Echinococcosis (echinococcus)
Echinococcosis is widespread in countries with hot climates, or in regions traditionally involved in animal husbandry. The density of patients with echinococcosis in Russia is 1-4 recorded cases per 100 thousand people. The peculiarity of the pathology is scanty symptoms at the beginning of the development of helminthiasis and, as a result, late diagnosis of the disease.
Echinococcosis is a chronic helminthiasis caused by the tapeworm of Echinococcus granulosis. The parasite invades the internal organs of humans and animals (usually the lungs and liver). Their functions are seriously impaired, echinococcal cysts are formed in the tissues. The area of development of the disease is occupied by the countries of Southern Europe (Italy, Cyprus, Greece, Bulgaria, Spain), the countries of South America (Brazil, Argentina). Echinococcosis is often found in the southern states of the USA, India, Japan, Australia.
In Russia, residents of territories and regions with extensive development of animal husbandry are most often infected: Khabarovsk, Krasnoyarsk, Stavropol, Krasnodar, Altai Territories, Omsk, Tomsk Regions, Bashkiria, Tatarstan.
Content:
- Reasons for the development of echinococcosis
- Pathological action of echinococcus in the human body
- Echinococcosis symptoms
- Diagnosis of echinococcosis
- Echinococcosis treatment
- Prevention of echinococcosis
Reasons for the development of echinococcosis
The cause of infection with echinococcosis is the introduction of the tape parasite Echinococcus granulosis into the body at the larval stage. This tapeworm is 2.5 to 8-9 mm long and consists of 3-4 segments, a neck and a head with 50 hooks in 2 rows and four suction cups.
The segments have different degrees of maturity:
- 1-2 immature segments;
- hermaphroditic segment;
- a mature segment containing a uterus with several hundred eggs.
Each of them contains a larva in the embryonic stage, which has 6 hooks. This larva (oncosphere) remains viable under the most extreme conditions: temperatures from -30 ° C to + 35 + 40 ° C. It can be in the ground for several months at temperatures from +12 to + 25 ° C. Only exposure to sunlight for several days is detrimental to the larva.
Sources of echinococcus infection
Ultimate host:
- Dogs,
- Coyotes,
- Foxes,
- Lions,
- Wolves,
- Jackals,
- Lynx.
Intermediate host:
- Sheeps,
- Proteins,
- Buffaloes,
- Hares,
- Horses,
- Pigs,
- Person.
The placental barrier is not an obstacle to the transmission of helminthiasis from mother to fetus.
Circulation scheme of parasitic invasion:
- The ultimate host.
- Environment, as a place of excrement with segments and oncospheres.
- An intermediate host or a healthy definitive host.
A person does not excrete with feces either eggs or segments of the helminth, so he cannot be a source of echinococcosis.
Echinococcosis infection mechanisms
A person becomes infected with echinococcosis in two ways: alimentary and contact-household. The introduction of parasites into the human body occurs when contaminated vegetables and fruits, contaminated water are included in the diet, when herbs and berries are collected, contaminated with animal feces, and when they come into contact with the hair of the main and intermediate hosts (mainly dogs).
A short cycle of development of echinococcus in animals:
- The final host (wolf, dog) eats the insides of the intermediate host (pig, hare, squirrel).
- An adult helminth that produces eggs develops on the mucous membrane of the small intestine of the final host.
- With feces, the mobile segments with the eggs of the larvae enter the environment.
- The eggs of the larvae remain in the internal environment until they reach a new host.
A short cycle of development of echinococcus in humans:
- Echinococcus eggs orally enter the human intestine.
- From the oncosphere, the embryo enters the bloodstream, through the portal vein it enters the internal organs.
- In the lungs or in the liver, a single-chamber bubble with a liquid is formed, consisting of a chitinous and an embryonic membrane. In the bubble, the stage of larval development occurs, additional daughter bubbles are formed.
- Inside the cyst, capsules form for the formation of scolexes, sometimes separating from the walls and floating in the liquid.
- The total weight of bubbles in one person can reach several tens of kilograms and contain up to 6-10 liters of liquid.
Pathological action of echinococcus in the human body
The main feature of echinococcosis is the formation of cysts in any organ. Most often it is the lungs (20%), the liver (80%). The cyst can be either singular or plural.
Consequences of the introduction of echinococci into the body:
- Sensitization of the body (immediate or delayed allergic reaction, anaphylactic shock when the cyst ruptures).
- Mechanical effect of an overgrown echinococcal cyst (atrophy and organ dysfunction). Consequences - tissue fibrosis, pulmonary pneumosclerosis. The term for the formation of a bubble structure from the moment the larva enters the body is on average 2 weeks. After 4-5 months, the size of the cyst can reach 5 mm. A cyst reaches a volume of several liters in a period of 10-20 years.
- Decrease in general and local immunity, re-infection due to a weak immune response of the body.
Echinococcosis symptoms
Stages of development of echinococcosis:
- Asymptomatic stage (from the onset of infection to the appearance of the initial cyst).
- The appearance of minor symptoms of infection in a particular organ.
- The emergence of a pronounced clinical picture of echinococcosis.
- Development of complications of helminthiasis.
The stages are conditionally highlighted, since the disease has a slow rate of development of symptoms, and cysts are formed extremely slowly.
Symptoms of liver echinococcosis
Common symptoms:
- Nausea and vomiting;
- Weakness;
- Loss of appetite;
- Pain in the epigastric region and right hypochondrium;
- Skin rash and itching;
- Diarrhea;
- Hepatosplenomegaly (enlargement of the spleen and liver);
- Isolation of the cyst on palpation;
- Inflammation of the cyst when a bacterial infection is attached (hyperthermia, chills, pain);
- Liver abscess;
- Obstructive jaundice in case of compression of the bile ducts by a cyst (dark urine, light stools, yellowing of the sclera of the eyes and skin, pruritus, an increase in the number of leukocytes and eosinophils).
When the cyst is opened, the patient experiences severe pain, manifestations of allergies, symptoms of anaphylactic shock. A severe consequence of a violation of the integrity of the cyst is the seeding with echinococcus of the whole body, secondary echinococcosis.
Find out more: Causes and symptoms of liver echinococcosis
Symptoms of pulmonary echinococcosis
Common symptoms:
- Pain in the chest, in the projection of the lungs;
- Dyspnea;
- Hemoptysis;
- Weakening of breathing;
- Shortening percussion;
- Deformation of the chest with mediastinal displacement;
- The development of exudative pleurisy with pleural effusion.
If the integrity of the cyst in the bronchi is violated, the patient feels suffocation, a strong cough, severe allergic manifestations are noted, he has cyanosis of the skin. When a cyst breaks into the pericardial cavity and the pleural cavity, death occurs due to anaphylactic shock.
A general blood test records leukocytosis with a shift towards stab neutrophils and eosinophils.
Find out more: Causes and symptoms of pulmonary echinococcosis
Symptoms of echinococcosis of the spleen, kidneys, central nervous system
It occurs extremely rarely when echinococci get into the systemic circulation. Symptoms - allergic urticaria, signs of damage to a specific organ.
Diagnosis of echinococcosis
When examining a patient by a helminthologist or infectious disease specialist, an epidemiological history is collected. The doctor analyzes whether the patient has close contact with animals, whether he is associated with animal husbandry, whether he often visits nature.
Methods of instrumental and laboratory diagnostics:
- Abdominal ultrasound, lung x-ray, CT for diagnosing cysts with one or more cameras. Taking a puncture from a cyst is not allowed, so as not to spread the infection to other organs.
- Serological blood test by the methods of RNIF, ELISA, RNGA for the detection of antibodies to echinococcus. This analysis has a high sensitivity (98%). The study is based on such a feature of the body of patients with echinococcosis as the release of specific antibodies into the blood.
- Study of biological fluids of the body (urine, sputum, contents of the duodenum) to detect the segments and scolexes of the parasite.
- General clinical studies - blood biochemistry (for AST, ALT, bilirubin, GGTP), general blood test (for the content of leukocytes and eosinophils).
Echinococcosis treatment
Echinococcosis treatment methods:
- Surgical removal of cysts with echinococci and restoration of the function of an organ previously affected by parasites. Helminths are removed in two ways: they radically remove the cyst together with its membrane, or open it with the removal of fluid, disinfect the cavity, drain it and sew it up tightly. During the operation, extreme care is required to avoid re-infection. The affected tissues are isolated, preventing the larvae from entering the abdominal and chest cavities.
- Antiparasitic treatment (carried out in case of massive damage and the impossibility of an operation). The main drug is Albendazole, it is prescribed in courses from 3 weeks to several months. The intervals between courses, the number of which can reach twenty, are 3-4 weeks. Relapses occur in 25% of patients, and in 41-75%, treatment is effective. An alternative is Mebendazole, taken for 15-24 months. The drugs are prescribed after surgery to prevent unnoticed contamination by helminth larvae, as well as to patients with antibodies to the parasite, but without the formation of cysts.
- Symptomatic therapy aimed at relieving complications and other symptoms. These are antihistamines, antitussives, hepatoprotectors.
To prevent the spread of helminthiasis, the following measures are applied:
- Examination for echinococcosis of persons at risk: livestock breeders, employees of meat processing plants and slaughterhouses, dog breeders, hunters.
- Veterinary measures for the prevention of infection of animals: compliance with sanitary standards for slaughtering and cutting livestock, prevention of helminthiasis in dogs.
- Compliance with the rules of personal hygiene: thorough washing of berries, vegetables and fruits, the use of purified water, hand treatment with soap and disinfectants after contact with dogs, caring for animals, before eating.
Author of the article: Danilova Tatyana Vyacheslavovna | Infectionist
Education: in 2008 received a diploma in General Medicine (General Medicine) at the Pirogov Russian Research Medical University. Immediately passed an internship and received a diploma of a therapist
