Echinococcosis is one of the most severe chronic helminthiases for humans, the cause of which is the tapeworm of the species Echinococcus granulosus, namely, one of its vital stages - the larva. From it, in turn, there is such an formation as a Finn, which is a bubble, which can reach a sufficiently large size and weigh several kilograms due to the content of liquid in it.
Intermediate and final host
An 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 to develop 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 late stages of development, since the first few years no clinical signs are manifested, which is the main problem of this disease. A sexually mature helminth parasitizes in the intestines of canids, for example wolves, hyenas, jackals, dogs, so they are its ultimate host.
Brief description of Echinococcus 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). He also has a neck, a scolex (head), equipped with a proboscis and a nimbus of hooks, and four suckers, which are used to attach to the organ wall. The strobila includes, as a rule, only 3-4 proglottids (a segment), of which only the last contains yolk, in which up to 800 eggs are formed.
Infection and epidemiology
A person (intermediate host) becomes infected by the oral route. It is known that the greatest distribution of echinococcus is observed in the southern regions. In Australia, a considerable number of infections have been recorded. In addition to the climatic factor, livestock production plays its role. So, at least the disease is found in Kazakhstan, where sheep breeding is common. There echinococcosis affects people who work in this field of activity, when eating contaminated meat or liver. In addition, you can get sick due to unwashed vegetables and fruits, untreated water, which can contain viable echinococcus eggs. At present, for example, in a country such as ours, a person can become infected by close contact with dogs, on the hair of which there may be eggs or segments of the parasite after defecation of the animal.
Echinococcus Life Cycle
Let us consider this question in more detail. The life cycle of echinococcus (the scheme of its development) is simple. It all starts with the fact that the parasite develops in the small intestine of animals belonging to the canine family (dogs, less often wolves). When an individual reaches full maturity, its segments, which are capable of independent movement, go outside with the stool of the animal, causing itching severely. At the same time, the segment, which contains a huge number of eggs, bursts. Thus, the parasite's eggs are in the external environment: on the animal’s hair, grass, water, objects surrounding it.
It should be noted that Echinococcus eggs, like other helminths, are resistant to the environment: they tolerate low temperatures, dry out, and their viability, for example, in the grass lasts up to 1.5 months. Thus, the life cycle of echinococcus begins in the eggs, which then enter the body of a person or other animal through water, fruit or unwashed hands. In the infected body, the invasive stage sets in - the developmental stage that takes place in the new host. Here, from each egg, a larva emerges, called the oncosphere, which loses its thick shell and, with the help of its hooks, penetrates through a thin wall into a blood vessel, falling into the liver and then into the lungs with a current of blood. Then, in the large circle of blood circulation, the oncosphere can penetrate into one or another organ, into muscle or bone tissue.
New phase
Further, the life cycle of echinococcus enters a new phase, and the oncosphere turns into Finnish. Finn is a fluid-filled bubble containing a large number of scolexes. Here, Finn grows, receiving nutrients from the tissue in which it parasitizes.
Echinococcosis is a disease caused precisely at the finnous stage of the development of the worm. Echinococcal bladder can be either single-chamber or multi-chamber. In humans, the first species most often occurs, having smaller bubbles on the surface - daughter ones. Thus, an echinococcal bladder, by its pressure on the surrounding tissues, disrupts the proper functioning of neighboring internal organs and affects the body with excreted toxins.
Also, the bubble can burst or begin to fester, which is extremely dangerous and can even lead to the death of the patient. At the same time, the released scolexes and small bubbles will give an even wider spread of the disease. Only at this stage, due to size, is it possible to detect the disease. In the earlier phases, the latest method is used, for which the magnitude of the parasite is not important - tapping.
For many years, surgery did not lead to a cure, since the Finns rupture and then intoxication, which leads to an even more serious, that is, widespread infection. After the echinococcus’s life cycle is reviewed briefly, it is obvious that it continues in the body of the final (main) host, which becomes infected by eating intermediate meat, in which echinococcal 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 help of their two suction cups they are attached to the intestinal mucosa. Here, the individual becomes sexually mature, which ends the helminth's life cycle. Thus, it is important to understand that if a person was an intermediate host, then the echinococcus life cycle finds its development in his body. It becomes a dead end in the cycle of development of echinococcus.
The main clinical signs
When revealing the concepts of what is echinococcus, the life cycle, structure, and the scheme of its development, it is important to indicate the symptoms of this helminthiasis. It is customary to distinguish three stages of the course of the disease, independent of the localization of the parasite infection. The exact duration of the stages cannot be determined due to the slow growth of echinococcus cysts. It should only be noted that it is with the localization of the parasite that the rate of increase in symptoms is associated. The very first, latent or asymptomatic, stage begins with the penetration of helminth into the body (invasion of the oncosphere) and lasts until the onset of the first signs, symptoms of echinococcosis. It is characterized by the absence of any complaints of the patient.
An echinococcus cyst is usually found during this period by chance, for example, during various operations not associated with this parasite, or during preventive examinations. However, sometimes an infected person may experience occasional itching, that is, urticaria or other allergic and general toxic reactions that indicate echinococcus, the structure and development life cycle of which are described above.
Next phase
This is followed by the so-called stage of the onset of symptoms of the disease, which is characterized by mild signs of infection with the parasite. Here, the echinococcal cyst is already significantly enlarged, 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 enlarged liver (hypatomegaly). So manifests itself in the initial stage of echinococcosis. What is it, types, life cycle of a given helminthiasis, prevention of its occurrence - the answers to all these questions are set out in our article.
Next 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) may occur, its rupture with the contents getting into the adjacent hollow organs or abdominal cavity. It can 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, decreased appetite, vomiting, heartburn, and belching can be noted.
All this ends with a stage of complicated invasion.
Forms
Having understood what echinococcus, echinococcosis disease, and the stages of development of helminthiasis are, it is necessary to dwell on the forms of its manifestation. Two types of echinococcus are distinguished: hydatidose 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, it is known that, due to its simpler structure, single-chamber cysts are 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 proliferation.
Treatment of echinococcosis
Among the main methods of therapy are the following: surgical treatment, antiparasitic and symptomatic therapy. During surgical intervention, echinococcal vesicles are removed to the patient, 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 carried out, removing all the fluid and thoroughly disinfecting and cleaning the cavities and previously diseased tissues in order to avoid repeated, more global infection. In the case of massive organ damage, the operation is not performed. Instead, prescribe antiparasitic treatment with special drugs. In addition, antihistamines, antitussive and others are used to combat the symptoms of the disease, depending on the form of echinococcosis.
For 8-10 years after surgery, follow-up is required at least twice a year.
Echinococcosis Prevention
Having studied in detail what echinococcus is, as well as 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. For this purpose, special veterinary measures are carried out 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 prophylaxis, first of all, you must 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.