Helminths

Helminthiases, or diseases caused by helminths, are among the most common in humans. According to rough estimates of experts from the World Health Organization, every fourth person on the planet is infected with one or another helminth. And it is not surprising, because you can catch 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 infection with worms in our country as 270 cases per 100 thousand of the population, but the real incidence, according to experts, is several times higher. This is due to the fact that often a person does not even notice that an uninvited guest has settled in his body. If the helminths do not manifest themselves in any way, then the disease may remain undiagnosed for decades.

All about helminths

Parasitic worms, helminths or worms?

This vast group of living beings has several names at once. 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, living inside another organism - in its tissues and organs. Finally, we are talking about worm-like creatures that are ideally adapted to live long in the body of an infected animal and reproduce effectively.

Accordingly, helminths are parasitic worms. The very term "helminths" was once introduced by Hippocrates. Among the people, these unpleasant creatures are also called worms - from the ancient Greek word, just meaning a parasitic worm.

So, speaking about helminths, we will not be mistaken, calling them worms or parasitic worms. And if we are talking 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 on 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 you can find ascaris, pinworms, three varieties of tapeworms, broad tapeworm, hookworm, etc. Vlasoglav single-handedly 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 lung fluke settles in the lungs. Trichinella affects muscles. Adult pork tapeworm lives in the small intestine, and its larvae (cysticercus) can be found in the eyes and central nervous system. Schistosomes (helminths from 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 usually found in the blood or in 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 body of the worm: in round worms it is in the form of a circle, and in flat worms it is flattened in the direction from the conditional back to the conditional abdomen. Flatworms are further divided into two classes: flukes (trematodes) 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. They all have their own well-developed digestive system. Nematodes have both males and females. It is not difficult to distinguish 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 trematodes resembles a leaf or a lancet in shape and cannot be compared with other helminths in size: these are small worms, from a few millimeters to 3. 5-5. 5 cm long. Unlike roundworms, trematodes have a pair of suckers in the mouth and abdomen. Their digestive system is in its infancy. A significant part of the species from this group are hermaphrodites, that is, they combine the characteristics of both sexes. The exception is schistosomes, which have both males and females.
• Cestodes. Cestodes are worms, which are a long tape fragmented into short segments, at one end of which there is a head with hooks and suckers. These worms live exclusively in the small intestine - their entire body does not fit into 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, as they absorb everything they need from the food that a person eats. All tapeworms are hermaphrodites.

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

Depending on whether a given type of worms has a stage of development in the body of an intermediate host, they also speak of bio- and geohelminthiasis.

• Geohelminths do not have such a stage. The eggs of the worms fall into the soil, where they wait until, by the will of fate, they are brought into the body of the future owner. Geohelminths 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 pinworms (geohelminths) and dwarf tapeworms (biohelminths). These parasites are spread 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 an obligatory stage in their 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 infection does occur, then this will not prevent the worms from living and prospering. This category includes opisthorchiasis, diphyllobothriasis, etc.

How does helminth infection occur?

Most often, people become infected with worms, so to speak, orally, that is, swallowing helminth eggs. The most striking example is pinworms, the eggs of which a child can pick up in a sandbox (a contact-household way of spreading infection). The alimentary path (through food) is characteristic of roundworms - through contaminated vegetables or fruits and trematodes that enter the body when eating contaminated but poorly thermally processed seafood or meat, 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 schistosoma can be picked up 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 vector-borne route of infection transmission.

Infection with helminths can also occur through contact with animals - infected cats and dogs. Usually, people get roundworms (toxocar, etc. ) and tapeworms from animals. Pets, in the process of licking, carry helminth eggs through their fur. A person, having stroked such an animal and not washing his hands immediately after that, risks 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 actions of helminths in which there is a violation of the integrity of the host's tissues. 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 are formed, and the nutritional processes of the mucous membrane are disrupted, which can even lead to its death (necrosis).

Moving through the body, the so-called migratory larvae can also cause hemorrhages and inflammation in the damaged areas - this makes 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 "rob" their host, consuming the food they have eaten. Secondly, some human helminths feed on blood themselves - this is what hookworms and whipworms do, or they take away substances necessary for hematopoiesis. Therefore, against the background of a parasitic infection, anemia may develop.

With prolonged chronic infection with helminths, which absorb metabolically valuable nutrients, protein-caloric deficiency is diagnosed.

Poisoning the human body with helminth toxins

The metabolic products of the whipworm and tapeworm destroy erythrocytes, and ascaris secretions cause capillary expansion and, as a result, hemorrhages.

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

Allergy to helminth proteins

Helminths are organisms that are alien 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 may consider them as antigens. In the course of sensitization to these antigens, antibodies are formed - immunoglobulins IgE and IgG-4. These antibodies, when in 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, thereby 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 circle of hosts. But suppression of the human immune system leads to increased vulnerability to other infections and diseases.

Cancer risks

Some chronic helminthiasis significantly increase the likelihood of getting cancer. In the course of their vital activity, parasites destroy tissues and organs and thereby 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? After the worms have entered the body, the symptoms of infection will depend on the phase of the disease.

During helminthiasis, there are 4 main phases:

• Acute (early) phase of helminthiasis. At this stage, the causative agent of the infection enters the human body, which leads to sensitization of the body to the proteins of the helminth. The first symptoms of helminths appear 2-4 weeks after infection. Usually during this period, allergic-like reactions develop - itchy skin rashes, conjunctivitis, cough, swollen lymph nodes, inflammatory processes in the joints, analyzes show an increased concentration of eosinophils, etc.
• Latent (latent) phase. At this stage, the helminth develops to an adult state and is finally determined with a place of permanent habitation, after which the helminthiasis 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 not specific and are similar to the symptoms of dozens of other diseases, so it is impossible to diagnose them. More precisely, there are several helminths, the symptoms of which are very characteristic, but even they should be checked using a number of tests.
• Exodus phase. This term means either complete recovery of the patient, or his disability against the background of complications of helminthiasis. These include malignant tumors in opisthorchiasis and schistosomiasis, liver cirrhosis, etc.

Helminths: symptoms of infection

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

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

• periodic frequent 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, pallor, enlarged lymph nodes;
• vulvovaginitis;
• an increased 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 a while? Are there helminths that are difficult to detect signs of infection? Doctors point out that with a non-intensive invasion, the first symptoms of helminthiasis can appear in a month, or two, and after a few years. That is, during this time, no signs of infection with helminths 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 in a playground, beds in a grandmother's dacha, someone else's toy played by an infected child, etc.

What complaints are most often recorded when children are infected with intestinal nematodes:

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

Less often, against the background of infection with helminths, children developed immunity disorders (19%) and bruxism, that is, teeth grinding (16%). It is a paradox, but these two symptoms are generally considered by the population to be signs of helminths.

Diagnostics of helminthiasis

What are the tests for helminths?

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

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

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

How are feces tested for helminth eggs?

For the analysis for helminths, 50 g of the patient's feces 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 better to send the sample to the laboratory on the same day (for strongyloidosis and ankylostomiasis - no later than 4 hours after collection). If necessary, store a stool sample for helminths for no more than a day at a temperature of 0 to 4 ° C, it is absolutely impossible to freeze it. In principle, it is possible to use special preservatives that allow samples to be stored for up to several months.

Perianal scraping - analysis for helminth eggs

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

An important point: even a repeated analysis for 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 do not catch the "right moment", then you can remain confident that there are no eggs - there are no worms.

Analysis of duodenal contents (bile)

Collection of bile is carried out with a probe on an empty stomach. Since this method is invasive (unlike methods such as feces for helminth eggs, 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 strongyloides and hookworm larvae, and individual portions of bile are also analyzed for the presence of helminth eggs that live in the pancreas and liver ducts.

Blood test 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 for antibodies to them.

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

Instrumental methods of diagnostics of helminths

It is far from always possible to detect helminths using the above methods of laboratory diagnostics, including using 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 to some extent protected from inflammatory reactions of the body - such is the spinal cord. Certain types of worms have their own means of protection - antienzymes. Those worms that can reproduce sexually exchange genetic information. Given the speed of their reproduction and renewal of generations, it is not surprising that such helminths over time become less vulnerable to means of detecting and treating parasitic infections.

If the analysis of feces for helminths, blood and other methods did not give an effect, in this case, such parasites can be detected using the methods of instrumental diagnostics - X-ray, ultrasound, computed tomography, etc. Indirect signs of infection with worms include an increase in the spleen (hepatosplenomegaly), heterogeneitytissues of the liver and spleen, an increase in the lymph nodes in the latter, finally, in some cases - echinococcus, large clusters-tangles of intestinal worms - you can see the parasites themselves.

Treatment of helminthiasis

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);
• artemisinin annual wormwood);
• ascaridol (ambrosia);
• santonin (citrine wormwood);
• thymol (thyme);
• pelletierin (pomegranate root);
• carvacrol (oregano, thyme, bergamot);
• diospirol (persimmon);
• arecoline (arec palm);
• pyrethrins (dalmatian chamomile);
• tremulacin (aspen);
• nicotine (tobacco) and its isomer anabazine (tobacco and leafless barnyard);
• 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. Any person in his environment with a 100% probability has people and animals infected with helminths.
• But if the number of individuals 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 taking tests once a year does not guarantee that a person really does not have helminths.
• Signs of worms in the body can be very similar to symptoms of other diseases. Therefore, if the treatment of intestinal diseases and other similar pathologies for some reason persistently does not help, you should think about taking tests for helminths.
• According to the results of one analysis for helminths, the diagnosis of helminthiasis is not made, since both false-positive and false-negative results are possible. You should not try to independently undergo an examination at random - it is better to consult a doctor: based on the totality of symptoms, nutritional data and travel data, he will select tests that will make it possible to find out exactly whether a person has helminths or not.
• You can not independently prescribe yourself pills for helminths. A remedy for worms can have contraindications for a particular patient and cause serious harm if used incorrectly.