at half of patients the centers of a calcification in the form of "limy splashes" define.

Differential diagnostics

Alveococcosis is differentiated mainly with malignant tumors of the liver. On clinical manifestations, both diseases are very similar. Consider a significant difference in the dynamics of the process. In malignant tumors, the progression of the pathological process takes place fairly quickly. In alveococcosis in adults, the disease is relatively slow. But with the defeat of children with alveococosis, the pathological process is quite intense. Ultrasound and CT with biopsy can verify the diagnosis.

Epidemiological anamnesis (residence in endemic area, occupation - hunters, fur farm workers), positive immunological reactions, eosinophilia in peripheral blood, data from ultrasound and CT help in determining the correct diagnosis.

[16], [17], [18]

Example of the formulation of the diagnosis

Alveococcosis of the liver. Stage: asymptomatic, uncomplicated, stage of complications (breakthroughs, mechanical jaundice, portal hypertension, cholelithiasis, metastases).

[19]

How is alveococcosis treated?

Objectives of treatment

In treatment, the goal is to remove the parasitic node, eliminate complications or eliminate the most painful symptoms of the disease in inoperable cases.

Surgery

Drug treatment can only be used as an adjunct to surgical intervention or in the extremely serious condition of the patient. With alveococcosis, only liver resection within healthy tissues can heal a patient for alveococcosis. In connection with the long asymptomatic course of the disease, operability is low enough and, according to different authors, is from 25 to 40%. With total liver damage, the only radical method of treatment is liver transplantation.

With a severe condition of the patient for alveococcosis and the presence of a large parasitic cavity, the operation of marsupialization is performed. In this case, the front wall of the decay cavity is excised, the cavity is emptied of the contents and sequestration, and its edges are hemmed to the edges of the wound. In this case, it is also possible to destroy part of the parasitic tissue with the help of cryo-action. In the future, there is a partial rejection of parasitic tissue through the wound and healing by secondary tension. Subsequently, in a number of cases, it is possible during a repeated intervention to remove radically or partially the parasitic node from the liver.

Mechanical jaundice in a number of patients can be eliminated with the help of various biliary excrements or stenting the ducts through parasitic tissue, which does not heal the patient, but facilitates his condition. Gyno-bronchial fistulas can be eliminated by resection of the lung that carries the fistula and the effect on the parasitic node in the liver. With single metastases in the lungs or brain, it is possible to remove the focus provided a radical or palliative effect on the main parasitic node in the liver.

Possible postoperative complications

Among the postoperative complications, the most formidable is liver failure, which occurs after liver resections, especially enlarged ones. To reduce the risk of its development can be through careful preoperative preparation, careful operation with reliable hemostasis and active hepatoprotective and replacement therapy in the postoperative period.

Mortality after resection of the liver with alveococcosis is 5%.

Further management

After radical resection of the liver, a patient with alveococcosis is disabled for 2-3 months, and then can return to work. After palliative resections of the liver, patients remain healthy for 10 or more years, if the intervention was performed using cryotechnics. After palliative interventions the patient is transferred to a disability.

All patients operated on for alveococcosis need regular follow-up with an ultrasound monitoring once every 6 months to detect a possible recurrence or progression of the process after palliative interventions. It is recommended to conduct courses of treatment with albendazole.

How to prevent alveococcosis?

Prevention of the disease consists in observing the rules of personal hygiene, especially when slaughtering animals with cellular contents, dressing skins and harvesting berries. Workers of fur farms should carefully observe the rules of personal hygiene and have protection (mittens, armlets and aprons) when caring for animals and especially when slaughtering them.

Full prevention of alveococcosis disease is very difficult because the cycle of parasite development is mainly confined to wild animals, the impact on which is minimal on the part of the human, and dogs are rarely the final hosts of alveococcus.