To date, science knows about 280 types of worms that can develop and live in the human body, parasitizing 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 the tropics and subtropics, the level of parasitic infections is much higher than in economically developed countries).
Forms of human infection with helminths
- Biohelminthiasis (infection of animals).
- Contagious Helminthiases (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 the helminth to the human body;
- Population density (number) of parasitic individuals;
- The worm's habitat (tissue parasites live in the thickness of soft tissues and luminal ones live in the lumens of hollow organs). Some helminths in different phases have 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 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 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 from 6 to18 months).
In the acute stage of parasitic invasion, the most characteristic symptom is an allergic reaction (antibodies are produced against the antigens of the migratory parasite larvae). Often in people infected with worms, itchy rashes appear on the skin, prone to a recurrent course, increased regional lymph nodes, generalized or local edema, muscle and joint pain. Additionally, migrating parasite larvae can cause chest pains, coughing, choking attacks, feces, nausea, and vomiting.
At the same time, the acute phase of helminthiasis can be accompanied by more serious disorders (severe forms of pneumonia, hepatitis, allergic myocarditis, hepatosplenomegaly (enlargement of the liver and spleen), meningoencephalitis).
The number of eosinophils in the blood increases (eosinophilia) and the normal quantitative ratio between protein fractions is altered (dysproteinemia).
Signs of chronic helminthiasis
The symptoms of the chronic phase directly depend on which organ is "inhabited" by parasites, as well as their size and number play an important role.
So, by parasitizing in the intestines of individual 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, asthenoneurotic and pain syndrome is more pronounced. With the massive invasion of pinworms, 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, 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 body's immune forces.
In people suffering from helminthiasis, due to a weakened immune system and an enhanced 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 that parasitize in the human body
The causative agents of human helminthiasis are 2 types of worms: round (nematodes) and flat (tapeworms and trematodes).
Roundworms
Roundworm
The parasites that cause enterobiasis are small worms (up to 10 mm) with a thin cavity with a grayish-white coloration. The infection occurs by food (through the mouth). The reason for this is dirty hands. The parasite's eggs can be in the ground, in the wool of infected animals, unwashed vegetables and fruits, etc. At the same time, with enterobiasis, cases of autoinfection are frequent (especially in children), as a consequence of scratching of the itchy areas and subsequent ingestion of eggs. 
Pinworm larvae develop in two weeks in the digestive tract. Having become an adult, the worm parasitizes in the lower sections of the small and upper sections of the colon.
Even in the larval stage, the roundworm begins 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 adhere to or penetrate the deeper layers of the intestinal mucosa, altering its integrity and contributing to the adhesion of a secondary bacterial infection. In the case of pinworm perforation of the wall of the small intestine, peritonitis can develop. Also, 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 delayed physical development.
Ascaris
Ascaris is a large red-yellow spindle-shaped parasite that reaches 40 cm (females) and 15-25 cm (males) in adulthood. Without suction cups or other holding devices, the roundworm can move independently towards the food masses. The eggs that the female of the parasite lays are excreted along with the feces.
Ascariasis infection occurs when mature eggs are swallowed with water or unwashed vegetables and fruits with dirt particles are ingested. After the eggs enter the intestines, mature larvae emerge from them. Then, penetrating the intestinal wall, they reach the heart through the bloodstream and from there they enter the lungs. Through the pulmonary alveoli, the roundworm larvae through the respiratory tract again enter the oral cavity. After repeated ingestion, the parasite reaches the small intestine, where it becomes an adult. The worm lives for 12 months, then dies and is excreted with feces. In the intestines of a host, as many as one to several hundred individuals can live.
In the intestinal phase of their existence, roundworms, endowed with the ability to perform spiral movements, can penetrate even the narrowest of openings. This feature of the parasite often leads to the development of quite serious complications (obstructive jaundice or pancreatitis). The allergens secreted by pinworms can cause severe allergic reactions. Large numbers of adults can cause intestinal obstruction, and worms that enter the respiratory tract sometimes cause suffocation.
Vlasoglav
Vlasoglav, the causative agent of whipworm, is a white helminth that parasitizes in the initial section of the large intestine and reaches a size of 4-5 cm. The parasite feeds on the blood and tissues of the rectal mucosa.
Whipworm eggs laid by the female on the intestinal walls are released along with the feces. Its development takes place in the environment (optimally in the soil). The eggs with the mature parasite larvae in them enter the body through food, through dirty hands, with water, or with unwashed vegetables and fruits.
With a small number of worms, whipworms are asymptomatic. In a severe stage (with massive invasion), the patient develops abdominal pain, severe diarrhea develops, sometimes accompanied by rectal prolapse. This condition is seen most often in debilitated children. With a moderate phase of whipworm, a child may be stunted.
Trichinella
The causative agent of trichinosis is a small round helminth that reaches 2 to 5 mm in length. The infection occurs by eating poorly roasted meat (pork, bear meat, wild boar).
Upon entering the intestines, the larvae of the parasite mature in 3-4 days to the stage of a sexually mature individual. The worm's lifespan 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 extremities, are the most affected.
In the first days after 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 the case of a massive infection, there is a significant risk of death. After about a month, the patient recovers. The parasite is encapsulated in a spiral fashion, after which it dies within two years.
Hookworm and nekator
These two parasites are similar in biological characteristics, as well as in caused diseases. In this sense, it is common to combine them under a common name (hookworm). The worms, reaching lengths of 10-15 mm, parasitize at 12-p. intestine. It should be noted that this is one of the most common parasites, but, at the same time, very rarely detected. Worm larvae enter the human body through the skin when they come into contact with contaminated soil. Also, upon entering the bloodstream, like roundworms, they migrate to the lungs and then, through the bronchi, together with the expectorant sputum, to the digestive tract. The hookworm parasitizes in the intestine and attaches itself to the intestinal wall. The parasite, which feeds exclusively on blood, bites through blood vessels that penetrate the mucosa, injecting there 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 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 diphyllobothriasis. The worm development cycle begins with freshwater fish or crustaceans. The larvae enter the human body, which is the ultimate owner of the broad tapeworm, along with infected eggs or fish fillets. Upon reaching the small intestine, the parasite attaches to its wall and grows into a mature individual in 20-25 days.
Diphyllobothriasis occurs in the context of digestive tract disorders and 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 infection with the liver parasite (also called the cat parasite) occur in the inhabitants of Russia. The larvae of the parasite 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, cockroach). Human infection occurs when contaminated fish meat that has not undergone sufficient heat treatment is ingested. The larvae of the liver fluke of the small intestine penetrate the bile ducts and the gallbladder, fixing 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 aches, diarrhea, and skin rashes may occur. The chronic course of opisthorchiasis is manifested by symptoms of hepatitis, inflammation of the bile ducts, cholecystitis, disturbances in 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 suffer from chronic inflammatory processes and functional disorders.
Bovine and swine tapeworms
These parasites, of almost identical structure, reach a length of 5-6 meters. Infection with teniarinhoses and taeniasis is caused by the consumption of beef or pork infected by the Finns (one of the intermediate forms of helminthiasis). Viable Finns, presented in the form of whitish bubbles reaching a size of 0. 5 cm, adhere to the wall of the human small intestine and become adults within 3 months. The ribbon parasite, which consists of more than 2000 segments, is constantly growing. In this case, the terminal segments, which contain eggs, are shed and move independently along the large intestine to the anus, and then either exit the anus or are released into the external environment along with the feces. The most characteristic symptom of helminthiasis is the alteration of the digestive tract.
Echinococcus
For this parasite, a person is an intermediate host. The worm parasitizes the human body in the form of Finns. The final owner of the echinococcus is a wolf, dog or cat. 
Infection occurs in food through contact with animals and environmental objects planted with Echinococcus eggs. After entering the intestine, oncospheres (six-hooked larvae) develop from them. From the intestines, they enter the bloodstream and are transported throughout the body.
The worm's "favorite" parasite sites are the liver and lungs. When settling in these organs, the larva turns into a Finn (echinococcal cyst) that, gradually increasing in size, begins to destroy nearby tissues. Often, echinococcosis in the diagnostic process is mistaken for a tumor of benign or malignant origin. In addition to mechanical impact (compression of organs and blood vessels), echinococcal cyst rupture 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 helminth infections (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 blood flow, 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 larvae begins (a multi-chambered bubble, laurocysts, forms). Each chamber contains the embryonic head of the parasite, which continues to develop gradually. Laurocysts are very aggressive formations that are constantly growing due to the enlargement of the bubbles and also have the ability to grow towards the liver, like cancer metastases. Necrotic changes due to alterations in the functioning of blood vessels undergo necrotic changes in nearby tissues. When spreading to nearby structures, the alveococcus forms fibrous nodules with inclusions of multicameral 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 medical history to help discover the possible causes of the infection;
- laboratory tests of stool, blood, intestinal contents 12p, rectal and perianal mucus, muscle tissue, lung sputum, bile. Analysis may 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.
- when diagnosing diseases caused by larval stages or tissue parasites, serological studies (ELISA, RSK, indirect agglutination reaction, immunofluorescence analysis, etc. ) are performed.
- 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.
At the same time, the patient is recommended to take antihistamines and enterosorbents. The final stage of treatment includes the use of probiotics that normalize the intestinal microflora.
A moderate diet is also prescribed (food should be digestible and low in fat).
During the period of anthelmintic therapy, the patient must strictly observe personal hygiene (to avoid reinfection). At the same time, for many helminthiases, all family members and people who are in constant contact with those infected must undergo treatment.
Helminthiasis Prevention
- 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;
- Proper management of river fish;
- Avoid eating raw, slightly salted and dry fish.