To date, science knows about 280 types of worms that can grow and live in the human body, parasitizing various organs and tissues. The frequency of human infection with the worm depends on the climatic and socio-economic conditions of specific territories (in underdeveloped countries, especially in those located in the tropics and subtropics, the level of parasitic infections is much morehigher than in economically developed countries).
Means of human infection with helminths
- Biohelminthiasis (animal infection).
- Contagious helminthiasis (transmitted from person to person).
- Geohelminthiasis (diseases caused by parasites that go through one of their life cycles in the 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;
- Habitat of the worm (tissue parasites live in the thickness of soft tissues and the luminals live in the lumens of hollow organs). Some helminths in different phases have both luminal and tissue forms. As a rule, the larval and developing stages of worms cause more pronounced pathological changes.
In the absence of reinfection, the number of adult parasites in the human body does not increase. This feature 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 from 6 to 18 months).
In the acute stage of parasitic 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, prone to recurrent course, an increase in regional lymph nodes, generalized or local edema, muscle and joint pain may occur. In addition, migrating parasite larvae can cause chest pain, coughing, choking attacks, disturbed 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 ratio between protein fractions is disturbed (dysproteinemia).
Signs of chronic helminthiasis
The symptomatology of the chronic phase directly depends on the organ "inhabited" by the parasites, and their size and number play an important role.
Thus, when parasitizing in the intestines of isolated individuals, the disease may be asymptomatic (except for cases of infection with very large parasites). The characteristic signs of the chronic phase of intestinal helminthiasis are dyspeptic disorders. In children, the syndrome of asthenoneurosis and pain is more pronounced. With the massive invasion of roundworms, the development of intestinal obstruction, obstructive jaundice and pancreatitis is possible.
Consuming all the substances necessary for their vital activity from the host body, helminths cause digestive disorders, impaired absorption of vitamins, minerals, carbohydrates, proteins and fats. At the same time, the waste products of the worms inhibit the normal intestinal microflora and reduce the immune forces of the body.
In people with helminthiasis, due to a weakened immune system and an improved process of cell division (a consequence of the constant restoration of tissue damaged by parasites), the risk of malignant tumors increases significantly.
Types of helminths parasitizing in the human body
The agents responsible for human helminthiasis are 2 types of worms: round (nematodes) and flat (tapeworms and fluke).
Roundworms
pinworms
The parasites responsible for enterobiosis are small, thin-cavity worms (up to 10 mm) with a grayish-white coloration. The infection occurs food (through the mouth). The reason is dirty hands. The eggs of the parasite can be in the soil, on the wool of infected animals, unwashed vegetables and fruits, etc. At the same time, with enterobiosis, cases of self-infection are common (especially in children), resulting from the scratching of the itchy areas and the subsequent ingestion of eggs.
Pinworm larvae develop within two weeks in the digestive tract. As an adult, the worm parasitizes the lower and upper parts of the colon.
Even in the larval stage, pinworm begins to harm the body of its host, producing enzymes that irritate the intestinal walls and lead to the development of an inflammatory process. Adult parasites stick or penetrate the deeper layers of the intestinal mucosa, disrupting its integrity and contributing to the attachment of a secondary bacterial infection. If pinworms puncture the wall of the small intestine, peritonitis can develop. In addition, due to irritation of intestinal receptors, the motor and secretory functions of the gastrointestinal tract are disturbed, leading to the formation of gastroduodenitis, enteritis, etc. In childhood, long-term enterobiosis can cause nervous disorders and delayed physical development.
Ascaris
Ascaris is a large, fusiform red-yellow parasite, reaching 40 cm (females) and 15-25 cm (males) in adulthood. Without suction cups or other fasteners, the roundworm is able to move independently towards food masses. The eggs laid by the female of the parasite are excreted with the feces.
Ascariasis infection occurs when mature eggs are swallowed with water or unwashed vegetables and fruits containing soil particles. Once the eggs have entered the intestines, mature larvae emerge from them. Then, entering the intestinal wall, they reach the heart through the bloodstream and from there they enter the lungs. Through the pulmonary alveoli, the roundworm larva through the respiratory tract re-enters the oral cavity. After repeated swallowing, the parasite reaches the small intestine, where it turns into an adult. The worm lives for 12 months, then dies and is excreted with the feces. In the intestines of a host, one and several hundred individuals can live.
In the intestinal phase of their existence, roundworms, endowed with the ability of spiral movements, can penetrate even the narrowest openings. This feature of the parasite often leads to the development of quite serious complications (obstructive jaundice or pancreatitis). Allergens secreted by roundworms can cause severe allergic reactions. Large numbers of adults can cause intestinal obstruction, and the worms that enter the airways sometimes cause suffocation.
Vlasoglav
Vlasoglav, the causative agent of trichocephalosis, is a white helminth parasitizing in the initial section of the large intestine and reaching a size of 4 to 5 cm. The parasite feeds on blood and tissue in the rectal lining.
The whipworm eggs laid by the female on the intestinal walls come out with the feces. Their development takes place in the environment (optimally in the soil). Eggs containing the larvae of the ripened parasite 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 stage (with massive invasion) the patient develops abdominal pain, severe diarrhea develops, sometimes accompanied by rectal prolapse. This condition is most often seen in debilitated children. With a moderate phase of trichocephalosis, retarded growth of the child is possible.
Trichinella
The causative agent of trichinosis is a small, round helminth up to 2 to 5 mm in length. The infection occurs by eating poorly roasted meat (pork, bear meat, wild boar).
Entering the intestines, the larva of the parasite matures in 3-4 days to the state of a sexually mature individual. The lifespan of the worm is 40 days, after which the parasite dies. By piercing 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 most often 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, muscle pain develops, and the face swells. During this period, in case of massive infection, the risk of death is significant. After about a month, the patient recovers. The parasite is encapsulated in a spiral form, after which it dies within 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). The worms, reaching lengths of 10 to 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 quite rarely detected. Worm larvae enter the human body through the skin on contact with contaminated soil. In addition, entering the bloodstream, they, like roundworms, migrate to the lungs, and then, through the bronchi, along with expectorants, into the digestive tract. Parasitic hookworm in the intestine, attaching to the intestinal wall. The parasite, which feeds exclusively on blood, bites through the blood vessels that enter the mucous membrane, injecting them with an anticoagulant component. 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 ratio of protein fractions (dysproteinemia).
Flatworms
Large ribbon
It is one of the largest helminths, reaching a length of 10 to 20 meters. The disease caused by this parasite is called diphyllobothriasis. The worm's development cycle begins with freshwater fish or crustaceans. The larva enters the human body, which is the final owner of the broad tapeworm, with infected eggs or fish fillets. Reaching the small intestine, the parasite attaches to its wall and becomes a mature individual within 20 to 25 days.
Diphyllobothriasis occurs against the background of digestive tract disorders and vitamin B12 deficiency anemia.
Liver fluke
The parasite responsible for opisthorchiasis is a flatworm reaching a length of 7 to 20 mm. It is noteworthy that more than 50% of cases of infection with liver fluke (also called cat fluke) occur in the inhabitants of Russia. The larvae of the parasite begin to develop after the eggs have entered fresh water (from the snails that swallowed them). Then, they enter the body of fish (carp, crucian, sea bream, roach). Human infection occurs when eating contaminated fish meat that has not undergone sufficient heat treatment. The larva of the hepatic fluke of the small intestine enters the bile ducts and the gallbladder, attaching itself there with the help of two suction cups.
In the acute phase of helminthiasis, the patient has pain in the upper abdomen, body temperature rises, nausea develops, muscle pain, diarrhea and rash are possible. The chronic course of opisthorchiasis is manifested by symptoms of hepatitis, inflammation of the bile ducts, cholecystitis, digestive tract disorders, nervous disorders, weakness and increased fatigue. The parasite leads to the development of irreversible changes, and even after its expulsion, the patient does not experience chronic inflammatory processes and functional disorders.
Tapeworm in cattle and pork
These parasites, of almost identical structure, reach a length of 5 to 6 meters. Infection with teniarinhoses and tapeworm occurs due to the consumption of meat from cattle or pigs infected with Finns (one of the intermediate forms of helminthiasis). Viable Finns, presented as whitish bubbles up to 0. 5 cm, attach to the wall of the human small intestine and develop into an adult within 3 months. The band parasite, made up of more than 2000 segments, is constantly growing. In this case, the end segments, containing eggs, break off and move independently along the large intestine to the anus, then crawl out of the anus or are released into the external environment with the materials. feces. The most characteristic symptoms of helminthiasis are disturbance of the digestive tract.
Echinococcus
For this parasite, a person is an intermediate host. The worm parasitizes the human body in the form of the Finns. The ultimate owner of the echinococcus is a wolf, dog, or cat.
Infection occurs through food contact with animals and environmental objects seeded with Echinococcus eggs. After entering the intestine, oncospheres (six-hooked larvae) develop from them. From the intestines, they enter the bloodstream and are carried throughout the body.
The "favorite" parasitic sites of the worm are the liver and lungs. Settling in these organs, the larva turns into Finn (echinococcal cyst), which, gradually increasing in size, begins to destroy nearby tissues. Often echinococcosis in the process of diagnosis is mistaken for 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 helminthiases (alveococcosis), the severity of which is similar to cirrhosis and cancer of the liver. Infection occurs when oncospheres (eggs with mature larvae) enter the intestine. There the embryo leaves the egg and, penetrating the intestinal walls, enters the bloodstream. In addition, with the blood flow, the parasite spreads to all tissues and organs of the body (most often it is localized in the liver). This is where the main stage of development in larvae begins (a bubble with several chambers, the laurocyst is formed). Each chamber contains the embryonic head of the parasite, which continues to grow gradually. Laurocysts are very aggressive formations that are constantly growing due to the enlargement of the bubbles and also have the ability to grow in the liver like cancer metastases. Necrotic changes due to disturbances in the functioning of blood vessels undergo necrotic changes in nearby tissues. Extending to neighboring structures, the alveococcus forms fibrous nodes with inclusions of multicameral bubbles. This condition can last for several years and therefore requires mandatory surgery.
Diagnosis of helminthiasis
The diagnosis of helminthic invasions includes the following activities:
- a thorough history, helping to uncover possible causes of the infection
- laboratory tests of feces, blood, 12p intestinal contents, rectal and perianal mucus, muscle tissue, pulmonary sputum, bile. Analysis may reveal eggs, segments or fragments of the parasites. At the same time, an increased content of eosinophils in the blood is also a sign of the presence of helminthiasis.
- when diagnosing diseases caused by larval stages or tissue parasites, serological studies are performed (ELISA, RSK, indirect agglutination reaction, immunofluorescence analysis, etc. ).
- Ultrasound, CT and endoscopic examinations are prescribed to detect helminths affecting 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 trematodes, trichinosis), glucocorticoids are used according to medical indications.
As specific therapy drugs, taking into account the nature of the pathogen, special anthelmintic chemotherapeutic agents are prescribed.
In parallel, the patient is recommended to take antihistamines and enterosorbents. The last stage of treatment includes the use of probiotics that normalize the intestinal microflora.
A special savings diet is also prescribed (food should be digestible and low in fat).
During the period of anthelmintic treatment, the patient is obliged to strictly observe personal hygiene (in order to avoid re-infection). At the same time, for many helminthiasis, all family members and those in constant contact with those infected must undergo treatment.
Prevention of helminthiasis
- Maintain personal and public hygiene;
- Strict adherence to cooking technology;
- Regular examination and preventive treatment of pets;
- Thorough washing of fresh vegetables, fruits and herbs;
- Correct handling of river fish;
- Avoid consuming raw, lightly salted and dried fish.