Helminths

Helminthiasis or diseases caused by helminths are among the most common among humans. According to rough estimates by experts from the World Health Organization, every fourth person on the planet is infected with one or another helminth. And it's not surprising, because you can catch this infection almost anywhere in the world. Doctors equate the frequency of helminthiasis with the spread of influenza and ARVI.

Doctors estimate the scale of worm infection in our country as 270 cases per 100 thousand of the population, but the real frequency, 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 in any way, then the disease can remain undiagnosed for decades.

Everything about helminths

Parasitic worms, helminths or worms?

This huge 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 in another organism - in its tissues and organs. Finally, we are talking about worm-like creatures, which are ideally adapted to live long in the body of an infected animal and to reproduce efficiently.

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

So, speaking of helminths, we will not be mistaken in calling them worms or parasitic worms. And if we talk about helminthiasis, these diseases can also be called "parasitic infections".

Variety of helminths in humans

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

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

In general, worms prefer the gastrointestinal tract and mainly the small intestine, where you can find roundworms, pinworms, three varieties of tapeworms, broad tapeworms, hookworms and more. Vlasoglav occupies the colon alone.

In the liver, more precisely in its bile ducts, as well as in the gallbladder, flukes, opisthorchiasis and others can be found. Pulmonary methyl is found in the lungs. Trichinella affects the muscles. Adult porcine 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 genitourinary system.

Filariae are usually 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, whose species 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 in the form of a circle, and in flatworms it is flattened in the direction from the conditional back to the conditional abdomen. Further, flatworms are divided into two classes: flukes (trematodes) and tapeworms (cestodes).

• Nematodes. Most nematodes inhabit the human intestine. This group includes roundworms, pinworms, Trichinella, whips and more. Very different from each other in size - from a few 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 "belly".
• Trematodes. The body of trematodes resembles a leaf or lancet in shape and cannot be compared in size to other helminths: these are small worms, a few millimeters long to 3, 5-5, 5 cm. Unlike roundworms, trematodes have a pair of shoots in the mouth and abdomen. Their digestive system is in its infancy. A significant part of the species in this group are hermaphrodites, ie they combine the characteristics of both sexes. Exceptions are schistosomes, which have both men and women.
• Cestodes. Cestodes are worms that are a long strip, 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 whole body does not fit into any other organ. And this is not surprising, since the length of tapeworms can reach 10-11 meters. They do not need a digestive system at all, as they absorb everything necessary 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 (these can be animals, fish, mollusks and, of course, humans), and the carrier of adult forms is called the final host.

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

• 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 bull worms, roundworms, hookworms, and more.
• Biohelminths have such a stage and there may be several hosts. Examples include Trichinella, tapeworm, schistosomes, all flatworms, and more.

Now, according to the mechanism of transmission, some scientists distinguish a third group of worms - infectious helminths, which include pinworms (geohelminths) and dwarf tapeworms (biohelminths). These parasites 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 a mandatory stage of his life cycle: ascariasis, enterobiosis and others.
• Zoonoses include helminthiasis, the causative agents of which can successfully exist without humans, but at the same time our species is also susceptible to them, and if an infection does occur, then the worms will not interfere with life and prosperity. This category includes opisthorchiasis, diphyllobotriasis and others.

How does a helminth infection occur?

Most often, people become infected with worms, so to speak, orally, that is, by ingesting helminth eggs. The most striking example is the pinworms, whose eggs the child can take in the sandbox (a way to spread the infection in the household). The food route (through food) is characteristic of roundworms - through contaminated vegetables or fruits and trematodes that enter the body when eating contaminated but poorly cooked seafood or meat and more.

However, food is not the only way to become infected with helminths. Eggs can enter the human body by inhaling dust. And hookworms and schistosomes enter the body through the skin - and they are called contagious worms, and the route of infection is through the skin. And because the schistosome can be caught while swimming in a pond, this route of infection is also called aqueous.

In the tropics, the filamentous plant also lives, it is a wuchereria, which is spread by mosquito bites. And this is a vector route of transmission.

Infection with helminths can also occur through contact with animals - infected cats and dogs. Usually people get roundworms (toxocara, etc. ) and tapeworms from animals. Pets, in the process of licking, carry helminth eggs through their fur. A person who petted such an animal and did not wash his hands immediately afterwards risks injecting an infection into his mouth. Another option for worm infestation is to clean the waste box without gloves.

How do helminths affect the body?

Mechanical impact

This category includes any action of helminths that disrupts the integrity of host tissues. For example, adult helminths with hooks and suction cups are fixed 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 mucosa are disrupted, which can even lead to its death (necrosis).

Moving through the body, so-called migrating larvae can also cause bleeding and inflammation in the damaged areas - this facilitates their penetration deep into the tissues. And helminths in the intestine 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 death.

Malnutrition of the hosts

First, the helminths themselves "rob" their host by consuming the food they have eaten. Second, some human helminths feed on blood on their own - this is done by hookworms and whips, or by taking the substances needed for hematopoiesis. to develop anemia.

Prolonged chronic infection with helminths, which absorb metabolically valuable nutrients, is diagnosed with protein-calorie deficiency.

Poisoning of the human body with helminth toxins

The metabolic products of whip and tapeworm destroy erythrocytes, and roundworm secretions cause capillaries to dilate and hemorrhage as a result.

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

Allergy to helminth proteins

Helminths are alien organisms to us, so our body perceives many proteins secreted by them (in the process of life 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 in contact with mast cells, basophils and eosinophils, cause their destruction. At the same time, a substance is released that causes allergic reactions (allergy mediators) - histamine, serotonin, heparin and others.

Suppression of the body's defenses

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

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

Risk of cancer

Some chronic helminthiasis significantly increases 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, clonorchosis and others.

Phases of helminthiasis

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

There are 4 main phases during helminthiasis:

• 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 helminth proteins. The first symptoms of helminths appear 2-4 weeks after infection. Usually during this period allergic reactions develop - itchy skin rashes, conjunctivitis, cough, swollen lymph nodes, inflammatory processes in the joints, tests show increased concentrations of eosinophils and others.
• Latent (latent) phase. At this stage, the helminth develops into an adult condition and is finally determined by the place of permanent residence, after which the helminthiasis becomes chronic.
• Chronic (late) phase. At this stage, adult helminths actively reproduce, producing tens and hundreds of thousands of eggs and larvae that enter the environment or spread to other organs of the body. Helminths in children can provoke muscle cramps, seizures - epileptic, hysterical and more. 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. Specifically, there are several helminths, the symptoms of which are very characteristic, but even they need to be checked with the help of a number of tests.
• Output 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 and others.

Helminths: symptoms of infection

How the helminth infestation (helminth invasion in his body) will affect the human body is determined by many factors: the method of penetration, the degree of infection, the duration of the disease and life expectancy of the helminth, the characteristics of its feeding cycle and development.

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, paleness, enlarged lymph nodes;
• vulvovaginitis;
• increased levels of eosinophils in blood test results;
• slow growth and weight.

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

Manifestations of helminth infection in children

Helminths are more common in children than in adults. This is explained by the 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 dacha, someone else's toy, played by an infected child, and so on.

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

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

Less often, against the background of helminth infection, children develop immune disorders (19%) and bruxism, ie grinding of teeth (16%). It is a paradox, but these two symptoms are usually considered by the population to be signs of helminths.

Diagnosis of helminthiasis

What are the helminth tests?

It should be understood that the analysis of helminths alone is not sufficient. None of the existing methods for detecting parasitic worms alone can serve as a basis for a definitive diagnosis. According to doctors, in some cases a positive result can be achieved only for the 8-10th time! The reasons for this can be many: 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 in the wrong place, the disease was in such a phase that it was determined bymethods that were chosen almost impossible, etc.

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

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

How are helminth egg stools tested?

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

Perianal scraping - analysis for helminth eggs

Perianal scraping is used to diagnose helminthiasis such as enterobiosis, teniasis, teniarinhiaza and others. Unlike the analysis of helminth stools, the scraping material is collected from the skin around the anus using a cotton swab, a wooden spatula, glass eye sticks or adhesive tape. The procedure for collecting material for the analysis of helminth eggs is performed early in the morning and the patient should not be washed in the evening or in the morning.

Important point: even re-analysis of helminths in this way does not guarantee the reliability of the result in case of enterobiosis. Female squirrels lay eggs at regular intervals, and if you don't catch the "right moment, " then you can be sure that there are no eggs - no worms.

Analysis of the contents of the duodenum (bile)

The collection of bile is done with the help of an empty stomach. As this method is invasive (unlike methods such as helminth stools, urine collection and perianal scraping), it is prescribed only in strict indications when there is a reasonable suspicion of specific helminthiasis. Bile is tested for strongyloid 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 so-called serological methods for the diagnosis of helminthiasis. In this case, a blood test is performed for helminths, specifically for antibodies to them.

The main serological method today is enzyme-linked immunosorbent assay (ELISA), which is characterized by high specificity and the highest sensitivity (90%) among all other methods. This means that it allows you to determine quite accurately 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 suitable for detecting the so-called. Tissue helminthiasis, in which worms parasitize in the organs and tissues of the patient (trichinosis, toxocariasis).

Instrumental methods for diagnosis of helminths

It is not always possible to detect helminths using the above methods of laboratory diagnosis, 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 in the body - such is the spinal cord. Certain types of worms have their own means of protection - antienzymes. Those worms that can reproduce the sexual exchange of 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 for detecting and treating parasitic infections.

If the analysis of feces for helminths, blood and other methods does not give effect, in this case such parasites can be detected using the methods of instrumental diagnostics - X-ray, ultrasound, computed tomography, etc. tissues of the liver and spleen. , enlargement of the lymph nodes in the latter, finally, in some cases - echinococci, large clusters-entanglements of intestinal worms - you can see the parasites themselves.

Treatment of helminthiasis

Traditional medicine through trial and error finds a number of plants with anthelmintic properties: aspen, pumpkin, chamomile, tansy, male fern and others. Later, during the time of scientific pharmaceuticals, scientists isolated from them active substances that actually give an anthelmintic effect:

• cucurbitine (pumpkin seeds);
• artemisinin annual wormwood);
• ascaridol (ragweed);
• santonin (citrine wormwood);
• thymol (thyme);
• peletierin (pomegranate root);
• carvacrol (oregano, thyme, bergamot);
• diospirol (persimmon);
• arecoline (palm arec);
• pyrethrins (Dalmatian chamomile);
• tremulacin (aspen);
• nicotine (tobacco) and its isomer anabasine (tobacco and leafless establishment);
• emetine (emetic root).

Even today, a significant proportion of anthelmintic drugs contain the same active substances that once provided the anthelmintic effect of decoctions and tinctures.

conclusions

• Helminthiasis is one of the most common diseases in the world. Everyone in their environment is 100% likely to have people and animals infected with helminths.
• But if the number of individuals in the body is small and the body as a whole is healthy, then the disease can be asymptomatic for many years without manifesting itself in any way.
• Even a regular medical check-up every 3 years or taking tests 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 stubbornly does not help, you should consider taking tests for helminths.
• According to the results of an analysis for helminths, the diagnosis of helminthiasis is not made, as both false positive and false negative results are possible. You should not try to randomly examine yourself at random - it is better to consult a doctor: based on the combination of symptoms, nutritional data and travel data, he will choose tests that will allow to establishexactly whether a person has helminths or not.
• You cannot prescribe helminth pills on your own. The worm medicine may have contraindications for a particular patient and cause serious harm if used incorrectly.