Trichinosis in humans
Trichinosis is one of the varieties of helminthiasis. The disease is caused by the ingestion of a small parasite belonging to the nematode class. Sexually mature Trichinella lays its larvae in the human intestine, and after that, the larvae enter the muscles with the blood flow, and remain there in a dormant state. At 3-4 weeks from the beginning of infection, the larvae develop and are covered with a capsule. The causative agent of the disease is a round worm up to 0.5 mm long, taking the shape of a spiral.
Content:
- Trichinosis prevalence
- Trichinosis infection methods
- The first signs and symptoms of trichinosis
- Diagnostics of the trichinosis
- Trichinosis treatment
- Treating symptoms of trichinosis
- Prevention of trichinosis
- How to check meat for trichinosis?
- How to cook meat to exclude trichinosis infection?
Trichinosis prevalence
Trichinosis in humans belongs to the category of biohelminthiasis, as it is caused by parasitic worms - Trichinella. The disease is diagnosed in both animals and humans. The main species of animals most often affected by trichinosis are: wolf, fox, bear, badger, wild boar. Domestic pigs are also susceptible to this type of helminthiasis. This usually occurs when pigs are free grazing, when the meat of dead animals and small rodents becomes available for them to eat.
The reasons for the widespread prevalence of trichinosis:
- The good adaptability of the pathogen to high and low temperatures provided him with living in many climatic zones;
- The human body is extremely susceptible to this disease;
- Group outbreaks of helminthiasis are not uncommon among members of one collective or one family who ate meat with Trichinella;
- Repeated infections occur due to unstable immunity formed after the primary invasion.
Trichinella mutates, new forms of nematodes that do not form a capsule appear, as well as species that parasitize birds.
Trichinosis infection methods
Trichinella enters the human body by oral route, when eating contaminated meat. Parasites in meat die during heat treatment, so the main risk is undercooked, jerky and raw meat. Infected pork, seal meat, bear meat, wild boar meat are especially dangerous.
The development of trichinosis in the human body after infection:
| Time since infection | Process |
| 1-1.5 hours | The larva, freed from the capsule, is introduced into the mucous membrane of the stomach or duodenum and the connective tissue located under it. |
| 1 day | The larva turns into a mature worm. |
| 3-4 days | A mature female worm lays the larvae (one female is capable of producing from 100 to 2000 new worms). The larvae enter the blood vessels and are transported with the blood stream to the muscles. |
| 42-56 days | The time during which an adult female worm is able to lay larvae. |
| 17-18 days from the moment of deposition of larvae by the female | The larvae mature in the muscles and become infectious to the new host. |
| 3-4 weeks from the moment of deposition of larvae by the female | The larva is covered with a capsule. A year later, the calcification of the capsules occurs. |
| 10-40 years old | This is the period during which the larva in the form of a capsule is able to persist in the musculature of the host. |
The first signs and symptoms of trichinosis
Trichinosis in humans does not cause visible physical harm to the body. There are no changes in muscle tissue. The proteins that make up the body of the parasite are harmful to health. They are very powerful allergens, foreign substances. The strongest allergic reaction caused by them leads to damage to blood vessels and joints.
The incubation period of trichinosis. Lasts from 5 to 30 days, more often 10-25 days. There are no symptoms of the disease. There is a pattern - the more severe the form of helminthiasis, the longer the latent (latent) period.
The peak period. A long period of development of symptoms indicates the development of a severe form of trichinosis.
Mild to moderate form - symptoms:
- Hyperthermia. The temperature rises slightly, more than 37 ° C, the daily amplitude fluctuates within 1 ° C.
- Swelling of the body and limbs. Its cause is an allergic reaction to the introduction of a foreign protein. A characteristic symptom is a "frog face" in a patient.
-
Muscle pain in the upper and lower limbs, muscles of the back, neck, eyes, pharynx, peritoneum. Intense pain begins in the calf muscles, affects the cervical and chewing muscles. The pain increases with palpation and movement. They can begin to disturb the patient from 1-3 days of the introduction of the parasite into the body. Early onset of muscle pain is a sign of severe trichinosis.
Rash on the skin. Has different forms:
- In the form of allergic urticaria - pink blisters of various sizes that turn pale when pressed;
- Itchy blisters raised above the surface of the skin (uterine rash);
- Groups of plaques merging with each other (papular rash).
Complications in severe forms of trichinosis:
- Meningoencephalitis is an inflammation of the lining of the brain.
- Inflammation of the lungs (eosinophilic pneumonia). The disease is caused by an increased concentration of eosinophils in the lung tissue - products of an allergic reaction. Perhaps the development of pleurisy, the appearance of symptoms of bronchial asthma.
- Myocarditis - inflammation of the myocardium due to allergies and an overreacted immune response. More often than other complications, it becomes the cause of the death of patients.
- Nephritis is an inflammation of the kidney tissue.
- Hepatitis is an inflammation of the liver.
- Intense pain in the muscles leads to partial or complete impairment of mobility.
Mortality in severe disease is 10-30% of the total number of patients. The most frequent period of onset of deaths is 4-8 weeks from the onset of infection. In milder forms, patients recover after 5-6 weeks.
Trichinosis symptoms depending on the stage of the disease
The manifestation of trichinosis at an early stage of the lesion depends on the concentration of parasites in the body. Further development of the disease depends on the spread of the larvae in the muscles and the state of the patient's immune system. The most severe complications of helminthiasis are associated with an inadequate response of the body to the introduction of a foreign protein into the body, and not to the activity of Trichinella and their larvae.
| Stage | Time from the moment of infection | Symptoms |
|
7 days |
Trichinella larvae, ingested orally, are located in the small intestine. They become fixed in the mucous membrane, causing inflammation of the intestinal wall. Within 55 days, larvae develop into sexually mature individuals in the small intestine, their fertilization and the appearance of a new generation of larvae. One female Trichinella produces up to one and a half thousand individuals. Symptoms of the early stage of trichinosis:
|
|
2-4 weeks |
The larvae begin their migration in the tissues of the body, penetrating into the muscles. They make their way from the intestine through the blood and lymphatic vessels. After penetration into the blood, Trichinella larvae are fixed in the fibers of the muscles. They develop, grow, releasing allergens into the blood. Intoxication begins in the body, allergic reactions develop.
|
|
6 weeks to 6 months after infection |
During this period, tissue regeneration occurs. The larvae reach a size of 0.8 mm, take a spiral shape. A foreign inclusion (larva) is fenced off by a capsule from muscle tissue and stops developing. Trichinella toxins do not enter the body, the symptoms of the disease become less intense and gradually stop. The capsule is calcified, these salts can destroy the larva. Sometimes the Trichinella larva remains viable for up to 25 years, without affecting human well-being. Regeneration phase symptoms:
The symptoms of the disease can be blurred, disguised as other diseases. There are three signs of trichinosis, always recorded by the doctor after eating contaminated meat:
|
Symptoms of trichinosis in humans may be similar to the manifestations of myositis, allergies, and infectious diseases. This picture leads to the fact that the patient is unaware of the appearance of helminthiasis.
Symptoms of trichinosis in children
To infect a child, it is enough to eat a small piece of meat with trichinella weighing 10-15 g, which has not undergone a full heat treatment. The latent period lasts from 5 to 45 days. The shorter this period, the more severe the form of the disease in the child.
-
Early symptoms. Lasts 7-14 days, after recovery, slight symptoms are noted for 7-10 days.
- Hyperthermia up to 38.5 ° C:
- Slight puffiness of the face;
- Mild muscle pain;
- Swelling of the eyelids;
- Increase in the concentration of eosinophils by 10-12%.
-
Symptoms at the moderate stage. The acute period lasts up to 3 weeks, rehabilitation - 2-3 weeks after recovery.
- Hyperthermia up to 40 ° C, antipyretic drugs reduce it by no more than 1 ° C;
- Pain in muscles, joints, abdomen, and throat;
- Skin rash;
- Puffiness of the face;
- Results of a general blood test: ESR is increased (above 17 mm / h), leukocytes are increased (up to 8.8 · 10 9 / l), the concentration of eosinophils is increased to 25-40%.
-
Symptoms at a severe stage. It is treated in the infectious diseases department of the hospital; without therapy, the child may die.
Symptoms at a severe stage - Hyperthermia up to 41 ° C;
- Enlargement of the liver and spleen;
- CNS disorders: delirium, agitation, epileptic seizures;
- Attacks of severe abdominal pain;
- Diarrhea, nausea, vomiting;
- Severe muscle pain, complicated by cramps;
- Subcutaneous hemorrhage and rash;
- Indicators of a general blood test: Leukocytes up to 30-40x10 9 / l; ESR up to 50-60 mm / h; eosinophil concentration up to 80 - 90%;
- Cylinders and proteins in urine.
Treatment of trichinosis in children is carried out with anthelmintic drugs (Tiabendazole, Vermox) in accordance with the child's body weight and age.
Drugs for the symptomatic treatment of trichinosis:
- Ibuprofen, Paracetamol - to reduce fever, relieve pain;
- Tsetrin, Loratadin - antihistamines to reduce intoxication and manifestations of allergies;
- Papaverine, No-shpa - antispasmodics to relieve pain;
- Vitamins of groups C and B to enhance immunity.
Rehabilitation after the disease is carried out with the help of massage sessions, baths with sea salt and medicinal herbs, and a complex of medical gymnastics.
Diagnostics of the trichinosis
General blood analysis. With trichinosis in a person, the content of eosinophils, a type of leukocyte, increases significantly in the blood. The concentration of white blood cells most often increases with powerful allergic reactions, including allergies that accompany trichinosis.
Changes in blood composition diagnosed with trichinosis:
- The number of eosinophils reaches from 50 to 80% of the total number of leukocytes;
- An increase in the concentration of leukocytes is a sign of activation of immunity and the presence of an inflammatory process in the body.
These symptoms appear immediately after infection, and persist 2-3 months after recovery.
Serological diagnostics. An analysis of the reaction of the blood to the attachment of antigens obtained from nematode larvae is carried out. Antibodies to them are formed as a reaction to the introduction of helminths.
Types of serological diagnostics:
| Abbreviation | Decoding | The essence |
| RSK | Complement binding reaction | If there are antibodies in the patient's blood, then they combine with the antigen and attach to themselves the complement molecule - a special substance that participates in immune reactions. In this case, the reaction will be considered positive. |
| RNGA | Indirect hemagglutination reaction | It is based on the ability of erythrocytes to stick together when an antibody and antigen are on their surface. |
| ELISA | Linked immunosorbent assay | A reaction is carried out between antibodies and antigens. Special enzymes serve as a label that allows you to evaluate the result. |
| REEF | Immunofluorescence reaction | There is a special label in the material that causes a glow after the antibody reacts with the antigen. |
| REMA | Reaction of enzyme-labeled antibodies. | The result can be assessed using a special label, which is an enzyme. |
Intravenous allergic test. It is carried out to provoke an allergic reaction in response to the administration of the trichinosis antigen. A portion of the antigen solution is injected under the skin. The presence of the disease is diagnosed by the appearance of hyperemia and redness at the injection site. This method can diagnose trichinosis starting from 2 weeks of nematode infestation. A positive result of an allergy test lasts for 5-10 years.
Muscle biopsy. It is carried out in the absence of a positive result from other research methods. Biomaterial obtained with a needle from the patient's muscle is examined under a microscope.
Study of the meat of sick animals. At multiple magnification, the meat of the animal is examined - the alleged source of infection. Using a microscope, capsules with larvae are found in the tissues of a sick animal.
Trichinosis treatment
Anthelmintic drugs (treatment aimed at combating the causative agent of the disease):
- during the first three days; 100 mg 3 times a day;
- the next 10 days; 500 mg 3 times a day.
Children under 7 years of age: 25 mg of the drug 3 times a day. Children aged 7; 9 years: 3 times a day, 50 mg. Over 10 years old:
- during the first three days; 100 mg 2 - 3 times a day;
- then for 10 days, 500 mg 3 times a day.
Take after meals. (; Complete reference book of an infectious disease specialist; under the editorship of DMN, prof., Corresponding members of RAE and REA Eliseeva Yu. Yu.,; Eksmo;, 2007)
| A drug | Indications and effects | Mode of application |
| Disrupts the absorption of glucose by worms and the synthesis of ATP in their body - the main carrier of energy. As a result of metabolic disorders, worms die. Mebendazole is contraindicated in pregnant and lactating mothers. |
0.3 - 0.6 g (1 - 2 tablets 0.1 g three times a day) for 10 - 14 days. (Handbook "Vidal", 2010) |
|
| It works in much the same way as Mebendazole. Most active against larval forms of worms. Available in 0.2 gram tablets. Contraindicated in pregnancy, diseases of the retina. |
Take at the rate of 10 mg per kilogram of the patient's body weight for 10 to 14 days. (Handbook "Vidal", 2010) |
|
| Active substance; mebendazole. The efficiency is 90% |
Adults take during the first three days - 100 mg 3 times a day. The next 10 days - 500 mg 3 times a day Children under 7 years of age: 25 mg of the drug 3 times a day. Children aged 7 to 9 years: 3 times a day, 50 mg. Children over 10 years old take during the first three days - 100 mg 2 - 3 times a day, then for 10 days 500 mg 3 times a day Take after meals. ("Complete handbook of infectious diseases" under the editorship of DMN, prof., Corresponding members of RAE and REA Eliseeva Yu. Yu., "Eksmo", 2007) |
|
| The efficiency is 90%. |
The dose for children and adults is 25 mg per kg of body weight (dose (mg) = body weight (kg) * 25). Divide into 2 doses every 12 hours. The course of admission is continued for 3 - 5 days, after which, according to indications, it is repeated after 7 days (as prescribed by a doctor). Take one hour after meals. ("Complete handbook of infectious diseases" under the editorship of DMN, prof., Corresponding members of RAE and REA Eliseeva Yu. Yu., "Eksmo", 2007) |
Treating symptoms of trichinosis
|
They help to cope with inflammation caused by allergic reactions in the patient's body. | As prescribed by a doctor. |
|
Shown when the body temperature rises above 38; C. | As prescribed by a doctor. |
|
Hormonal agents that suppress the immune system and allergic reactions. | Hormonal drugs are used only strictly as directed by a doctor. |
The high probability of death, the frequent transition of the disease to a severe form, a large number of complications are good reasons for treating trichinosis exclusively in a hospital setting. Despite this, 10 to 30% of cases are fatal.
Patients with severe muscle damage require careful care, as patients are completely immobilized and bedridden. To restore mobility, patients are rehabilitated using massage and physiotherapy methods.
Symptomatic treatment of trichinosis in humans is complemented by vitamin therapy, drugs to stimulate blood circulation, to protect the liver and brain (in case of damage to these organs).
Prevention of trichinosis
Trichinosis prevention measures:
- Cooking meat (especially pork) should be carried out at a high temperature - at least 74 ° C inside a piece of meat for at least 15 seconds. Under such conditions, Trichinella larvae will certainly die if they have not yet become covered with a calcified capsule. Otherwise, the larvae will not suffer even with this heating. The larvae manage to become covered with a capsule during a long course of the disease in an animal that carries Trichinella.
- An effective way to kill Trichinella is to freeze it for 20 days at -15 ° C, or hold it for three days at -20 ° C.
- When breeding pigs, they should not be allowed to graze freely to prevent animals from eating infected carrion. It is necessary to regularly destroy rats in the place where animals stay and in the backyard of the farm.
- Especially dangerous is the consumption of meat from wild animals infected with trichinosis. The types of nematodes that parasitize the muscles of bears, badgers and seals are markedly different from the Trichinella species of pigs. They do not die even after prolonged freezing. Long-term thermal cooking of such meat is required. Meat of wild birds can also be dangerous in this regard.
Mass events for the prevention of outbreaks of trichinosis
Rospotrebnadzor conducts systematic monitoring of the conditions of keeping animals intended for breeding for meat. Sale of meat is not carried out without testing it for trichinosis. Such control is carried out on the market and in specialized stores. The safety of meat sold in spontaneous retail outlets is not guaranteed.
How to check meat for trichinosis?
Trichinella larvae are found in many animal species. Meat for human consumption must undergo epidemic control. The most dangerous types of meat are pork, bear meat, wild boar meat.
The appearance of contaminated meat practically does not differ from that of a healthy carcass. The concentration of Trichinella in the affected tissue reaches 200 pieces per 1 gram. Inspection of meat is carried out in the laboratory using a microscope. After analysis, a special stamp is put on the carcass.
Where can a trichinosis test be done?
In the sanitary epidemiological station or in the veterinary laboratory of the food market, samples are taken from the carcass of the animal. Samples of no more than 5 g are taken from areas of increased blood supply: masticatory muscles, tongue, intercostal muscles, diaphragm.
Even one discovered Trichinella is a reason for the destruction of all carcasses, from that time considered unfit for food.
Veterinary laboratory control is absent in spontaneous markets, during mass slaughter of livestock, when hunting trophies are consumed. Unfortunately, Trichinella spp. Can be found in up to 30% of the meats considered fit for food. Prevention of infection - thorough cooking of meat. This is especially true when eating game in regions endemic for trichinosis.
How to cook meat to exclude trichinosis infection?
The Trichinella larva in the thickness of the muscle tissue can be reliably protected by the capsule from damage. This does not make it less dangerous, it also increases the protection of the parasite from extreme temperatures. Hunters who hunted game, and villagers who raise and butcher pork in their backyard do not always conduct research on trichinosis. Proper cooking of meat can prevent the disease.
The main thing is to reach a temperature of 80 ° C within 15 minutes throughout the entire thickness of the piece.
The best way to cook meat:
- Boiling meat for 2.5 hours, cut into pieces no more than 8 cm thick;
- Frying and stewing meat for 1.5 hours (pieces should not be thicker than 2.5 cm);
- Lard is allowed to be consumed only in melted form.
Dangerous meat products:
- Homemade and uncooked smoked sausages;
- Meat frozen at insufficiently low temperature;
- Minced meat dishes;
- Raw bacon and meat;
- Steaks with blood;
- Baked ham;
- Smoked and dried meat.
Author of the article: Danilova Tatyana Vyacheslavovna | Infectionist
Education: in 2008 received a diploma in General Medicine (General Medicine) at the Pirogov Russian Research Medical University. Immediately passed an internship and received a diploma of a therapist
