To date, science knows about 280 types of worms that can develop and live in the human body, parasitizing in various organs and tissues. The frequency of human worm infection depends on the climatic and socio-economic conditions of specific territories (in underdeveloped countries, especially in those located in tropical and subtropical areas, the level of parasitic infections is much higher than in economically developed countries).
Ways of human helminth infection
- Biohelminthiasis (animal infection).
- Contagious helminthiasis (transmitted from person to person).
- Geohelminthiasis (diseases caused by parasites that carry out one of their life cycles in the earth).
Factors influencing the manifestations of helminthiasis
- The way the parasite enters the body;
- The degree of adaptation of the helminth to the human body;
- Population density (number) of parasitic individuals;
- The habitat of the worm (tissue parasites live in the thickness of soft tissues and luminal parasites live in the lumens of hollow organs). Some helminths in different stages have both luminal and tissue forms. The larval and developmental 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 feature significantly distinguishes helminth invasions from diseases caused by bacteria, viruses, fungi and protozoa.
Worms in humans: symptoms
Helminthiasis is a disease characterized by 2 stages of the course (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 can 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 phase of parasitic invasion, the most characteristic symptom is an allergic reaction (antibodies against antigens of migrating parasite larvae are produced). Often in people infected with worms, itchy rashes appear, prone to a recurrent course, increased regional lymph nodes, generalized or local edema, muscle and joint pain. Additionally, the migration of parasitic larvae can cause chest pains, coughs, choking attacks, upset stools, nausea and vomiting.
At the same time, the acute phase of helminthiasis can be accompanied by more serious ailments (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 of protein fractions is disturbed (dysproteinemia).
Signs of chronic helminthiasis
The symptomatology of the chronic phase directly depends on which organ is "inhabited" by the parasites, as well as their size and number play an important role.
So, when parasitizing in the intestines of individuals, the disease can be asymptomatic (except in cases of infection with very large parasites). The characteristic signs of the chronic phase of intestinal helminthiasis are dyspeptic disorders. In children, asthenonurotic and pain syndrome is more pronounced. With a massive invasion of roundworms, the development of intestinal obstruction, obstructive jaundice and pancreatitis is possible.
By consuming all the substances necessary for their vital activity from the host's body, helminths cause digestive disorders, reduced absorption of vitamins, minerals, carbohydrates, proteins and fats. At the same time, the waste products of worms inhibit the normal intestinal microflora and reduce the body's immune forces.
In people suffering from helminthiasis, due to a weakened immune system and an enhanced cell division process (a consequence of the constant restoration of tissues damaged by parasites), the risk of malignant tumors increases significantly.
Types of helminth parasites in the human body
The causative agents of human helminthiasis are 2 types of worms: round (roundworms) and flat (tapeworms and flukes).
nematodes
Pinworm
Parasites that cause enterobiasis are small, thin-cavity worms (up to 10 mm) with a greyish-white color. Infection occurs alimentary (through the mouth). The reason for this is dirty hands. The eggs of the parasite can be in the soil, on the wool of infected animals, unwashed fruits and vegetables, etc. At the same time, with enterobiasis, cases of self-infection are frequent (especially in children), resulting from the itchy areas and subsequent swallowing of the eggs. 
The pinworm larva develops within two weeks in the digestive tract. Having transformed into an adult, the parasitic worm in the lower sections of the small and upper sections of the colon.
Even in the larval stage, pinworms begin to damage the body of its host, producing enzymes that irritate the intestinal walls and lead to the development of an inflammatory process. Adult parasites attach themselves to or penetrate the deeper layers of the intestinal mucosa, disrupting its integrity and contributing to the attachment of a secondary bacterial infection. In case of pinworm perforation of the wall of the small intestine, peritonitis can develop. In addition, due to irritation of the intestinal receptors, the motor and secretory functions of the gastrointestinal tract are disrupted, leading to the formation of gastroduodenitis, enteritis, etc. In childhood, long-term enterobiasis can cause nervous disorders and delay in physical development.
Ascaris
Ascaris is a large spindle-shaped parasite of red-yellow color, reaching 40 cm (females) and 15-25 cm (males) in adulthood. Without suction cups or other fasteners, the nematode is able to autonomously move towards the food masses. The eggs laid by the female of the parasite are excreted along with the feces.
Ascariasis infection occurs when mature eggs are ingested with water or unwashed vegetables and fruits with soil particles. After the eggs have entered the intestine, mature larvae emerge from them. Then, penetrating the intestinal wall, they reach the heart through the bloodstream and from there enter the lungs. Through the pulmonary alveoli, the nematode larva through the respiratory tract enters the oral cavity again. After repeated swallowing, the parasite reaches the small intestine, where it develops into an adult. The worm lives for 12 months, then dies and is excreted along with the feces. Both one and several hundred individuals can live in the intestine of a host.
In the intestinal phase of their existence, nematodes, endowed with the ability to spiral movements, can penetrate even the narrowest openings. This feature of the parasite often leads to the development of rather serious complications (obstructive jaundice or pancreatitis). The allergens secreted by roundworms can cause severe allergic reactions. A large number of adults can cause intestinal obstruction, and worms entering the respiratory tract 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.
The whipworm eggs laid by the female on the intestinal walls come out together with the feces. Their development occurs in the environment (optimally in the soil). The eggs with the larvae of the parasite matured in them enter the body via food, through dirty hands, with water or unwashed fruits and vegetables.
With a small number of worms, whipworm 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 stage of trichocephalosis, growth retardation of a child is possible.
Trichinella
The causative agent of trichinosis is a small round helminth reaching 2-5 mm in length. Infection occurs when eating poorly roasted meat (pork, bear meat, wild boar).
Penetrating the intestine, the parasite larva matures in 3-4 days to the state of a sexually mature individual. The life span 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 aches develop, 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 shape, after which it dies within two years.
Hookworm and nekator
These two parasites are similar in biological characteristics, as well as in the diseases they cause. In this regard, it is customary to combine them under one common name (hookworm). The worms, which reach 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, detected quite rarely. Worm larvae enter the human body through the skin upon contact with contaminated soil. In addition, entering the bloodstream, like nematodes, they migrate to the lungs and then, through the bronchi, together with the expectorant sputum, into the digestive tract. Hookworm parasites in the intestine, attaching itself to the intestinal wall. The parasite, which feeds exclusively on blood, bites the blood vessels that penetrate the mucosa, injecting them with an anticoagulant component. On average, an adult can absorb 0. 05-0. 35ml 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).
Flat worms
Wide ribbon
This is one of the largest helminths, reaching a length of 10-20 meters. The disease caused by this parasite is called diphyllobothriasis. The worm development cycle begins with freshwater fish or crustaceans. The larva enters the human body, which is the final owner of the broad tapeworm, along with infected eggs or fish fillets. Reaching the small intestine, the parasite attaches itself to its wall and grows to a mature individual within 20-25 days.
Diphylobothriasis occurs against the background of digestive tract disorders and vitamin B12 deficiency anemia.
Liver fluke
The parasite that causes opisthorchiasis is a flat worm that reaches a length of 7-20 mm. It should be noted that more than 50% of cases of liver fluke infection (also called cat fluke) occur in the inhabitants of Russia. The parasite 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, bream, beetle). Human infection occurs when contaminated fish meat is eaten that has not undergone sufficient heat treatment. The larva of the liver fluke from the small intestine penetrates the bile ducts and gallbladder, fixing itself there with the help of two suckers.
In the acute phase of helminthiasis, the patient presents pain in the upper abdomen, increased body temperature, nausea, muscle aches, diarrhea and skin rashes 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 undergo chronic inflammatory processes and functional disorders.
Bovine and porcine tapeworm
These parasites, almost identical in structure, reach a length of 5-6 meters. Teniarinosis and teniasis infection occurs due to the consumption of meat from cattle or pigs infected by Finns (one of the intermediate forms of helminthiasis). Viable Finns, presented in the form of whitish bubbles reaching 0. 5 cm in size, attach themselves to the wall of the human small intestine and turn into an adult in 3 months. The tape parasite, consisting of more than 2000 segments, is constantly growing. In this case, the terminal segments, containing the 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 along with the feces. The most characteristic symptoms of helminthiasis are disruption 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. 
Infection occurs through food contact with animals and environmental objects sown with Echinococcus eggs. After entering the intestine, oncospheres (six-hooked larvae) develop. From the intestine, they enter the bloodstream and are transported throughout the body.
The worm's "favorite" parasitic sites are the liver and lungs. Settling in these organs, the larva turns into a Finn (echinococcal cyst), which, gradually increasing in size, begins to destroy neighboring tissues. Often, echinococcosis in the diagnostic process is mistaken for a tumor of benign or malignant origin. In addition to mechanical impact (squeezing of organs and blood vessels), rupture of the echinococcal cyst sometimes occurs. This condition can cause toxic shock or the formation of multiple new cysts.
Alveococcus
This parasite, considered a type of echinococcus, is the cause of one of the most dangerous helminthiases (alveococcosis), similar in severity to cirrhosis and liver cancer. 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 bloodstream, the parasite spreads to all tissues and organs of the body (most often it is localized in the liver). It is there that the main stage of development in the larvae begins (a multi-chamber bubble forms, the laurocyst is formed). Each chamber contains the parasite's embryonic head, which continues to develop gradually. Laurocysts are very aggressive formations that grow steadily 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. Spreading to neighboring structures, the alveococcus forms fibrous nodes with inclusions of multi-chamber bubbles. This condition can last for several years and therefore requires mandatory surgery.
Diagnosis of helminthiasis
Diagnosis of helminthic invasions includes the following activities:
- a complete history analysis, helping to discover the possible causes of infection;
- laboratory tests on feces, blood, intestinal contents 12p, rectal and perianal mucus, muscle tissue, lung sputum, bile. The analysis can reveal eggs, segments or fragments of parasites. At the same time, an increase in the content of eosinophils in the blood is also a signal of the presence of helminthiasis.
- when diagnosing diseases caused by larval stages or tissue parasites, serological studies are carried out (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 flukes, 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 final stage of treatment involves the use of probiotics that normalize the intestinal microflora.
A moderate special diet is also prescribed (food must be digestible and low in fat).
During the period of anthelmintic therapy, the patient is required to strictly observe personal hygiene (in order to avoid re-infection). At the same time, for many helminthiases, all family members and people who are in constant contact with the 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 the consumption of raw, lightly salted and dried fish.