To date, science knows about 280 species of worms that can develop and live in the human body, parasitizing in various organs and tissues. The frequency of human worm infestation depends on the climatic and socio-economic conditions of certain territories (in underdeveloped countries, especially those in tropical and subtropical zones, the level of parasitic infections is much higher than in economically developed countries).
Ways of infecting humans with helminths
- Biohelminthiasis (animal infection).
- Infectious helminthiases (transmitted from person to person).
- Geohelminthiasis (diseases caused by parasites that spend one of their life cycles on earth).
Factors influencing the manifestations of helminthiasis
- The way the parasite enters the body;
- Degree of adaptation of helminths to the human body;
- Population density (number) of parasitic individuals;
- Worm habitat (tissue parasites live in the thickness of soft tissues, and luminal in the lumens of hollow organs). Some helminths have different luminal and tissue forms at different stages. Larvae and stages of worm development, as a rule, cause more pronounced pathological changes.
In the absence of re-infection, 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 phases 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 may appear at different times (usually after 2-3 weeks, in ascariasis - after 2-3 days, and in 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 are produced to the antigens of the larvae of migrating parasites). Often, people infected with worms develop itchy rashes on the skin, prone to recurrent flow, enlarged regional lymph nodes, generalized or local edema, muscle and joint pain may occur. Also, migrating parasite larvae can cause chest pain, cough, choking attacks, upset 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 relationship between protein fractions (dysproteinemia) is disturbed.
Signs of chronic helminthiosis
The symptomatology of the chronic phase directly depends on which organ is “inhabited” by parasites, as well as their size and number play an important role.
Thus, when parasitizing in the intestines of individuals, the disease may be asymptomatic (except in cases of infection by very large parasites). Characteristic signs of the chronic phase of intestinal helminthiasis are dyspeptic disorders. In children, asthenoneurotic and pain syndrome are 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 organism, helminths cause digestive disorders, impaired absorption of vitamins, minerals, carbohydrates, proteins and fats. At the same time, worm waste products inhibit the normal intestinal microflora and reduce the body's immune system.
In people who suffer from helminthiasis, due to a weakened immune system and an intensified process of cell division (a consequence of constant regeneration of tissues damaged by parasites), the risk of malignant tumors increases significantly.
Types of helminths that parasitize the human body
The causes of human helminthiasis are 2 types of worms: roundworms (nematodes) and flatworms (tapeworms and flukes).
Roundworms
Pinworm
The parasites that cause enterobiasis are small (up to 10 mm) thin worms of the gray-white cavity. Infection occurs through food (through the mouth). The reason for that is dirty hands. Parasite eggs can be in the ground, on the wool of infected animals, unwashed vegetables and fruits, etc. At the same time, in enterobiasis, there are frequent cases of self-infection (especially in children), which is the result of scratching the itchy area and subsequent swallowing of eggs.
The pinworm larva develops in the digestive tract within two weeks. Turning into an adult, the worm parasitizes in the lower parts of the small and upper part of the large intestine.
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 cling to or penetrate deeper layers of the intestinal mucosa, disrupting its integrity and contributing to the binding of secondary bacterial infection. In case of perforation of pinworms in the wall of the small intestine, peritonitis may develop. Also, due to irritation of intestinal receptors, the motor and secretory function of the gastrointestinal tract is disturbed, which leads to the formation of gastroduodenitis, enteritis, etc. In childhood, long-term enterobiasis can cause nervous disorders and delays in physical development.
Askaris
Ascaris is a large red-yellow spindle parasite that reaches 40 cm (females) and 15-25 cm (males) in adulthood. Without dinghies or other fastening devices, the roundworm can move independently towards food masses. Eggs laid by a female parasite are excreted along with the feces.
Ascariasis infection occurs when mature eggs are swallowed with water or unwashed vegetables and fruits with soil particles. Once the eggs enter the intestines, mature larvae emerge from them. Then, penetrating the intestinal wall, they reach the heart with the blood, and from there they enter the lungs. Through the pulmonary alveoli, the larva of the roundworm re-enters the oral cavity through the respiratory tract. After repeated ingestion, the parasite reaches the small intestine, where it develops into an adult. The worm lives for 12 months and then dies and is excreted along with the feces. One and several hundred individuals can live in the intestines of one host.
In the intestinal phase of their existence, roundworms, endowed with the ability of spiral movements, can penetrate even the narrowest openings. This characteristic of the parasite often leads to the development of quite serious complications (obstructive jaundice or pancreatitis). Allergens secreted by roundworms can cause serious allergic reactions. A large number of adults can cause intestinal obstruction, and worms that enter the respiratory tract sometimes cause suffocation.
Vlasoglav
Vlasoglav, the cause of trichocephaly, is a white helminth that parasitizes in the initial part of the colon and reaches a size of 4-5 cm. The parasite feeds on blood and tissues of the rectal mucosa.
Bee eggs laid by the female on the intestinal walls come out along with the feces. Their development takes place in the environment (optimally in the soil). Eggs with mature parasite larvae enter the body through food, dirty hands, water or unwashed vegetables and fruits.
With a small number of worms, trichocephaly is asymptomatic. In the severe phase (with massive invasion), the patient develops abdominal pain, severe diarrhea develops, sometimes accompanied by rectal prolapse. This condition is most commonly seen in debilitated children. With a moderate phase of trichocephaly, a developmental delay in the child is possible.
Trichinella
The cause of trichinosis is a small round helminth that reaches a length of 2-5 mm. Infection occurs when eating poorly roasted meat (pork, bear meat, wild boar).
Penetrating into 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 transmitted to all organs of the human body, settling in the muscles. In this case, the respiratory and facial muscles are most often affected, as well as the flexor muscles of the limbs.
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 the case of a mass infection, there is a significant risk of death. After about a month, the patient recovers. The parasite encapsulates in a spiral shape, after which it dies within two years.
Hookworm and some
These two parasites are similar in biological characteristics as well as in diseases caused. In this regard, it is common to combine them under a common name (ankylosis). Worms, which reach a length of 10-15 mm, parasitize in 12 p. intestines. It should be noted that this is one of the most common, but at the same time very rarely detected parasites. Worm larvae enter the human body through the skin after contact with contaminated soil. Further, entering the bloodstream, they migrate like worms into the lungs and then, through the bronchi, together with the expectorant sputum, into the digestive tract. Hookworm parasitizes in the intestines, attaching to the intestinal wall. The parasite, which feeds exclusively on blood, bites blood vessels that penetrate the mucosa, injecting an anticoagulant component there. An adult on average can absorb 0, 05-0, 35 ml of blood per day. Therefore, the most characteristic symptom of this helminthiasis is anemia due to iron deficiency, as well as changes in the ratio 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 development cycle begins with freshwater fish or crabs. The larva enters the human body, which is the ultimate owner of the broad tapeworm, along with eggs or infected fish fillets. Reaching the small intestine, the parasite attaches to its wall and grows in a mature individual within 20-25 days.
Diphyllobotriasis occurs in the background of disorders of the digestive tract and anemia with B12 deficiency.
Liver fluff
The parasite that causes opisthorchiasis is a flatworm that reaches a length of 7-20 mm. It should be noted that more than 50% of cases of hepatitis B flu infection (also called feline flu) occur in the population of Russia. The larvae of the parasite begin to develop after the eggs enter the 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 eaten. The liver fluke larva from the small intestine penetrates the bile ducts and the gallbladder, fixing itself there with the help of two vacuum cups.
In the acute phase of helminthiasis, the patient has pain in the upper abdomen, body temperature rises, nausea develops, muscle pain, diarrhea and skin rash are possible. The chronic course of opisthorchiasis 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 expulsion the patient does not go through chronic inflammatory processes and functional disorders.
Beef and pork tapeworm
These parasites, almost identical in structure, reach a length of 5-6 meters. Infection with teniarinhoza and teniaza occurs due to the consumption of beef or pork infected with Finns (one of the middle forms of helminthiasis). Sustainable Finns, presented in the form of whitish bubbles the size of 0, 5 cm, attach to the wall of the small intestine of man and in 3 months turn into an adult. The tapeworm parasite, which consists of more than 2, 000 segments, is constantly growing. In this case, the end segments containing the eggs break and move independently along the colon 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 disorders of the digestive tract.
Echinococcus
For this parasite, the person is the middle host. The worm parasitizes on the human body in the form of Finns. The final owner of an echinococcus is a wolf, a dog or a cat. 
Infection occurs through food through contact with animals and objects from the environment with Echinococcus eggs. After entering the intestine, oncospheres (larvae with six hips) develop from them. They enter the bloodstream from the intestines and are transmitted throughout the body.
The "favorite" parasitic sites of worms are the liver and lungs. By settling in these organs, the larva turns into a Finca (echinococcal cyst), which, gradually increasing in size, begins to destroy nearby tissues. Echinococcosis is often mistaken for a tumor of benign or malignant origin in the diagnostic process. In addition to mechanical impact (constriction of organs and blood vessels), echinococcal cysts sometimes rupture. This condition can cause toxic shock or the formation of multiple new cysts.
Alveokoki
This parasite, which is considered a type of echinococcus, is the cause of one of the most dangerous helminthiasis (alveococcosis), which is 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. Further, through the bloodstream, the parasite spreads to all tissues and organs of the body (it is most often localized in the liver). There begins the main stage of development in the larvae (a multichambered bubble is formed, a laurocyst is formed). 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 vesicles, and also have the ability to grow into the liver, like cancer metastases. Necrotic changes due to vascular dysfunction undergo necrotic changes in nearby tissues. Spreading to nearby structures, the alveococcus forms fibrous nodules with inclusions of multidirectional bubbles. This condition can last for several years and therefore requires mandatory surgical intervention.
Diagnosis of helminthiasis
Diagnosis of helminthic invasions includes the following activities:
- thorough history taking, helping to identify possible causes of infection;
- laboratory tests of feces, blood, intestinal contents 12p, rectal and perianal mucus, muscle tissue, lung sputum, bile. Analysis may reveal eggs, segments, or fragments of the parasite. At the same time, the increased content of eosinophils in the blood is also a signal of the presence of helminthiasis.
- when diseases caused by larval stages or tissue parasites are diagnosed, 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 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.
Special anthelmintic chemotherapeutic agents are prescribed as specific therapy drugs, taking into account the nature of the pathogen.In parallel, the patient is recommended to take antihistamines and enterosorbents. The last phase of treatment involves the use of probiotics that normalize the intestinal microflora.
A special frugal diet is also prescribed (food should be digestible and low in fat).
During the period of anthelmintic therapy, 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 people who are in constant contact with the infected must undergo treatment.
Prevention of helminthiasis
- Maintaining 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 handling of river fish;
- Avoid eating raw, lightly salted and dried fish.