Trichinosis: symptoms in humans, treatment and prevention

Trichinosis is an extremely dangerous parasitic disease, the acute course of which can have serious consequences for the patient.

Trichinella carriers are predominantly wild animals such as wild boars, bears, badgers, etc. High incidence rates are observed in countries such as the USA, Russia, Belarus, Ukraine, Poland, Germany, and the Baltic states.

In Russia, residents of the Krasnodar, Krasnoyarsk and Khabarovsk Territories, as well as the Magadan Region, most often suffer from trichinosis. It should be noted that cases of infection from domestic animals - pigs, dogs, cats, mice, rats, etc., have already been recorded.

Etiology

The causative agent of trichinosis is a trichinella helical parasite, which parasitizes mainly in the small intestine. The body length of a sexually mature female ranges from 1.5 to 1.8 mm. After fertilization, it reaches 4.4 mm. The body length of the male varies from 1.2 to 2 mm.

Males die immediately after fertilization, and females produce larvae after 2 days. The latter, penetrating the mucous membrane of the intestine, enter the blood and lymph, and are spread throughout the body. As a result, they settle in striated musculature. The process of isolating larvae by females can last from 4 to 6 weeks, after which they die. Young larvae penetrate muscle canals through sarcolemma.

Gradually, they destroy muscle fibers. Infiltrates gradually form around the larvae, and 3–4 weeks after invasion a fibrous capsule is formed. It is penetrated by a network of blood vessels, its walls gradually thicken, and are lined with calcium salts. Trichinella larvae can save their livelihoods for many years. They die only when the meat product is heated to 62.2 ° C.

A person can become infected with trichinosis when eating raw or poorly processed pork or fat with muscle layer.

Trichinosis in meat

Prevalence

Trichinosis is most often detected in wild animals - wild boars, badgers, foxes, wolves. However, in recent years, it is often diagnosed in domestic pigs. This can happen due to the recent consumption of the meat of dead rats or other infected animals.

In humans, trichinosis can develop due to:

  • hypersensitivity of the body to trichinella;
  • temporary immunity: even after an illness the person, although immunity is formed, is so weak that the risk of re-infection with trichinosis still exists;
  • good pathogen survival in any climatic conditions.

It is not uncommon and group morbidity, when trichinosis suffer from several, or even all family members.

In recent years, scientists have identified these types of trichinella, which do not pass the stage of encapsulation, settling in the human body. And another group of parasites, in addition to animals, also infects birds, including domestic ones.

Development cycle

Trichinella penetration into the body occurs when a person eats the meat of an infected animal. After 1 - 1.5 hours after that, the parasite gets rid of the capsule and, with the help of gastric juice and enzymes, enters the small intestine.

Young larvae reach sexual maturity within 1.5 days after invasion, after which females begin to produce new larvae. The duration of the existence of females is from 42 to 56 days, after which they die. Young larvae, penetrating through the wall of the small intestine, enter the lymphatic system, and then - into the bloodstream. Thus, they reach the striated muscles, where they settle. This process takes from 5 to 8 days.

Usually trichinella affect all muscle groups in the body. The only exception is the heart.

After 2 - 2.5 weeks, the larvae mature and become infectious. During the entire period of their habitation in the muscles, they actively produce hyaluronidase, a substance that subsequently helps them penetrate the muscle fibers. After 3 to 4 weeks after that, they go through an encapsulation phase.

The capsule creates reliable protection for the larva, provides its nutrition, and reliably protects. The end of the development of the pathological process occurs in about six months, when the capsule is covered with calcium salts. However, even after this, the frozen larva of Trichinella is still in the human body for another 25-40 years.

Symptoms of trichinosis in humans

Trichinella per se does not cause visible harm to the body of its carrier. Moreover, the muscles affected by them continue to function fully.

The aggravation of the patient's health is associated with proteins that are produced by parasites, since these proteins are the most powerful allergens. In fact, these are alien bodies that are rejected by the body. And it is the immune response aimed at combating antigens that provokes the appearance of another unpleasant symptoms.

The incubation period of the pathology can last from 5 days to 1 month. But most often this period is 10 - 25 days. Clinical manifestations are completely absent. It is noteworthy that the heavier the degree of the disease, the longer the hidden period of its course lasts.

For mild and moderate trichinosis is characterized by the appearance of symptoms in the form of:

  • increase in body temperature to 37 ° C, while the daily amplitude can fluctuate within 1 degree;
  • swelling of the arms, legs, abdomen, face associated with intense allergy to proteins secreted by trichinella;
  • myalgia Muscle pain has different localization, but it usually affects the dorsal, cervical, eye, pharyngeal and peritoneal zones. At first, the patient complains of intense pain in the muscle area, which subsequently spreads to the neck and chewing muscles. Pain becomes worse when you press on the affected area. They may occur as early as 1-3 days after invasion. With the early development of myalgia speak of a severe stage of trichinosis.

For this type of helminthiasis, a characteristic feature is a skin rash. It is divided into several types:

  1. Hives. It is manifested by the formation of small red blisters that become pale when you press them.
  2. Utricar rash. It is a blistering rash that protrudes above the surface of the skin, and is accompanied by severe itching.
  3. Papules Such rashes look like plaques of different sizes merging with each other.

In severe forms of trichinosis, serious complications may develop:

  1. Meningoencephalitis - inflammation of the meninges.
  2. Eosinophilic pneumonia. Eosinophils are the main indicator of an allergic reaction. With their presence in the tissues of the lung develops inflammation, which can develop into pleurisy, or even allergic bronchial asthma.
  3. Myocarditis is inflammation of the cardiac myocardium, which also occurs on the background of an allergic reaction. It is this pathology that most often causes the death of a patient with trichinosis.
  4. Nephritis - inflammation of the renal tissues.
  5. Hepatitis - an inflammatory lesion of the liver.
  6. Disorders of motor functions arising from muscle pain.

In severe forms of pathology, mortality ranges from 10 to 30%. In mild and moderate forms of the disease, the prognosis is favorable: recovery occurs after 5 - 6 weeks from the moment of initiation of therapy.

Signs of trichinosis at different stages

Clinical manifestations of the disease are directly dependent on the total number of larvae and trichinae individuals in the body of an infected person. The development and symptoms of pathology can be viewed weekly.

1st week after infection

The larva freed from the capsule, penetrating into the small intestine, becomes a mature individual. At the same time, one of its ends literally bites into the mucous wall of the intestine, while the other remains in its lumen.

The period of vital activity of adult trichinella in TC is 55 days, during which each female can produce 1500 larvae. At this time, an infected person may notice the appearance of:

  • diarrhea or constipation;
  • abdominal pains, the focus of which is located in the umbilical zone;
  • nausea;
  • vomiting;
  • decrease or complete loss of appetite.

If you ignore such symptoms, the disease progresses, and other clinical manifestations of trichinosis begin to appear in the patient.

2 - 4th week after infection

Symptomatology triggered the migration of larvae in the body of an infected person, and their settling in the muscles. Young larvae penetrate into the lymph, and then into the blood, with which they enter the striated musculature, where they settle. As they grow, they begin to release toxins, which later provoke:

  1. The formation of preorbital edema. This is one of the most common symptoms of trichinosis. First of all, the oculomotor muscles are affected, with which inflammation and swelling of the tissues around the visual organs are associated. In this case, the entire upper part of the face swells up, "bags" under the eyes are formed. It becomes difficult and painful for the patient to turn his eyes.
  2. Retinal and / or conjunctival haemorrhage. This violation is associated with parasite damage to the walls of blood vessels.
  3. Face puffiness. The main reason is an intense allergic reaction caused by the penetration of the larvae into the tongue and masticatory muscles. On the problem areas, the appearance of red rashes. In severe trichinosis, swelling affects the parenchyma of the internal organs.
  4. Myalgia The symptom occurs when trichinella muscle fibers. First, it manifests itself in the calf area, then spreads towards the hips, abdomen, and shoulders. The more parasites in an infected person's body, the greater the intensity of pain. Sometimes the formation of contractures is possible, the result of which is the loss of the ability to move.
  5. Fever Increase in body temperature to 38 - 40 ° C - the immune response to the presence of parasites and toxins secreted by them. The temperature may not fall for 1 to 2 weeks: it all depends on the severity of the pathology and the timeliness of the start of treatment.
  6. Cephalgia Headache manifests itself when the toxins secreted by trichinella on the brain.
  7. Disorders of the central nervous system associated with poisoning by parasites of nerve cells. The patient has mood swings, depressions, sleep disorders, which, at first glance, are unreasonable.
  8. Rash associated with an allergy to proteins produced by parasites.
  9. Disturbances in respiratory function, accompanied by coughing, apnea, difficulty breathing. Most often, patients suffer from a dry paroxysmal cough, which, however, may be accompanied by the release of thick sputum. It appears on the background of the "struggle" of immune antibodies with antigens, which are the helminths and their metabolic products. As a result, an allergic edema of the pulmonary mucosa occurs, accompanied by the formation of a viscous secretion.
  10. Dysphagia is a disorder of swallowing function that develops when the larvae seize the pharyngeal and lingual muscles.

6 weeks - 6 months after infection

The recovery phase. During this period, the larvae grow to 0.8 mm, after which, settling in the muscle fibers, coiled. A capsule is formed in the surrounding muscle that “blocks” the parasite from healthy tissues. On this the cycle of development and vital activity of trichinella in the human body ends.

Sometimes calcium salts, which are deposited around the capsule, penetrate into it and destroy the larva. But sometimes the latter can be in the body up to 25 years, without harming human health.

This phase is followed by:

  • gradual restoration of all body functions (the process takes from 2 to 3 weeks);
  • the disappearance of myalgia after 1 to 2 months after the attenuation of the pathological process;
  • disappearance of eosinophilia after 3 months.

Trichinosis is not always accompanied by previously considered signs, which creates difficulties for making an accurate diagnosis. Therefore, doctors speak of trichinosis, when a patient has 3 main symptoms at once: hyperthermia, eosinophilia and periorbital edema.

Diagnostics

Diagnosis of trichinosis is based on laboratory tests. In order to clarify the diagnosis carried out:

  1. Coprogram. The study of feces helps to detect the presence of trichinella in the patient's body.
  2. General clinical blood test. Eosinophil elevation is common in trichinosis. The content of these substances reaches 80% in comparison with other leukocyte indicators.
  3. Serological examination. This method is based on the study of the reaction of red blood cells to the activity of antigens - proteins produced by parasites.

Serological diagnosis is carried out in several ways:

  1. Reaction of complement fixation (RSK). Complement is an element that is involved in immune responses. When conducting such a study, the antibodies detected in the blood are grouped with antigens, and subsequently bind to the complement.
  2. The reaction of indirect hemagglutination (rnga). This method is based on gluing blood cells to each other, while antigens and antibodies are grouped on the surface of red blood cells.
  3. ELISA. In this case, the interaction of antigens with antibodies is detected. To determine this relationship, special enzymes are used.
  4. Immunofluorescence reaction (RIF). The material studied has a specific label that causes luminescence when antibodies react to antigens.
  5. Enzyme-Labeled Antibody Reaction (REMA). You can evaluate the test result by a special label that acts as a specific enzyme.

In addition, for the diagnosis of trichinosis conduct:

  1. Intravenous allergy test. As an allergen, the helminth antigen is injected, and if the disease does occur, the treated area swells, turns red, can itch or burn.
  2. Biopsy of muscle tissue. The procedure is carried out after obtaining the results of previously performed diagnostic procedures. In this case, a positive result should not be. For the study used biopsy taken from the lesion.
  3. Analysis of the meat of an infected animal. If the specimen is really infected with trichinosis, then under the microscope capsules with helminths will be visible.

Only on the basis of a comprehensive examination a final diagnosis is made, and the necessary therapy is prescribed.

Treatment of trichinosis in humans

Therapy for trichinosis includes a specific and pathogenetic approach. The main task of etiotropic (specific) treatment of trichinosis in humans is the destruction of trichinella and their larvae, as well as stopping the process of their encapsulation and the destruction of already existing capsules. For this purpose, Vermox drugs are used (duration of treatment is 2 weeks), Tiabendazole (the treatment is the same, but they are less frequently used because of frequent complaints of side effects) or Albendazole.

The most effective specific treatment will be at the very beginning of the development of the disease. If the pathology has moved into the encapsulation phase, or the larvae have already settled in the muscle fibers, the effectiveness of therapy will be much lower. Moreover, the disease may subsequently worsen from time to time.

Specific treatment should be accompanied by the mandatory intake of antihistamine drugs:

  • Zotek;
  • Claritina;
  • Zodaka;
  • Zirtek;
  • Cephrine;
  • Erius, etc.

With severe trichinosis, as well as the occurrence of complications resorted to the appointment of hormonal drugs. In particular, Prednisolone is used in medium or high dosage. The treatment is designed for a short time: 40 - 80 mg of the drug per day for 5 - 7 days. After 7 - 10 days, the dose of prednisolone is reduced. Control examination after treatment of trichinosis is carried out six months later.

When conducting a pathogenetic treatment, antipyretics, painkillers, NSAIDs are used.

Prevention

To avoid infection with trichinosis, you must:

  • subject meat, especially pork, thorough heat treatment;
  • Hold fresh meat in the freezer at a temperature of ˗15 degrees for 20 days, or ˗20 - for 3 days;
  • provide proper care for the pigs, ensuring that they do not eat dead rats;
  • the right approach to cooking meat of wild birds and animals.

No less important is the conduct of sanitary-educational work. SES workers, as well as doctors, should regularly talk about ways of contracting trichinosis, explain how dangerous the disease is, and teach how to prevent it.

Watch the video: What is Trichomoniasis? Sexually Transmitted Infection (December 2019).

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