Helminths

Helminthiases, or diseases caused by helminths, are among the most common in humans. According to rough estimates by experts from the World Health Organization, one in four people on the planet is infected with one or the other helminths. And it is not surprising, because you can get this infection almost anywhere in the world. Doctors equate the incidence of helminthiasis with the spread of influenza and ARVI.

Doctors estimate the scale of worm infection in our country at 270 cases per 100, 000 inhabitants, but the real incidence, according to experts, is several times higher. This is due to the fact that often a person does not even realize that an uninvited guest has settled on his body. If helminths do not manifest themselves in any way, the disease can remain undiagnosed for decades.

All about helminths

Worms, helminths or parasitic worms?

This vast group of living things has several names at the same time. First of all, we are talking about parasites, that is, living organisms that live at the expense of others. In addition, we are talking about endoparasites, that is, they live inside another organism, in its tissues and organs. Finally, we are talking about worm-like creatures, which are ideally adapted to live for a long time in the body of an infected animal and reproduce effectively.

Consequently, helminths are parasitic worms. The same term "helminths" was once introduced by Hippocrates. Among the people, these nasty creatures are also called worms, from the ancient Greek word, which simply means parasitic worm.

So, speaking of helminths, we will make no mistake, calling them worms or parasitic worms. And if we talk about helminthiasis, these diseases can also be called "parasitic infections".

A variety of helminths in humans.

In total, scientists know about 287 types of helminths that can parasitize humans. In our country, only 65 species have been identified, and only 24 species are among the most common.

Helminths in humans live throughout the body and each species has its own preferences.

Basically, worms prefer the gastrointestinal tract and mainly the small intestine, in which roundworms, pinworms, three varieties of tapeworms, broad tapeworms, hookworms, etc. can be found. Vlasoglav alone occupies the large intestine.

In the liver, more precisely in its bile ducts, as well as in the gallbladder, flukes, opisthorchis, etc. can be found. The pulmonary trematode settles in the lungs. Trichinella affects the muscles. The adult pig tapeworm lives in the small intestine and its larvae (cysticercus) can be found in the eyes and central nervous system. Schistosomes (helminths of the tropics) prefer the veins of the gastrointestinal tract and the genitourinary system.

Filariae are generally ubiquitous (they can be found in the lymphatic system and in closed body cavities) in the retroperitoneal space, in the pericardial sac, and their larvae are generally found in the blood or on the skin.

Types of helminths that live in humans

Helminths, the types of which are most interesting to doctors, are divided into two main types: flat and round (nematodes). The classification is based on the cross section of the worm's body: in roundworms it is shaped like a circle, and in flatworms it flattens in the direction from the conditional back to the conditional abdomen. Flatworms are further divided into two classes: trematodes (flukes) and tapeworms (cestodes).

• Nematodes. Most nematodes are inhabitants of the human intestine. This group includes roundworms, pinworms, Trichinella, whipworms, etc. , very different from each other in size, from a couple of millimeters to 1. 5 meters. Everyone has their own well-developed digestive system. Nematodes have males and females. It is not difficult to distinguish between them in adults: females are usually twice as large, and in addition, in males, the "tail" is twisted towards the "abdomen".
• Trematodes. The body of flukes resembles a leaf or lancet in shape and cannot be compared in size to other helminths: these are small worms, from a few millimeters to 3. 5-5. 5 cm long. Unlike roundworms, flukes have a pair of suction cups on their mouth and abdomen. His digestive system is in diapers. An important part of the species in this group are hermaphrodites, that is, they combine the characteristics of both sexes. The exception is schistosomes, which have males and females.
• Cestodes. Cestodes are worms, which are a long ribbon fragmented into short segments, at one end of which is a hooked head and suction cups. These worms live exclusively in the small intestine; his whole body does not fit in any other organ. And this is not surprising, because the length of tapeworms can reach 10-11 meters. They do not need a digestive system at all, since they absorb everything they need from the food that a person eats. All tapeworms are hermaphrodites.

The organism in which the helminths live in the larval stage is called the intermediate host (they can be animals, fish, mollusks and, of course, humans), and the carrier of adult forms is called the final host.

Depending on whether a certain type of worms has a developmental stage in the body of an intermediate host, biohelminths and soil-transmitted helminths are also referred to.

• The soil-transmitted helminths do not have such a stage. The eggs of the worms fall to the ground, where they wait until, by the will of fate, they are introduced into the body of the future owner. The soil-transmitted helminths include whipworms, roundworms, hookworms, etc.
• Biohelminths have such a stage and there may be several hosts. Examples include Trichinella, tapeworms, schistosomes, all flatworms, etc.

Some scientists now, by the transmission mechanism, distinguish a third group of worms: contagious helminths, which include roundworms (soil-transmitted helminths) and dwarf tapeworms (biohelminths). These parasites are transmitted by contact with an infected person.

In addition, depending on which hosts play a key role in the life of helminths, anthroponoses and zoonoses are isolated.

• The first category includes helminthiasis, in which a person is a mandatory stage in his life cycle: ascariasis, enterobiasis, etc.
• Zoonoses include helminthiases, the causative agents of which can successfully exist without a person, but at the same time our species is also susceptible to them, and if an infection occurs, the worms will not interfere with life and prosperity. This category includes opisthorchiasis, diphyllobothriasis, etc.

How does helminth infection occur?

Most often, people become infected with worms, so to speak, orally, that is, by swallowing helminth eggs. The most striking example is pinworms, the eggs of which a child can collect in a litter box (a form of infection from household contact). The alimentary route (through food) is characteristic of roundworms, through contaminated vegetables or fruits and flukes that enter the body when contaminated but poorly thermally processed seafood or meats are eaten, etc.

However, food is not the only route of infection with helminths. Eggs can enter the human body through inhalation of dust. And hookworms and schistosomes enter the body through the skin, and they are called contagious worms, and the route of infection is percutaneous. And since the schistosome can be contracted while swimming in a pond, this route of infection is also called aquatic.

In the tropics, the filamentous plant lives, it is also wuchereria, which spreads with the help of a mosquito bite. And this is a transmission route of vector-borne infections.

Helminth infection can also occur through contact with animals: infected dogs and cats. People usually get roundworms (toxocar, etc. ) and tapeworms from animals. Pets, in the process of licking, carry helminth eggs through their fur. A person who has stroked such an animal and has not washed his hands immediately afterwards runs the risk of injecting an infection into his mouth. Another option for worm infestation is to clean the litter box without gloves.

How do helminths affect the body?

Mechanical impact

This category includes any action of helminths in which the integrity of the host's tissues is violated. For example, adult helminths with hooks and suction cups fix themselves with their help, while damaging the gastrointestinal mucosa. As a result, tissue erosion develops in the area of localization of the worm, ulcers form, and the nutritional processes of the mucous membrane are disrupted, which can even lead to its death (necrosis).

As they move through the body, the so-called migratory larvae can also cause bleeding and inflammation in damaged areas, making it easier for them to penetrate deep into the tissues. And helminths in the intestines often provoke the development of appendicitis, intestinal obstruction, and even its rupture.

Finally, the cysticercus, which has entered the brain and is actively growing there, squeezes the tissues, which can lead to the death of a person.

Host malnutrition

First, the helminths themselves "steal" their host, consuming the food they have eaten. Second, some human helminths feed on blood; this is what hookworms and whipworms do, or take substances necessary for hematopoiesis. Therefore, against the background of a parasitic infection, anemia may develop.

With a long-term chronic infection with helminths, which absorb metabolically valuable nutrients, a protein-calorie deficiency is diagnosed.

Poisoning of the human body with helminth toxins.

The metabolic products of whipworm and tapeworm destroy red blood cells, and roundworm secretions cause capillary expansion and, as a result, bleeding.

Some parasitic worms begin to pose greater danger after death, releasing substances with necrotic and hemotoxic properties.

Helminth protein allergy.

Helminths are foreign organisms to us, therefore our body perceives many proteins secreted by them (in the process of vital activity or after death) as a potential danger and can consider them as antigens. In the course of sensitization to these antigens, antibodies are formed: immunoglobulins IgE and IgG-4. These antibodies, when they come into contact with mast cells, basophils and eosinophils, cause their destruction. At the same time, there is a release of substances that trigger allergic reactions (allergy mediators): histamine, serotonin, heparin, etc.

Suppression of the body's defenses.

The negative effect of helminths on the body can be indirect. Tapeworms, located, as mentioned above, in the small intestine, can cause a decrease in gastric acidity. And this significantly reduces the protection against the penetration of pathogenic bacteria into the body.

Many helminths have immunosuppressive abilities, that is, they suppress the body's defenses, ensuring a comfortable existence for a long time. This is an evolutionary adaptation acquired by them in the course of adaptation to a narrowly defined host circle. But the suppression of the human immune system leads to increased vulnerability to other infections and diseases.

Cancer risks

Some chronic helminthiases significantly increase the likelihood of cancer. Parasites in the course of their vital activity destroy tissues and organs, and thus provoke the development of malignant tumors in this place. Cancer often develops against the background of opisthorchiasis, schistosomiasis, clonorchiasis, etc.

Phases of the course of helminthiasis.

What are the signs of helminthiasis? Once the worms have entered the body, the symptoms of infection will depend on the stage of the disease.

During helminthiasis, there are 4 main phases:

• Acute (early) phase of helminthiasis. At this stage, the causative agent of infection enters the human body, which leads to the sensitization of the body to helminth proteins. The first symptoms of helminths appear 2 to 4 weeks after infection. Usually, during this period, allergic-type reactions develop: itchy skin rashes, conjunctivitis, cough, swollen lymph nodes, inflammatory processes in the joints, analyzes show an increased concentration of eosinophils, etc.
• Latent phase (latent). At this stage, the helminth develops to an adult state and is finally determined with a permanent dwelling place, after which the helminth passes into a chronic stage.
• Chronic (late) phase. At this stage, adult helminths actively reproduce, producing tens and hundreds of thousands of eggs and larvae, which enter the external environment or spread to other organs of the body. Helminths in children can provoke muscle cramps, seizures - epileptic, hysterical, etc. Doctors note that all these signs of helminthiasis are non-specific and are similar to the symptoms of dozens of other diseases, making them impossible to diagnose. More precisely, there are several helminths, the symptoms of which are very characteristic, but even they must be verified by a series of tests.
• Exodus phase. This term means the complete recovery of the patient or the disability of her in the context of the complications of helminthiasis. These include malignant tumors in opisthorchiasis and schistosomiasis, liver cirrhosis, etc.

Helminths: symptoms of infection

How the helminth invasion (the invasion of helminths into your body) will affect the human body is determined by many factors: the method of penetration, the extent of the infection, the duration of the disease and the lifespan of the helminth, thecharacteristics of its cycle of nutrition and development.

In general, doctors distinguish the following symptoms of helminth infection, in the presence of which you need to consult a doctor and undergo an examination:

• frequent periodic nausea and vomiting, abdominal pain;
• frequent allergies;
• sleep disorders, chronic fatigue, irritability;
• itching in the anal area;
• frequent urinary tract infections;
• chronic gastrointestinal diseases, dysbiosis;
• symptoms of chronic intoxication of the body: frequent colds, blue circles under the eyes, paleness, enlarged lymph nodes;
• vulvovaginitis;
• an elevated level of eosinophils in the results of a blood test;
• delayed growth and weight.

The question arises: if helminths have settled in the body, will the symptoms of infection be visible immediately or only after some time? Are there helminths that are difficult to detect signs of infection? Doctors note that with a non-intensive invasion, the first symptoms of helminthiasis can appear in one to two months and after a few years. That is, during this time, no signs of helminth infection will be visible.

Manifestations of helminth infection in children.

Helminths are more common in children than in adults. This is explained by a lack of hygiene skills, as well as close contact with the environment, which can be a source of helminth eggs. Such an environment can be a sandbox on a playground, beds in a grandmother's country house, someone else's toy played by an infected child, etc.

What complaints are most frequently reported when children are infected with intestinal nematodes?

• gastrointestinal tract dysfunction - 75% of children;
• allergic reactions - 71%;
• sleep disorders: 54%;
• appetite disorders - 44%;
• pain in the abdomen - 40%;
• itching in the anal area - 36%.

Less frequently, against the background of helminth infection, children developed immune disorders (19%) and bruxism, that is, teeth grinding (16%). It is a paradox, but the population generally considers these two symptoms to be signs of helminths.

Diagnosis of helminthiasis

What are the tests for helminths?

It should be understood that helminth analysis alone is not sufficient. None of the existing methods for detecting parasitic worms on its own can serve as a basis for making a definitive diagnosis. According to doctors, in some cases, a positive result can only be achieved for the 8th to 10th time! There may be many reasons for this: the females lay eggs at different intervals that do not coincide with the sampling times, the biomaterial samples turned out to be empty, because they were taken from the wrong place, the disease was in such a phase that it was determined bythe methods that were selected almost impossible, etc.

The most common types of tests for helminths are stool study for helminth eggs, perianal scraping, analysis of duodenal contents, analysis of biomaterials from the patient's lungs, blood tests for helminths, etc.

Less often, urine is required for diagnosis (schistosomiasis of the genitourinary system, enterobiasis), a helminth study of the patient's muscles (trichinosis) is carried out with a sample of material by a biopsy method.

How is stool tested for helminth eggs?

For the analysis of helminths, 50 g of the patient's stool is enough (this is about 1 tablespoon). Today in the pharmacy you can buy a special clean container for tests, where you will need to collect feces for helminth eggs. It is best to deliver the sample to the laboratory the same day (for strongyloidosis and hookworms, no later than 4 hours after collection). If necessary, you can store a helminth stool sample for no more than a day at a temperature of 0-4 ° C, it is absolutely impossible to freeze it. In principle, it is possible to use special preservatives that allow the samples to be stored for several months.

Perianal scraping: analysis of helminth eggs

Perianal scraping is used to diagnose helminthiasis such as enterobiasis, taeniasis, teniarinchiasis, etc. Unlike the stool test for helminths, scraping material is collected from the skin around the anus using a cotton swab, wooden spatula, glass eye sticks, or tape. The procedure for collecting material for the analysis of helminth eggs is carried out early in the morning and the patient should not wash either at night or in the morning.

An important point: even a repeated analysis of helminths in this way does not guarantee the reliability of the result in case of enterobiasis. Female pinworms lay eggs at regular intervals, and if you don't catch the "right time, " you can be sure there are no eggs, no worms.

Analysis of duodenal content (bile)

The collection of bile is done with an empty stomach tube. Since this method is invasive (unlike methods such as helminth egg stool, urine collection, and perianal scraping), it is prescribed only for strict indications when there is a reasonable suspicion of a specific helminthiasis. Bile is examined for strongyloids and hookworm larvae, and individual portions of bile are also analyzed for the presence of helminth eggs that live in the pancreas and hepatic ducts.

Blood tests for helminths

In addition to the above methods, there are also so-called serological methods for the diagnosis of helminthiasis. In this case, a blood test is carried out for helminths, more precisely, to detect antibodies against them.

The main current serological method is the enzyme-linked immunosorbent assay (ELISA), which is distinguished by its high specificity and the highest sensitivity (90%) among all other methods. That is, it allows you to determine quite precisely what kind of helminths a person is infected with and allows you to detect them, even if there are very few of them. The reliability of ELISA is 60%. ELISA is extremely relevant for the detection of the so-called tissue helminthiasis, in which the worms parasitize inside the organs and tissues of the patient (trichinosis, toxocariasis).

Instrumental methods of diagnosis of helminths.

It is far from always possible to detect helminths using the above methods of laboratory diagnosis, including the use of immunological methods of analysis. Some parasitic worms have a dense capsule that is resistant to external influences. They can also hide in tissues that are protected to some degree from inflammatory reactions in the body, such as the spinal cord. Certain types of worms have their own means of protection: anti-enzymes. Worms that can reproduce exchange genetic information sexually. Given the speed of their reproduction and renewal of generations, it is not surprising that, over time, these helminths become less vulnerable to the means of detecting and treating parasitic infections.

If the analysis of feces for helminths, blood and other methods did not give any effect, in this case, such parasites can be detected using the instrumental diagnostic methods: X-ray, ultrasound, computed tomography, etc. , tissues of the liver and spleen, enlarged lymph nodes in the latter, finally, in some cases, echinococci, large clumps, tangles of intestinal worms, the parasites themselves can be seen.

Helminthiasis treatment

Traditional medicine, through trial and error, discovered a number of plants with anthelmintic properties: aspen, pumpkin, chamomile, tansy, male fern, etc. Later, in the days of scientific pharmaceuticals, scientists isolated active substances from them that actually gave an anthelmintic. effect:

• cucurbitin (pumpkin seeds);
• annual artemisinin wormwood);
• ascaridol (ragweed);
• santonin (citrine wormwood);
• thymol (thyme);
• pelletierin (pomegranate root);
• carvacrol (oregano, thyme, bergamot);
• Diospirol (persimmon);
• arecolin (arec palm);
• pyrethrins (Dalmatian chamomile);
• tremulacin (aspen);
• nicotine (tobacco) and its anabazine isomer (tobacco and leafless corral);
• emetine (emetic root).

And today, a considerable part of anthelmintic drugs contains the same active substances that once provided the anthelmintic effect to decoctions and tinctures.

conclusions

• Helminthiasis is one of the most common diseases in the world. Anyone in your environment with a 100% probability has people and animals infected with helminths.
• But if the number of people in the body is small, and the body itself is generally healthy, then the disease can be asymptomatic for many years, without manifesting itself in any way.
• Even a regular medical examination every 3 years or testing once a year does not guarantee that a person really does not have helminths.
• The signs of worms in the body can be very similar to the symptoms of other diseases. Therefore, if the treatment of intestinal diseases and other similar pathologies for some reason does not help persistently, you should think about testing for helminths.
• Based on the results of a helminth test, the diagnosis of helminthiasis is not made, as both false positive and false negative results are possible. You should not try to submit to an examination independently at random; it is better to consult a doctor: based on the totality of the symptoms, nutritional data and travel data, he will select tests that will allow to find out exactly whether a person has helminths or not.
• You can not independently prescribe helminth pills. A remedy for worms can have contraindications for a particular patient and cause serious harm if used incorrectly.