Helminths

Helminthiases, or diseases caused by helminths, are 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 is not surprising, because you can infect 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 at 270 cases per 100 thousand population, but the actual incidence is, according to experts, several times higher. This is due to the fact that a person often does not even notice that an uninvited guest has settled in her body. If helminths do not manifest in any way, the disease can remain undiagnosed for decades.

All 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 to the detriment of others. In addition, we are talking about endoparasites, ie life within 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 reproduce efficiently.

Accordingly, helminths are parasitic worms. The very term "helminths" was once introduced by Hippocrates. In the people, these unpleasant creatures are also called worms - from the ancient Greek word, which only means 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".

Various helminths in humans

In total, scientists know about 287 species of helminths that can parasitize humans. Only 65 species have been identified in our country, 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 mostly the small intestine, where you can find ascaris, pinworms, three types of tapeworms, broad tapeworms, ankylogia, etc. Vlasoglav occupies one large intestine.

In the liver, more precisely in its bile ducts, as well as in the gallbladder, flukes, opisthorchiasis, etc. can be found. Pulmonary flukes are deposited in the lungs. Trichinella acts on muscles. Adult swine 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 on the skin.

Types of helminths that live in humans

Helminths, whose species are most interesting to physicians, 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 shape of a circle, and in flatworms 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 gut. This group includes roundworms, pinworms, Trichinella, whips, etc. , Which differ greatly 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. They are not difficult to distinguish in adults: females are usually twice as large, and in addition, in males the "tail" is curled towards the "belly".
• Trematodes. The body of the trematode resembles a leaf or lancet in shape and cannot be compared in size with other helminths: these are small worms, a few millimeters long to 3, 5-5, 5 cm. Unlike roundworms, trematodes have a pair of tits in their mouth and abdomen. Their digestive system is in its infancy. A significant part of the species from this group are hermaphrodites, ie they combine the characteristics of both sexes. The exceptions are schistosomes that have both males and females.
• Cestode. Cestodes are worms, which are a long strip chopped into short segments, at one end of which is a head with hooks and tits. These worms live exclusively in the small intestine - their whole body does not fit into any other organ. And that is not surprising, because the length of the ribbons can reach 10-11 meters. They do not need the digestive system at all, because 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 middle host (these can be animals, fish, mollusks and, of course, humans), and the carrier of the adult forms is called the final host.

Depending on whether a particular type of worm has a stage of development in the body of the middle host, they also speak of bio- and geohelminthiasis.

• Geohelminths do not have such a phase. The eggs of the worm fall into the ground, where they wait until, by the will of fate, they enter the body of the future owner. Geohelminths include whips, roundworms, bumps, etc.
• Biohelminths have such a phase and can be several hosts. Examples include Trichinella, tapeworms, schistosomes, all flatworms, and so on.

Some scientists now use the transmission mechanism to distinguish between 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 helminth life, anthroponoses and zoonoses are isolated.

• The first category includes helminthiasis, in which a person is an obligatory phase 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 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 a helminth infection occur?

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

However, food is not the only route of helminth infection. Eggs can enter the human body by inhaling dust. And diagnostic worms and schistosomes enter the body through the skin - and are called infectious worms, and the route of infection is percutaneous. And since schistosomes can be picked up while swimming in a pond, this route of infection is also called aqueous.

In the tropics lives a filamentous plant, it is also a vuhereria that spreads with the help of mosquito bites. And this is the vector way of transmitting the infection.

Helminth infection can also occur through contact with animals - infected cats and dogs. Usually people are rich in roundworms (toxocara, etc. ) and tapeworms from animals. Pets, in the process of licking, carry helminth eggs through their fur. A person who has pardoned such an animal and does not wash his hands immediately afterwards risks injecting the infection into his mouth. Another possibility of worm infection is cleaning the garbage without gloves.

How do helminths affect the body?

Mechanical impact

This category includes any helminth actions that disrupt the integrity of the host tissue. For example, adult helminths with hooks and teats are repaired with their help, while damaging the lining of the digestive tract. As a result, tissue erosion develops in the area of worm localization, ulcers and disorders of the nutritional processes of the mucosa are created, which can even lead to its death (necrosis).

Moving through the body, so-called migratory larvae can also cause bleeding and inflammation in damaged areas - this facilitates their deep penetration into 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 a person’s death.

Host malnutrition

First, the helminths themselves "rob" the host, consuming the food they ate. Secondly, some human helminths feed on blood themselves - they do blows and whips or take substances necessary for hematopoiesis. Therefore, anemia may develop in the background of a parasitic infection.

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

Poisoning of the human body by helminth toxins

Metabolic products of beetles and tapeworms destroy erythrocytes, and ascaris secretions cause capillaries to expand and, as a result, to bleed.

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

Allergy to helminth proteins

Helminths are foreign organisms to us, so our body perceives many of the proteins they secrete (in the process of vital activity or after death) as a potential danger and can consider them antigens. During sensitization to these antigens, antibodies are formed - immunoglobulins IgE and IgG-4. These antibodies, 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, which are found, as mentioned above, in the small intestine, can cause a decrease in stomach acidity. And that 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, thus ensuring a pleasant existence for a long time. This is an evolutionary adaptation they have acquired while adapting to a narrowly defined host circle. But suppressing the human immune system leads to increased vulnerability to other infections and diseases.

Risks of cancer

Some chronic helminthiasis significantly increases the likelihood of cancer. During their vital activity, parasites destroy tissues and organs and thus cause the development of malignant tumors in this place. Cancer often develops in the background of opisthorchiasis, schistosomiasis, clonorchiasis, etc.

Stages of helminthiasis

What are the signs of helminthiasis? After the worm enters the body, the symptoms of the infection will depend on the stage of the disease.

During helminthiasis there are 4 main stages:

• Acute (early) phase of helminthiasis. At this stage, the causative agent of the infection enters the human body, leading to sensitization of the body to helminth proteins. The first symptoms of helminths appear 2-4 weeks after infection. Allergic reactions usually develop during this period - itchy skin, conjunctivitis rash, cough, swollen lymph nodes, inflammatory processes in the joints, analyzes show an increased concentration of eosinophils, etc.
• Latent (latent) phase. In this phase, the helminth develops into an adult state and is finally determined by the place of permanent residence, after which the helminthiasis passes into the chronic phase.
• 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 cause 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, making them impossible to diagnose. Specifically, there are several helminths, whose symptoms are very characteristic, but even they need to be checked using numerous tests.
• Exodus phase. This term means either complete recovery of the patient, or his disability in the background of complications of helminthiasis. These include malignant tumors in opisthorchiasis and schistosomiasis, liver cirrhosis, etc.

Helminths: symptoms of infection

How helminthic invasion (helminth invasion into his body) will affect the human body is determined by many factors: the mode of penetration, the extent of infection, the duration of the disease and the life span of the helminth, the characteristics of its food and developmental 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;
• increased levels of eosinophils in blood test results;
• slowed 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 in which it is 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, two or after a few years. That is, no signs of helminth infection will be visible during this time.

Manifestations of helminth infection in children

Helminths are more common in children than in adults. This is explained by the lack of hygienic 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 the playground, beds in grandma's dacha, someone else's toy played by an infected child, etc.

What are the most common complaints 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, in the background of helminth infection, children developed immune disorders (19%) and bruxism, ie tooth grinding (16%). It is paradoxical, but the general population 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 of detecting parasitic worms alone can serve as a basis for making a definitive diagnosis. According to doctors, in some cases a positive result can be achieved only 8-10. Put! There can be many reasons for this: females lay eggs at different intervals that do not coincide with the moments of sampling, the biomaterial samples were shown to be empty because they were taken in the wrong place, the disease was at such a stage that it was determined by methodsselected almost impossible, etc.

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

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

How is feces tested for helminth eggs?

For analysis for helminths, 50 g of the patient's feces is enough (that is about 1 tablespoon). Today, you can buy a special clean container for tests in the pharmacy, in which you will have to collect feces for helminth eggs. It is better to give the sample to the laboratory on the same day (for strongyloidiasis and hookworm - no later than 4 hours after collection). If necessary, you can store the helminth stool sample for a maximum of one 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 the samples to be stored for up to several months.

Perianal scraping - analysis of helminth eggs

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

Important point: even repeated analysis of helminths in this way does not guarantee the reliability of the results in case of enterobia. Pinworm females lay eggs at regular intervals, and if you don't catch the "right moment", you can be sure that there are no eggs - no worms.

Analysis of duodenal contents (bile)

Bile is collected using an empty stomach probe. Because 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 particular helminthiasis. Bile is examined for characters of strongyloides and lichen ankylosis, and individual parts of the bile are also analyzed for the presence of helminth eggs living in the pancreas and hepatic 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, more precisely, for antibodies to them.

The main serological method today is the enzyme-linked immunosorbent assay (ELISA), which is characterized by high specificity and the highest sensitivity (90%) among all other methods. That is, it allows you to fairly accurately determine the types of helminths that 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 important for the detection of so-called tissue helminthiasis, in which worms parasitize in the patient's organs and tissues (trichinosis, toxocariasis).

Instrumental methods of helminth diagnosis

It is far from always possible to detect helminths using the above methods of laboratory diagnostics, including 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 somewhat 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 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 on helminths, blood and other methods did not give effect, in this case such parasites can be detected by 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 - echinococcus, large clusters-entanglements of intestinal worms - you can see the parasites themselves.

Treatment of helminthiasis

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

• cucurbitin (pumpkin seeds);
• annual wormwood artemisinin);
• ascaridol (ragweed);
• santonin (citrine wormwood);
• thymol (thyme);
• pelletierin (pomegranate root);
• carvacrol (oregano, thyme, bergamot);
• diospirol (kaki);
• arecolin (areca palm);
• pyrethrins (Dalmatian chamomile);
• tremulacin (aspen);
• nicotine (tobacco) and its isomer anabasine (tobacco and leafless pen);
• emetine (emetic root).

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

conclusions

• Helminthiasis is one of the most common diseases in the world. Every person in their environment with 100% probability has people and animals infected with helminths.
• But if the number of individuals in the body is small and the body is generally healthy, then the disease can be asymptomatic for many years without manifesting 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 persistently does not help, you should consider taking tests for helminths.
• According to the results of one analysis for helminths, the diagnosis of helminthiasis is not made, because both false positive and false negative results are possible. You should not try to undergo a random examination on your own - it is better to consult a doctor: based on the totality of symptoms, nutritional data and travel data, he will select tests that will allow to determine exactly whether a person has helminths or not.
• You cannot prescribe helminth tablets on your own. Worm medicine can have contraindications for a certain patient and cause serious damage if used incorrectly.