Human Alveococcosis - Treatment, Symptoms, Analysis

2023 Author: Riley Dean | [email protected]. Last modified: 2023-11-27 09:15

Alveococcosis - a parasitic disease caused alveococcus and characterized by a primary lesion in the liver. Detection and treatment of this disease should be carried out as early as possible, as serious complications may occur.

The content of the article:

1 Alveococcosis
2 Sources of infection with alveococcosis
3 Alveococcosis - prevention
4 Clinical picture
5 Cycle of development of alveococcosis in humans (intermediate host)
6 Alveococcosis - symptoms
7 Alveolar echinococcosis
8 Complications of alveococcosis
9 Treatment of alveococcosis

Alveococcosis

Alveococcosis (synonym: alveolar echinococcosis, multi-chamber echinococcosis) is helminthiasis with predominantly liver damage. The causative agent of alveococcosis is the tapeworm Alveococcus multilocularis (alveococcus), in the mature stage parasitizing in the small intestines of the polar fox, fox, dog, wolf (final hosts), in the larval stage - in wild mouse-like rodents, humans (intermediate hosts). Sexually mature alveococcus has a length of 1.3-2.2 mm; at the front end of its body there is a head with 4 suckers and a rim of hooks; the head is followed by 2-4 segments. The larva of the helminth has the appearance of a node consisting of many small cells containing a yellowish liquid and scolexes (heads) of the parasite.

Epidemiology. Alveococcosis has a definite geographical distribution. In the USSR, it is found in Siberia, Yakutia, Kazakhstan, Bashkiria, Tataria, Kyrgyzstan.

Man and rodents become infected with alveococcosis through food contaminated with feces of the final hosts of the helminth (polar foxes, etc.), containing eggs and segments of the alveococcus.

Infection is also possible through contact with dogs, peeling and processing the skins of wild animals, drinking raw water from natural reservoirs, eating wild herbs and berries.

Pathological anatomy and pathogenesis. The liver with alveococcosis, as a rule, is enlarged, sharply compacted, with tumor-like nodes. The nodes are foci of productive necrotic inflammation with many helminth vesicles. Inside the node, the melting of dead tissue often occurs with the formation of cavities filled with a pus-like fluid. In the pathogenesis of alveococcosis, sensitization of the body with metabolic products and the decay of helminths, its mechanical effect on tissues, and secondary bacterial infection play a role.

Sources of infection with alveococcosis

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

The intermediate host is a human, murine rodents (voles, ground squirrels, gerbils, muskrats, beavers, nutria), which are a biological dead end. A person with alveococcosis is not a source of infection.

The mechanism of infection is fecal-oral or contact-household. A person becomes infected when visiting forests, meadows, picking mushrooms, berries, herbs seeded with eggs, drinking water from suspicious sources, hunting, cutting the skins of animals on whose wool there are oncospheres (eggs) of the parasite, caring for sick cats, dogs (rarely). One of the rare mechanisms of infection is aerogenic (air-dust path) - when oncospheres are inhaled with dust and get into the lungs.

Alveococcosis - prevention

Treatment of dogs infested with alveococcus and their hygienic maintenance. Compliance with hygiene rules when skinning arctic foxes, foxes. Thorough washing before eating wild berries and herbs.

Clinical picture

Alveococcosis affects people more often at the age of 20-35 years. The disease flows asymptomatically for many months and even years, until the patient notices a painless tumor-like formation in his right hypochondrium or Epigastrium, which forces him to consult a doctor, usually already with an advanced process. On palpation in these cases, a very dense, lumpy liver is determined, painless or slightly painful.

A parasitic "tumor" that has not reached a large size appears only when complications arise. The most common of them are necrosis and decay in the center of the node, which occurs as a result of compression of blood vessels by scars. Sudden hemorrhage into the decay cavity is possible, caused by the destruction of a small vessel. In these cases, pain, malaise, and sometimes a febrile condition appear due to infection of the affected area.

Alveococcosis. In other cases, the node, sometimes not large enough, but located near the large bile ducts or portal vein, can compress them, which leads to the development of jaundice or (very rarely) ascites. Other complications of alveococcosis (usually later) are the growth of a parasitic "tumor" into the adjacent organs (right kidney, diaphragm, stomach, etc.) and metastasis to the lung and brain.

The diagnosis of alveococcosis is usually made in the late stage of the disease, often mistaken for liver cancer. In natural foci of alveococcosis and in areas of the greatest distribution of this invasion, where the population is periodically examined for alveococcosis, early recognition is possible. Laboratory diagnosis is critical and is based on serological diagnostic tests that detect disease even before clinical signs appear.

Special allergic diagnostic tests are of great help. The most reliable of these is the Casoni reaction. A sterile filtrate of echinococcal bladder fluid from the affected lungs or liver of cattle is used as an allergen. The test is carried out intradermally. In case of a positive result (the reaction occurs after 20 minutes), a whitish bubble appears at the injection site, surrounded by a wide zone of skin hyperemia. After 24-48 hours. an infiltration forms at this place. Since the repeated conduct of the Casoni reaction can cause the development of anaphylactic shock, the Fishman reaction is more often used (see Echinococcosis). It is completely safe for the patient.

With alveococcosis, eosinophilia is often observed. With the help of an X-ray contrast study of the liver vessels, as well as a radioisotope study (scanning), it is possible in some cases to determine the localization of the alveococcosis node, and with peritoneoscopy (see) to see it and take pathological material for histological examination.

The prognosis for alveococcosis is serious. Patients die due to the development of obstructive jaundice, liver dysfunctions, less often from alveococcus metastases to the brain.

Surgical treatment. Due to the usually late diagnosis, radical removal of the nodes can be performed only in some patients. If a radical operation is not possible, emptying of decay cavities, palliative liver resections, bile diverting operations are indicated. Chemotherapy with antiparasitic drugs (injection of formalin, trypaflavin, etc.) is not effective enough.

The cycle of development of alveococcosis in humans (intermediate host)

Through the mouth (orally), oncospheres (eggs) enter the human small intestine, are freed from the outer shell, followed by the 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 of the oncospheres are retained in the liver, where larvocysts are formed. In rare cases, oncospheres overcome the hepatic barrier and reach other organs (lungs, spleen, heart, brain, and others).

The process of formation of polyamide cysts is long-term. Larvocyst in humans is formed over several years. Its growth occurs through the external or exogenous formation of bubbles or cysts, which gradually replace the tissue of the affected organ. With such growth, the entire architectonics of the organ is significantly disrupted - the vessels are affected, the function of cells, blood circulation is disrupted. In general, the process of germination of a larvocyst into organ tissue can be compared with the formation of a tumor. Individual bubbles with blood flow are carried into other organs, forming metastases (secondary foci).

Alveococcosis - symptoms

In the development of alveococcosis, asymptomatic, uncomplicated and complicated stages are distinguished. The nature of the course of alveolar echinococcosis can be slowly progressive, actively progressing and malignant. The preclinical stage of alveococcosis can last for many years (5-10 years or more). At this time, patients are worried about urticaria and itching. Detection of alveococcosis during this period usually occurs with the help of an ultrasound scan performed for another disease.

In the early manifest stage, the symptoms of alveococcosis are not very specific, include hepatomegaly, severity and dull pain in the right hypochondrium, pressure in the epigastrium, bitterness in the mouth, and nausea.

Examination often reveals an increase and asymmetry of the abdomen; on palpation of the liver, a dense node with an uneven bumpy surface is determined. Patients feel weakness, loss of appetite, weight loss. With alveococcosis, periodic attacks of hepatic colic, dyspeptic symptoms are possible.

The most common complication of alveococcosis is obstructive jaundice caused by compression of the biliary tract. In the case of a bacterial infection, a liver abscess may develop, which is accompanied by increased pain in the right hypochondrium, the appearance of hectic fever, chills, and torrential sweats. With the breakthrough of the parasitic cavity, purulent cholangitis, peritonitis, pleural empyema, pericarditis, pleurohepatic and bronchohepatic fistulas, aspiration pneumonia can develop. In case of compression of the liver gate by a tumor conglomerate, portal hypertension occurs, accompanied by varicose veins of the esophagus, esophageal and gastric bleeding, splenomegaly, ascites.

When the kidneys are interested, proteinuria, hematuria, pyuria develop, and a urinary tract infection joins. The consequence of immunopathological processes is the formation of chronic glomerulonephritis, amyloidosis and chronic renal failure.

Alveococcus metastasis most often occurs in the brain; in this case, focal and cerebral symptoms occur (Jackson attacks, mono- and hemiparesis, dizziness, headaches, vomiting).

A severe and transient course of alveococcosis is observed in patients with immunodeficiency, pregnant women, and those suffering from severe concomitant diseases. Often, alveolar echinococcosis ends in death.

Alveolar echinococcosis

Alveolar echinococcus (Echinococcus alveolaris; synonym: multichamber echinococcus, alveococcus) has a wide geographical distribution. Its foci were found in Germany, Switzerland, Austria, Siberia, on the island of St. Lawrence, Alaska, in North. Canada, Rebun Island in Japan, Commander Islands.

In the tape stage, alveococcus parasitizes mainly in foxes and arctic foxes and much less often in wolves, corsacs, dogs and cats. The larva of the alveococcus is built according to a special type that differs sharply from the larvocyst of cystic (hydatid) echinococcus; the parasite in the larval stage infects rodents (vole mice, muskrats, Ob lemmings, mole voles, ground squirrels, hamsters, etc.) and humans. The question of the possibility of affecting the larvocyst alveococcus of farm animals has not yet been fully studied. Echinococcus and alveococcus chains are similar to each other, but there are differences in their structure. The alveococcus tapeworm has a shorter body length, a greater number of segments, and a relatively shorter length of the last segment. The sexually mature segment in the alveococcus is the third from the end, and in the hydatid echinococcus - the second from the end, the testes in the alveococcus are twice as small. The uterus in the alveococcus is without lateral outgrowths, while in the hydatid echinococcus, the outgrowths are mostly clearly expressed. The hooks of the alveococcus are thinner than the hooks of the hydatid echinococcus. Alveococcus eggs are no different from hydatid echinococcus eggs.

A person becomes infected directly from foxes, arctic foxes and wolves when processing their skins or when eating berries, mushrooms, vegetables contaminated with their excrement and when drinking water. Somewhat less often, the source of infection is a dog that has eaten a rodent. Infection occurs in the same way as in hydatid echinococcosis. Alveococcus embryos most often settle in the liver (in about 95% of cases). Primary extrahepatic alveococcosis is extremely rare.

The main feature of the growth of alveococcus is the budding of the parasite, exogenous infiltrating vesicle growth, which resembles the growth of a malignant neoplasm. The alveococcus larvocyst in rodents contains a fairly large number of scolexes. In the nodes of the alveococcus in humans, scolexes are extremely rare.

The alveococcus node is a focus of productive-necrotic inflammation, penetrated by many vesicular larvae of the parasite and resembling a tumor node. During the operation and at autopsy, in the absence of experience, they often make an erroneous diagnosis of a malignant neoplasm, especially since the nodes do not push the liver tissue apart, but germinate it.

If, at autopsy, metastases in the lungs or in the brain are found, then the diagnosis of a malignant neoplasm seems even more likely; the error is detected only by histological examination. Tumor nodes are more often located in both lobes of the liver, less often - only in the left, can be single and multiple and, merging with each other, reach large sizes and weight (several kilograms). Areas of the liver not affected by the alveococcus are vicariously hyperplastic, especially in young people.

Complications of alveococcosis

in some cases, the tissue inside the nodes may disintegrate with the formation of a cavity with purulent contents - liver abscess, purulent cholangitis; if a cavity breakthrough occurs, then the patient's pain increases, the temperature rises;
inflammation of the tissue around the affected liver may occur - parihepatitis,
germination of the node into the gallbladder, ligaments, omentum, and through the diaphragm - into the lungs, pericardium, heart, kidneys;
systemic amyloidosis with kidney damage can lead to chronic renal failure.

Alveococcosis treatment

Therapeutic measures are similar to those for echinococcosis.

When making a diagnosis, hospitalization is required.

1) Surgical treatment with timely treatment and the absence of germination of nodes in nearby organs and tissues, as well as the absence of metastasis. In some cases, resection of the liver lobes is performed while preserving healthy tissue. All radical operations are carried out in only 15% of cases of alveococcosis.

2) Antiparasitic therapy (in the postoperative period and if surgical treatment is impossible) - albendazole 20 mg / kg / day is prescribed in long courses with interruptions with a total duration of 2 to 4 years. Treatment is carried out strictly under the supervision of the attending doctor 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 violation of the functional state of one or another affected organ).

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