So far, science knows about 280 types of worms that can develop and live in the human body, parasitizing on various organs and tissues. The frequency of infection by human worms depends on the climatic and socioeconomic conditions of specific territories (in underdeveloped countries, especially those located in tropical and subtropical areas, the level of parasitic infections is much higher than in economically developed countries).
Forms of human helminth infection
- Biohelminthiasis (infection of animals).
- Contagious helminthiasis (transmitted from person to person).
- Geohelminthiasis (diseases caused by parasites that carry out one of their life cycles on earth).
Factors affecting the manifestations of helminthiasis
- The way the parasite enters the body;
- The degree of adaptation of helminths to the human body;
- Population density (number) of parasitic individuals;
- The worm habitat (the parasites of the tissues live in the thickness of the soft tissues and the luminaries live in the lumens of hollow organs). Some helminths in different phases have luminous and tissue forms. The larval and developing stages of worms, as a rule, cause more pronounced pathological changes.
In the absence of reinfection, the number of adult parasites in the human body does not increase. This characteristic significantly distinguishes helminthic invasions from diseases caused by bacteria, viruses, fungi and protozoa.
Worms in humans: symptoms
Helminthiasis is a disease characterized by 2 stages of evolution (acute, from two weeks to two months) and chronic (from several months to several years).
Symptoms of the acute phase of helminthiasis
The first signs of the disease may appear at different times (most often after 2-3 weeks, with ascariasis - after 2-3 days, and with filariasis, the incubation period can last 6-18 months).
In the acute stage of parasite invasion, the most characteristic symptom is an allergic reaction (antibodies are produced against antigens of migrating parasite larvae). Often, in people infected with worms, itchy rashes appear on the skin, with a tendency to a recurrent course, enlargement of regional lymph nodes, generalized or local edema, muscle and joint pain may occur. In addition, migration of the parasite's larvae can cause chest pain, coughing, choking attacks, irritated stools, nausea and vomiting.
At the same time, the acute phase of helminthiasis may be accompanied by more serious disorders (severe forms of pneumonia, hepatitis, allergic myocarditis, hepatosplenomegaly (enlarged liver and spleen), meningoencephalitis).
The number of eosinophils in the blood increases (eosinophilia) and the normal quantitative proportion between protein fractions is altered (dysproteinemia).
Signs of chronic helminthiasis
The symptomatology of the chronic phase depends directly on which organ is "inhabited" by the parasites, as well as its size and number play an important role.
Therefore, when parasitizing the intestines of isolated individuals, the disease can be asymptomatic (except in cases of infection by very large parasites). The characteristic signs of the chronic phase of intestinal helminthiasis are dyspeptic disorders. In children, asthenoneurotic and painful syndrome is more pronounced. With the massive invasion of roundworms, the development of intestinal obstruction, obstructive jaundice and pancreatitis is possible.
Consuming from the host's body all the substances necessary for its vital activity, helminths cause digestive disturbances, impaired absorption of vitamins, minerals, carbohydrates, proteins and fats. At the same time, the waste products of the worms inhibit normal intestinal microflora and reduce the body's immune forces.
In people suffering from helminthiasis, due to a weakened immune system and an intensified process of cell division (a consequence of the constant restoration of tissues damaged by parasites), the risk of malignant tumors increases significantly.
Types of helminths parasitizing the human body
The causative agents of human helminthiasis are 2 types of worms: round (nematodes) and flat (tapeworms and worms).
Roundworms
Pinworm
The parasites that cause enterobiasis are small cavity worms (up to 10 mm) with a gray-white color. The infection occurs through food (through the mouth). The reason for this is dirty hands. The parasite's eggs may be in the soil, in the wool of infected animals, unwashed vegetables and fruits, etc. At the same time, in enterobiasis, cases of autoinfection are frequent (mainly in children), resulting from scratches on the itchy areas and subsequent swallowing of eggs. Having become an adult, the parasitic worm in the lower sections of the upper and smaller sections of the colon.
Still in the larval phase, the moth begins to attack the host's body, producing enzymes that irritate the intestinal walls and lead to the development of an inflammatory process. Adult parasites attach to or penetrate the deepest layers of the intestinal mucosa, interrupting their integrity and contributing to the fixation of a secondary bacterial infection. In the case of perforation of the mesh of the wall of the small intestine, peritonitis may occur. In addition, due to irritation of the intestinal receptors, the motor and secretory functions of the gastrointestinal tract are interrupted, leading to the formation of gastroduodenitis, enteritis, etc. In childhood, long-term enterobiasis can cause nervous disorders and delay physical development.
Ascaris
Ascaris is a large fusiform parasite of red-yellow color, reaching up to 40 cm (females) and 15-25 cm (males) in adulthood. Without suction cups or other fixing devices, the roundworm is able to move independently towards the masses of food. The eggs laid by the female parasite are excreted along with the faeces.
Ascariasis infection occurs when ripe eggs are swallowed with water or vegetables and fruits not washed with soil particles. After eggs enter the intestines, mature larvae emerge from them. Then, penetrating the intestinal wall, they reach the heart through the bloodstream and, from there, reach the lungs. Through the pulmonary alveoli, the roundworm larva through the respiratory tract again enters the oral cavity. After repeatedly swallowing, the parasite reaches the small intestine, where it becomes an adult. The worm lives for 12 months, then dies and is excreted along with the faeces. In the intestines of a host, both one and several hundred individuals can live.
In the intestinal phase of its existence, roundworms, endowed with the ability to move in a spiral, can penetrate even the narrowest openings. This characteristic of the parasite often leads to the development of very serious complications (obstructive jaundice or pancreatitis). Allergens secreted by roundworms can cause severe allergic reactions. A large number of adults can cause intestinal obstruction, and worms that enter the respiratory tract can sometimes cause suffocation.
Vlasoglav
Vlasoglav, the causative agent of trichocephalosis, is a white helminth that parasites in the initial section of the large intestine and reaches a size of 4-5 cm. The parasite feeds on blood and tissues of the rectal mucosa.
Whipworm eggs deposited by the female in the intestinal walls come out with the feces. Its development occurs in the environment (ideally in the soil). Eggs with ripened parasite larvae enter the body through food, through dirty hands, with water or unwashed vegetables and fruits.
With a small number of worms, trichocephalosis is asymptomatic. In a severe phase (with massive invasion), the patient develops abdominal pain, develops severe diarrhea, sometimes accompanied by rectal prolapse. This condition is most often seen in debilitated children. With a moderate stage of trichocephalosis, the child's growth retardation is possible.
Trichinella
The causative agent of trichinosis is a small round helminth that reaches 2 to 5 mm in length. The infection occurs when eating undercooked meat (pork, bear meat, wild boar).
Penetrating the intestines, the larva of the parasite matures in 3-4 days until the state of a sexually mature individual. The worm's lifespan is 40 days, after which the parasite dies. When perforating the intestinal wall, the larvae enter the bloodstream and are transported to all organs of the human body, settling in the muscles. In this case, the respiratory and facial muscles, as well as the flexor muscles of the limbs, are the most affected.
In the first days after the invasion, patients complain of abdominal pain. Then, after about 2 weeks, the body temperature rises to 39-40 C, itchy rashes appear on the skin, develop muscle pain and the face swells. During this period, in case of massive infection, there is a significant risk of death. After about a month, the patient recovers. The parasite is encapsulated in a spiral form, after which it dies in two years.
Hookworm and nekator
These two parasites are similar in biological characteristics, as well as in diseases caused. In this regard, it is customary to combine them under a common name (hookworm). Worms, reaching lengths of 10-15 mm, parasitize in 12-p. intestine. It should be noted that this is one of the most common parasites, but, at the same time, rarely detected. Worm larvae enter the human body through the skin in contact with contaminated soil. In addition, as they enter the bloodstream, they, like roundworms, migrate to the lungs and then through the bronchi, along with sputum, to the digestive tract. Ankylostoma parasites in the intestine, adhering to the intestinal wall. The parasite, which feeds exclusively on blood, bites the blood vessels that penetrate the mucous membrane, injecting an anticoagulant component there. On average, an adult can absorb 0. 05-0. 35 ml of blood per day. Therefore, the most characteristic symptom of this helminthiasis is iron deficiency anemia, as well as a change in the proportion of protein fractions (dysproteinemia).
Flatworms
Wide ribbon
This is one of the largest helminths, reaching a length of 10-20 meters. The disease caused by this parasite is called diphyllobotriasis. The worm's development cycle begins with freshwater fish or crustaceans. The larva enters the human body, which is the final owner of the tapeworm, along with infected fish eggs or fillets. Reaching the small intestine, the parasite attaches itself to its wall and becomes a mature individual in 20-25 days.
Diphyllobotriasis occurs in the context of disorders of the digestive tract and anemia due to B12 deficiency.
Liver worm
The parasite that causes opistorchiasis is a flattened worm that reaches a length of 7-20 mm. It should be noted that more than 50% of cases of liver worm infection (also called cat worm) occur in the inhabitants of Russia. The parasite's larvae begin to develop after the eggs enter fresh water (from the snails that swallowed them). Then they penetrate the body of the fish (carp, crucian carp, golden, cockroach). Human infection occurs when eating contaminated fish meat that has not undergone sufficient heat treatment. The larva of the hepatic worm in the small intestine enters the bile ducts and the gallbladder, fixing itself there with the help of two suction cups.
In the acute phase of helminthiasis, the patient has pain in the upper abdomen, increased body temperature, development of nausea, muscle pain, diarrhea and skin rashes are possible. The chronic course of opistorchiasis is manifested by symptoms of hepatitis, inflammation of the bile ducts, cholecystitis, disorders of the digestive tract, nervous disorders, weakness and increased fatigue. The parasite leads to the development of irreversible changes and, even after its expulsion, the patient does not present chronic inflammatory processes and functional disorders.
Bovine and swine tapeworm
These parasites, almost identical in structure, reach a length of 5 to 6 meters. Infection with teniarosis and teniasis occurs due to the consumption of infected beef or pork by the Finns (one of the intermediate forms of helminthiasis). Viable Finns, presented in the form of whitish bubbles that reach 0. 5 cm in size, attach themselves to the wall of the human small intestine and become adults in 3 months. The tape parasite, which consists of more than 2, 000 segments, is constantly growing. In this case, the final segments, containing eggs, separate and move independently along the large intestine to the anus and then either crawl out of the anus or are released into the external environment along with the faeces. The most characteristic symptoms of helminthiasis are disorders of the digestive tract.
Echinococcus
For this parasite, a person is an intermediate host. The worm parasites the human body in the form of the Finns. The final owner of the echinococcus is a wolf, a dog or a cat.
The infection occurs by feeding through contact with animals and with environmental objects sown with Echinococcus eggs. After entering the intestine, the oncospheres (larvae with six hooks) develop from them. From the intestines, they enter the bloodstream and are transported throughout the body.
The "favorite" parasitic sites of the worm are the liver and lungs. Upon settling in these organs, the larva turns into a Finn (echinococcal cyst), which, gradually increasing in size, begins to destroy nearby tissues. Often, echinococcosis in the diagnostic process is confused with a tumor of benign or malignant origin. In addition to the mechanical impact (compression of organs and blood vessels), rupture of the echinococcal cyst sometimes occurs. This condition can cause toxic shock or the formation of several new cysts.
Alveococcus
This parasite, considered a type of echinococcus, is the cause of one of the most dangerous helminthiasis (alveococcosis), whose severity is similar to cirrhosis and liver cancer. Infection occurs when oncospheres (eggs with mature larvae) enter the intestine. There, the embryo emerges from the egg and, penetrating the intestinal walls, enters the bloodstream. In addition, with blood flow, the parasite spreads to all tissues and organs of the body (most often it is located in the liver). This is where the main stage of development in the larvae begins (a bubble with multiple chambers, the laurocyst forms). Each chamber contains the parasite's embryonic head, which continues to develop gradually. Laurocysts are very aggressive formations that grow constantly due to blisters that increase in size and also have the ability to grow to the liver, such as cancer metastases. Necrotic changes due to disturbances in the functioning of blood vessels undergo necrotic changes in the surrounding tissues. Spreading to nearby structures, the alveococcus forms fibrous nodules with inclusions of multi-American bubbles. This condition can last for several years and therefore requires mandatory surgical intervention.
Diagnosis of helminthiasis
The diagnosis of helminthic invasions includes the following activities:
- a complete history, helping to discover the possible causes of the infection;
- laboratory tests for feces, blood, intestinal 12p content, rectal and perianal mucus, muscle tissue, pulmonary expectoration, bile. Analysis can reveal parasite eggs, segments or fragments. At the same time, an increased content of eosinophils in the blood is also a sign of the presence of helminthiasis.
- in the diagnosis of diseases caused by larval phases or tissue parasites, serological studies are performed (ELISA, RSK, indirect agglutination reaction, immunofluorescence analysis, etc. ).
- ultrasound, computed tomography and endoscopic exams are prescribed to detect helminths that affect liver tissue.
Human worms: treatment
In the acute phase of a parasitic infection, the patient is prescribed detoxification and desensitization therapy. In severe cases of the disease (liver flukes, trichinosis), glucocorticoids are used according to medical instructions.
As specific therapy drugs, taking into account the nature of the pathogen, special anthelmintic chemotherapeutic agents are prescribed.
In parallel, the patient should take antihistamines and enterosorbents. The final stage of treatment includes the use of probiotics that normalize the intestinal microflora.
A special economy diet is also prescribed (foods must be digestible and low in fat).
During the anthelmintic therapy period, the patient must strictly observe personal hygiene (to avoid reinfection). At the same time, for many helminthiasis, all family members and people who are in constant contact with those infected must be treated.
Prevention of helminthiasis
- Maintenance of personal and public hygiene;
- Strict adherence to cooking technology;
- Regular examination and preventive treatment of pets;
- Careful washing of fresh vegetables, fruits and herbs;
- Proper handling of river fish;
- Avoid eating raw, slightly salted and dry fish.