Alveococcosis( alveococcus) - Causes, symptoms and treatment. MF.

Alveococcosis has a high prevalence on the planet. The incidence of this helminthiasis in endemic areas reaches up to 8-10 cases per 100 thousand of the population. Attention is drawn to the severity and severity of the lesion, the difficulty of drug treatment, and the lethality of the disease.

Alveococcosis( alveolar hydatidosis, multi-chamber parasitosis) is a parasitic natural focal disease of the human being caused by alveococcus multilocularis, characterized by a severe course with the formation of a primary focus - multicameral cysts in the liver( less often single-celled), the ability to spread and form peculiar metastases( secondary foci), having a tendency to chronic course, high lethality.

Alveococcosis, causative agent

Geographic distribution of alveococcosis

In the world there are natural foci of alveococcosis, where the causative agent of helminthiosis circulates, which are provided by the presence of certain wild sources of infection( animals).In the world these are the countries of Central Europe, Central and South America, Northern Canada, Alaska, Central Asia, Transcaucasia, Russia - the Far East, Western Siberia, the Kirov region and others. In northern countries, the circulation of the causative agent of alveococcosis is supported by lemmings, white foxes, in southern countries - voles moths, muskrats, foxes and others.

Causes of alveococcus formation

Alveococcus multilocularis or larval stage of Echinococcus multilocularis. There is a certain similarity with the causative agent of echinococcosis. Sexually mature female - cestoda - up to 3.5-4 mm in length. In the structure, the head( scolex), neck and joints are distinguished from 2 to 5.The number of hooks on the scolex is up to 30, the terminal mature segments have a globular uterus with eggs. Eggs similar to echinococcal( the egg contains an oncosphere - 6-tikruchnuyu larva-fetus).Differential larvocysts( pathological cysts), formed by alveococcus. Larvocysts are multi-chambered, contain a lot of vesicles( excretory capsules), within which there are 1 to 3 scolexes( parasite heads).Each laervocyst is up to 0.5 mm in size, their congestion gradually forms, and they grow outside, affecting the tissues of the organ. This is the formation of a multi-chamber or alveolar cyst. On the cut, the cyst has a cellular structure with foci of necrosis in the center. Most often, the overall dimensions of the multicameral cyst do not exceed 10-15 cm in diameter, but in rare cases reach large sizes.

Alveococcosis, knot on the

incision Sources of infection with alveococcosis

The final host of alveococcus in wild foci is fox, wolf, arctic fox, jackal, and in synanthropic( close to humans) - a dog, a cat in which the sexually mature cestodes parasitize. With feces, mature segments and eggs are released into the environment.

Intermediate host is a human, a mouse-like rodent( voles, ground squirrels, gerbils, muskrats, beavers, nutria), which are a biological dead end. A person with alveococcosis, the source of infection is not.

The mechanism of infection of is fecal-oral or contact-household. A person becomes infected when visiting forests, meadows, gathering mushrooms, berries, herbs, eggs, using water from suspicious sources, hunting, cutting animal skins, on the wool of which there are onkosfery( eggs) of the parasite, care for sick cats, dogs( rarely).One of the rare mechanisms of infection - aerogenic( air-dust path) - by inhalation of oncospheres with dust and getting them into the lungs.

Alveococcosis, sources of invasion

Susceptibility to alveococcosis is universal, but due to certain moments of infection, people of young and middle age( 30-50 years old) fall ill.

Cycle of development of alveococcosis of animals ( final host): the cycle of development is similar to the cycle in echinococcosis. Infection occurs when eating intermediate hosts - rodents, in which the larval stage of alveococcus( larvocysts or multicameral cysts) is formed in the body. In the intestine of the final host from the scleras of the larvocysts, sexually mature specimens - cestodes are formed, the number of which may be large. The sexually mature individual is formed in 35 days in the final host. By this time, oncospheres( eggs) are formed in the terminal segments-up to 800 eggs. The duration of parasitization and, accordingly, the release of oncospheres into the environment can last for 6-7 months.

Cycle of development of alveococcosis in human ( intermediate host): through the mouth( orally) oncospheres( eggs) enter the small intestine of the person, are released from the outer shell with the subsequent stage of introduction into the intestinal mucosa. Here they penetrate into the blood and lymphatic vessels, then into the portal vein and with the blood flow reach the liver. Most oncospheres stay in the liver, where larvocysts are formed. In rare cases, the oncosphere overcomes the hepatic barrier and reaches other organs( lungs, spleen, heart, brain and others).

The process of formation of multicameral cysts is continuous. A man's larvocyst is formed over several years. Its growth occurs by external or exogenous formation of vesicles or cysts, which gradually replace the tissue of the affected organ. With this growth, the whole architectonics of the organ is significantly disturbed - the vessels are affected, the function of the cells, blood circulation is disrupted. In general, the process of germinating the larvocyst in the tissue of the organ can be compared with the formation of a tumor. Separate vesicles with blood flow are entered into other organs, forming metastases( secondary foci).

Alveococcus, larvocyst in the liver

Pathological effect of alveococcus on the human body

1) Sensitization of the body( toxic-allergic action of the products of the vital activity of the parasite - toxins).
2) Mechanical compression of affected organs and tissues with a growing multi-chamber larvocyst( node, cyst), as a result of which the function of the affected organ is significantly impaired, which entails a number of related problems. For example, a violation of liver function leads to "flooding" with toxins of the general blood flow and the threat of toxic damage to the kidney tissue, brain and other organs. With liver damage, mechanical jaundice, foci of necrosis in the liver develops. In 90% of cases, alveococcosis is associated with a primary lesion of the liver.
3) The emergence of metastases( secondary foci) in different organs( lungs, brain, adrenal glands, heart, spleen and others).
4) Immunodeficiency and development of autoimmune reactions( own antibodies destroy the affected cells).

What is the focus of alveococcosis ( node ​​alveococcus, cyst alveococcus) - a conglomeration of vesicles with foci of inflammatory necrotic process in size from 0.5 to 35 cm in diameter. Vesicles are formed exogenously and, due to the absence of a dense capsule, actively spread into healthy liver tissue. The process resembles the growth of a malignant tumor. In the environment of the vesicles connective tissue proliferates - fibrosis is formed. It is possible to attach secondary infection with the danger of abscess formation, sprouting into the bile ducts and development of cholangitis. In the foreseeable future, the process can go far with the formation of biliary cirrhosis.
Often the protracted process is incompatible with the patient's life.

Immunity in alveococcosis is similar to that of echinococcosis - unstable, but repeated invasion of alveococcus is not described.

Symptoms of alveococcosis

For a long time( years) the disease is asymptomatic, the patients do not complain. Patient's state of health is satisfactory. Suspicion occurs when an objective examination of the patient - reveals enlarged liver, dense, bumpy to the touch.

The manifest( clinically pronounced) stage of alveococcosis develops several years after the invasion and development of the larvocysts. Allocate the early stage, the stage of the height of the disease, the stage of severe manifestations, the terminal stage.

The early stage of is characterized by the appearance of the first signs of impaired liver function: the patient is worried about the periodic painful character in the liver region( right hypochondrium), a feeling of heaviness, some decrease in appetite, weakness. When examining the patient at this stage, the alveococcal dense knot can be propalped, but with its central location it is difficult to do. Laboratory at an early stage the character of the proteinogram changes: the total amount of protein in the blood serum increases, the amount of gamma globulins increases, the ESR increases.

The stage of swelling of the is characterized by the progression of the disease: pain in the liver area becomes almost constant, pains appear in the epigastric region, indigestion signs - a feeling of heaviness after eating, belching, stool disorders, patients complain of decreased appetite, weakness. On examination, the liver is still enlarged in size, but more pronounced, along with inflamed areas of a dense-elastic consistency tissue, dense multiple nodes are sensed - the so-called "stony density of the liver".Laboratory - moderately expressed increase in the number of eosinophils to 15%, an increase in ESR, a more pronounced disproteinemia: the total protein increases significantly( up to 110 g / l at a rate of 65-85 g / l), a decrease in albumins, a pronounced increase in gamma globulins( up to 60%at a rate of 12-19%), a C-reactive protein was raised in a biochemical blood test, and a thymol test( a sign of mesenchymal inflammation of the liver) was increased.

In the stage of severe manifestations of , we see the development of one or another severe manifestation of organ failure by alveococcus. Most often, this development of mechanical jaundice: the patient's stools lighten up to a grayish white color, at the same time dark urine begins, the sclera and mucous membrane of the oral cavity begin to yellow, then the skin of the face, limbs, trunk. Jaundice with a mechanical obstruction is intense, stagnant, sometimes with a slight greenish tinge. Also, patients are concerned about skin itching on the limbs, back. Laboratory - an increase in the amount of bilirubin due to a direct fraction, an increase in the number of bile pigments in the urine.

Sometimes alveococcal nodes grow into large vessels( portal veins, inferior vena cava), in which signs of portal hypertension - ascites( fluid in the abdominal cavity), edema of the legs, varicose veins of the esophagus, danger of bleeding.

With a far-reaching process, secondary metastatic foci are formed in other organs and tissues. Most often these are the lungs, the brain, the heart, kidneys, bones. Half of the patients will be bothered by damage to the kidney tissue with the development of glomerulonephritis( damage to the glomerular apparatus of the kidneys) - there may be pain syndrome in the projection of the kidneys, a change in the color of urine, a violation of urination. The cause of kidney damage is associated either with metastasis of the process, or with mechanical compression of the kidney tissue from the outside. In the analysis of urine protein( proteinuria), erythrocytes( erythrocyturia), leukocytes( leukocyturia), pus( pyuria).

The terminal stage of alveococcosis is very difficult. Violations of the function of the affected organs become irreversible, patients lose weight sharply, immunodeficiency is expressed, complications develop.

Complications of alveococcosis:

- in some cases inside the nodes the tissue can decay to form a cavity with purulent contents - liver abscess, purulent cholangitis;if there is a break in the cavity, the patient's pain increases, the temperature rises;
- inflammation of the cellulose around the affected liver can occur - pariphepatitis,
- germination of the node into the gallbladder, ligaments, epiploon, and through the diaphragm - into the lungs, pericardium, heart, kidneys;
- Chronic renal failure may result in systemic amyloidosis with kidney damage.

Diagnosis of alveococcosis

Preliminary diagnosis - clinical and epidemiological. A careful collection of the epidemiological history in the previous few years before the disease will largely clarify the picture. The region of residence, the patient's lifestyle, the likelihood of infection when visiting forests, hunting, contacting animals, the degree of occupational risk of invasion, and others are of great importance. Clinical data allow suspicion of alveococcosis only a few years after infection.

The final diagnosis is carried out in a complex way using laboratory methods, specific laboratory studies, instrumental methods.

1) laboratory methods - general blood analysis( eosinophilia, increase in ESR), proteinogram( increase in total protein, decrease in albumins, increase in gamma globulins), biochemistry( increase in bilirubin due to direct fraction, increase in thymol test, AF), general urine analysis(proteinuria, hematuria, leukocyturia are possible) and others;
2) serological responses to antibodies to alveococcus( RNGA, ELISA, latex agglutination reaction);
3) instrumental research methods( ultrasound, MRI, CT, X-ray);

Alveococcosis, node on CT

4) targeted biopsy of the node with laparoscopy( performed only with 100% exclusion of echinococcosis in order to avoid fatal outcome for the patient);
5) microscopic examination of sputum for the purpose of detection of alveococcus;

Differential diagnosis is performed with echinococcosis, liver cirrhosis, malignant and benign neoplasms, polycystic liver disease, hemangioma, tuberculosis.

Treatment of alveococcosis

Treatment measures are similar to stacking in echinococcosis.
When hospitalization is required, hospitalization is mandatory.

1) Surgical treatment of with timely treatment and absence of germination of the nodes in nearby organs and tissues, as well as the lack of metastasis. In some cases, resection of lobes of the liver with preservation of healthy tissue is carried out. Radical operations are carried out all in only 15% of cases of alveococcosis.
2) Antiparasitic therapy ( during the postoperative period and when surgical treatment is not possible) - Albendazole 20 mg / kg / day is prescribed for long courses with interruptions with a total duration of 2 to 4 years. Treatment is carried out strictly under the supervision of the attending physician in order to avoid complications of therapy( toxic effect of the drug) and timely correction of the changes that have appeared.
3) Symptomatic therapy ( depending on the impaired functional state of a particular affected organ).

Clinical follow-up of patients who underwent alveococcosis

Patients are monitored for life. Once in 6 months, an ultrasound scan( or other instrumental examination) is performed in order to cause a possible relapse, monitor blood tests, biochemical analyzes, and conduct all necessary studies.

Prevention of alveococcosis

1) Compliance with the rules of personal hygiene, as well as the rules of visiting nature with the possibility of processing hands before eating.
2) Deratization measures to prevent the spread of patients with alveococcosis of rodents.
3) Prophylactic deworming every six months of domestic animals( dogs, cats).

The doctor infektsionist Bykova N.I.