Echinococcosis is one of the severe chronic helminthiases for humans, caused by a tapeworm of the species Echinococcus granulosus, namely one of its life stages - a larva. From it, in turn, occurs such a formation as a Finn, which is a bubble that can reach a fairly large size and weigh several kilograms due to the content of liquid in it.
Intermediate and final host
The intermediate host of this helminth can be not only humans, but also cattle, various rodents and other animals. Let us consider in more detail the life cycle of echinococcus. The parasite can begin its development in almost any organ or tissue, but most often this place is the liver and lungs. As a rule, echinococcosis is detected already in the later stages of development, since no clinical signs appear for the first few years, which is the main problem of this disease. The sexually mature helminth parasitizes in the intestines of canines, such as wolves, hyenas, jackals, dogs, so they are its definitive host.
Short descriptionEchinococcus granulosus
First of all, you need to understand what echinococcus is, as well as what are the features of its structure. It is distinguished from other representatives of the class by its small size: from 2 to 11 mm - the length of the strobila (a chain of segments of an adult tapeworm). It also has a neck, a scolex (head), equipped with a proboscis and a halo of hooks, and four suckers that serve to attach to the wall of the organ. The strobilus includes only, as a rule, 3-4 proglottids (segments), of which only the last one contains the vitelline gland, in which up to 800 eggs are formed.
Infection and epidemiology
Human (intermediate host) is infected by the oral route. It is known that the greatest distribution of echinococcus is observed in the southern regions. Australia has recorded a significant number of infections. In addition to the climatic factor, livestock plays a role. So, no less often the disease occurs in Kazakhstan, where sheep breeding is widespread. There, people who work in this field of activity are susceptible to echinococcosis by eating infected meat or liver. In addition, you can get sick because of unwashed vegetables and fruits, untreated water, which may contain viable echinococcus eggs. At present, for example, in a country like ours, a person can become infected through close contact with dogs, on the coat of which eggs or segments of the parasite may appear after defecation of the animal.
Echinococcus life cycle
Let's take a closer look at this issue. Life cycle of echinococcus (scheme of its development)uncomplicated. It all starts with the fact that the parasite develops in the small intestine of animals belonging to the canine family (dogs, rarely wolves). When an individual reaches full maturity, its segments, which are capable of independent movement, come out with the animal's feces, causing him severe itching. At the same time, the segment, which contains a huge number of eggs, bursts. Thus, the eggs of the parasite end up in the external environment: on the animal's fur, grass, water, and surrounding objects.
It should be noted that Echinococcus eggs, like other helminths, are resistant to the environment: they tolerate low temperatures, desiccation, and their viability, for example, in grass lasts up to 1.5 months. Thus, the life cycle of echinococcus begins in the eggs, which are then ingested by humans or other animals through water, fruits, or unwashed hands. In an infected organism, an invasive stage begins - a stage of development that occurs in a new host. Here, a larva emerges from each egg, called an oncosphere, which loses its thick shell and, with the help of its hooks, penetrates through a thin wall into a blood vessel, entering the liver with blood flow, then into the lungs. Then, through the systemic circulation, the oncosphere can penetrate into one or another organ, muscle or bone tissue.
New phase
Next, the life cycle of echinococcus enters a new phase, and the oncosphere turns into a Finn. Finn is a fluid-filled bladder containing a large number of scolexes. Herefinna grows, getting nutrients from the tissue in which it parasitizes.
Echinococcosis is a disease caused precisely at the finnose stage of worm development. Echinococcal bladder can be either single-chamber or multi-chamber. In humans, the first species is most often found, which has smaller bubbles on the surface - daughter ones. Thus, the echinococcal bladder, with its pressure on the surrounding tissues, disrupts the proper functioning of neighboring internal organs and affects the body with released toxins.
Also, the bubble can burst or start to fester, which is extremely dangerous and can even lead to the death of the patient. In this case, the released scolexes and small blisters will give an even wider spread of the disease. Only at this stage, due to the size, it becomes possible to identify the disease. In the earlier phases, the newest method is used, for which the size of the parasite does not matter - zepping.
For many years, surgery did not lead to a cure, as this results in a rupture of the Finns, and then intoxication, which leads to an even more serious, that is, widespread infection. After reviewing the life cycle of Echinococcus briefly, it is obvious that it continues in the body of the final (main) host, which becomes infected by eating the meat of the intermediate, in which Echinococcus cysts are located.
So, after it enters the body of the main host, the walls of the bladder dissolve under the action of digestive enzymes, as a result of which numerous scolexes are released, and with the helptheir two suckers, they are attached to the intestinal mucosa. Here the individual becomes sexually mature, which ends the life cycle of the helminth. Thus, it is important to understand that if the intermediate host was a person, then the life cycle of echinococcus finds its development in his body. It becomes a dead end in the Echinococcus cycle.
Main clinical signs
Uncovering the concept of what is echinococcus, life cycle, structure, scheme of its development, it is important to point out the symptoms of this helminthiasis. It is customary to distinguish three stages of the course of the disease, which do not depend on the localization of infection with the parasite. The exact duration of the course of the stages cannot be determined due to the slow growth of the echinococcus cyst. It should only be noted that the rate of increase in symptoms is associated with the localization of the parasite. The very first, latent or asymptomatic, stage begins with the penetration of the helminth into the body (invasion of the oncosphere) and lasts until the first signs, symptoms of echinococcosis appear. Characterized by the absence of any patient complaints.
Echinococcus cyst is usually found during this period by chance, for example, during various operations not related to this parasite, or during preventive examinations. However, sometimes an infected person may experience periodic itching, that is, urticaria or other allergic and general toxic reactions indicating echinococcus, the structure and life cycle of which are described above.
Next phase
Then comes the so-called symptom onset stage, which is characterized by mild symptoms of parasite infestation. Here, the echinococcal cyst is already significantly enlarged in size, it compresses neighboring tissues, which leads to the corresponding symptoms: dyspeptic disorders and, if the infection is localized, for example, in the liver, periodic dull pulling pains and liver enlargement (hypomegaly). This is how echinococcosis manifests itself in the initial stage. What is it, types, life cycle of this helminthiasis, prevention of its occurrence - the answers to all these questions are set out in our article.
Then comes the stage of development of complications, characterized by pronounced objective symptoms, which happens in 10-15% of infections. As already described above, suppuration of the echinococcal bladder (cyst) can occur, its rupture with the contents entering the hollow neighboring organs or the abdominal cavity. It may also be accompanied by obstructive jaundice due to obstruction of the bile ducts, portal hypertension and other symptoms that depend on the location of the helminth (lungs, liver, brain). For example, if the parasite has settled in the liver, weight loss, loss of appetite, vomiting, heartburn and belching can be noted.
It all ends with a stage of complicated invasion.
Shapes
Having understood what echinococcus is, echinococcosis disease, the stages of development of helminthiasis, it is necessary to dwell in more detail on its formsmanifestations. There are two types of echinococcus: hydatidosis and alveolar. Hydatidosis often affects the liver and forms a single-chamber bladder. Alveolar, in turn, affects the lungs and has a multi-chamber bladder. The symptomatology of echinococcosis does not depend on the form of the disease: in any case, the helminth develops and puts pressure on neighboring organs, increasing in size. However, due to their simpler structure, unilocular cysts are known to be easier to treat. To get rid of a multi-chamber bladder, surgical intervention is required, the success of which directly depends on the degree of cystic growth.
Treatment of echinococcosis
Among the main methods of therapy are the following: surgical treatment, antiparasitic and symptomatic therapy. During surgical intervention, the patient is removed echinococcal blisters, after which the affected organ or tissue is restored. In this case, the method of radical echinococcectomy is used, in which the cyst is completely removed along with the fibrous membrane.
Sometimes, a direct opening of the cyst is performed, removing all fluid and carefully disinfecting and cleaning the cavities and previously affected tissues to avoid a second, more global infection. In case of massive organ damage, the operation is not performed. Instead, antiparasitic treatment is prescribed with special drugs. In addition, in the fight against the symptoms of the disease, antihistamines, antitussives and others are used, depending on the form of echinococcosis.
Dispensary observation is necessary within 8-10 years after the operationat least twice a year.
Prevention of echinococcosis
Having studied in detail what echinococcus is, as well as the symptoms of the development of the disease, it is important to remember that the disease is easier to prevent by following the recommendations on preventive measures. To this end, special veterinary measures are taken to prevent infection of animals. It is also necessary to pay special attention to people at risk, that is, hunters, slaughterhouse workers, livestock breeders and others. As an individual prevention, first of all, you should follow the rules of personal hygiene, drink only from trusted sources, thoroughly wash vegetables, fruits and berries before eating, and also limit yourself from contact with stray dogs.
