Do wild animals die from trichinella. Check meat for trichinosis. Trichinosis in the household

Trichinosis(trichinellosis) is a natural focal disease of humans and many species of animals (carnivores, omnivores, rodents, insectivores, marine mammals) and some birds, occurring in acute or chronic forms with severe allergic phenomena.

Pathogen

Trichinosis in animals

epidemiological data

Infection of animals occurs when they eat meat infested with Trichinella larvae. The hosts of this nematode can be more than 100 species of mammals and many birds. There are natural foci supported by wild mammals and synanthropic foci, which include pigs, fur-bearing animals, dogs, cats, and mouse-like rodents.

Symptoms and course

The first symptom of trichinosis in animals is diarrhea, which appears 3-5 days after infection. Its intensity depends on how many larvae have entered the body of the animal with food. Diarrhea usually develops during the development of Trichinella larvae in the intestinal tissues, but can continue after a new generation of larvae has set off to populate the animal's muscle tissues. The acute state usually corresponds to the period of colonization of the muscles by larvae and the formation of capsules around them. In a sick animal, the temperature rises, food is refused, weakness develops, severe exhaustion. The characteristic symptoms of trichinosis in animals are trembling and incoordination. The larvae that settle in the muscles secrete substances that destroy muscle tissue, and multiple foci of inflammation develop in the muscles.

Diagnosis

Lifetime diagnosis of trichinosis is made by immunological methods (ELISA, RSK, etc.). These methods are used in medical practice. In animals, the diagnosis is usually established posthumously - by trichinoscopy or by digestion in artificial gastric juice. At meat processing enterprises, AVT and AVT-L devices are used for group examination of muscle samples for the presence of Trichinella larvae.

Treatment

Treatment of animals with trichinosis has not been developed.

Prevention and control measures

All carcasses of pigs, as well as other animals susceptible to trichinosis, whose meat is eaten by humans, are subject to trichinoscopy.

Veterinary personnel of slaughterhouses and laboratories of veterinary and sanitary examination are obliged to immediately notify the relevant veterinary and medical institutions of all cases of detection of trichinosis, indicating the farm and locality where the infested animal (carcass) came from.

In unfavorable trichinosis farms, the following activities are carried out:

1. the territory of pig and fur farms, settlements is systematically cleared of garbage and corpses of small animals, rats, mice, as well as stray dogs and cats are destroyed;
2. do not allow pigs and fur (cage) animals to be fed the carcasses of foxes, wolves, raccoon dogs, small predators and other animals, including birds susceptible to trichinosis, killed during hunting;
3. the meat of marine mammals (walruses, seals, whales, etc.) is fed raw to fur-bearing (cellular) animals only with a negative result of trichinelloscopic examination (compressor trichinoscopy or digestion in artificial gastric juice);
4. waste, slaughter of pigs, meat of marine mammals and kitchen waste are given to pigs only in a well-cooked form (pieces of meat no more than 1 kg are boiled for at least 2 hours);
5. carcasses of fur-bearing (cellular) animals and birds used for feeding dogs, animals and birds are neutralized by boiling or processed into meat and bone meal.

In a zone unfavorable for trichinosis, it is forbidden for hunters to use untreated corpses and carcasses of animals (birds) for bait.

human trichinosis

Epidemiology

Infection of people occurs when eating raw and insufficiently thermally processed meat of a domestic pig, wild animals (boar, bear, nutria, etc.) infected with Trichinella larvae.

Pathogenesis

Clinical picture

The incubation period for erased and mild disease is 4-5 weeks. (when infected with natural northern strains of Trichinella with low-intensity invasion, it can last longer), with T. of moderate severity - 2-3 weeks, with severe - 7-10 days, with malignant - can be reduced to 1-3 days.
The erased form of T. is manifested by subfebrile temperature, mild myalgia, sometimes pastiness of the face or only the eyelids, and eosinophilia up to 10-12%. In a mild form, pastosity of the face, muscle pains are more pronounced, body temperature rises to 38-39 °, eosinophilia reaches 10-20%. Acute phenomena last about 7-10 days, after which subfebrile condition, mild myalgia, pastosity of the face may remain for several weeks.
T. of moderate severity is characterized by a rapid increase in body temperature to 39-40 °. Relapsing fever is accompanied by myalgia, arthralgia, swelling of the face, exudative or polymorphic skin rashes. Catarrhal phenomena of the upper respiratory tract are not uncommon, often X-ray reveals "flying" infiltrates in the lungs. Children complain of sore throat, loose stools in the abdomen, but appetite is usually preserved. Detect lymphadenopathy. Eosinophilia reaches 25-40%, leukocytosis - 10-15x109/l. At the height of the disease, ESR increases. The disease without specific treatment lasts 21/2-3 weeks. Glucocorticoids stop all manifestations within 1-2 days, but after their cancellation, all symptoms resume and the convalescence period is often delayed instead of the usual 1-3 months. up to 5-6.
In severe T. the temperature rises to 40-41°. characterized by myalgia, general edema. Often in the initial period, abdominal pain, nausea, vomiting, diarrhea. Temperature curve of constant or remitting type. Eruptions on the skin of an erythematous-papular, hemorrhagic, sometimes pustular-hemorrhagic character. Lymphadenopathy, an increase in the size of the liver, spleen are revealed. Sharp muscle pains lead to contractures. Characterized by tachycardia, arterial hypotension. Infectious-toxic shock may develop. Myocarditis, pneumonic foci of an allergic nature, and often meningoencephalitis are regularly observed. Approximately 1/3 of patients have nausea, vomiting, loose stools, sometimes with an admixture of blood. A number of patients develop sharp paroxysmal pains in the abdomen, hemorrhagic rashes on the skin of the type of hemorrhagic vasculitis against the background of leukocytosis up to 30–40 × 109/l with eosinophilia up to 80–90%. Hepatitis is rare. Characterized by proteinuria, cylindruria. C.N.S. lesions are manifested by agitation, insomnia, delirium, hallucinations, meningism associated with swelling of the membranes and brain substance. With the development of meningoencephalitis, focal symptoms are detected, with a predominant lesion of the cerebral cortex - acute psychoses, epileptiform seizures. The level of eosinophilia is inversely proportional to the severity of this form of T. Aneosinophilia against the background of neutrophilic leukocytosis is an extremely unfavorable prognostic sign. ESR at the height of the disease reaches 50-60 mm/h.
In the malignant course of T. in the coming days (sometimes hours) after infection, nausea, vomiting, and dysentery-like stools appear against the background of severe intoxication with impaired consciousness. During the 1st week of the disease, signs of damage to the myocardium, lungs, central nervous system are revealed. Muscle pain, swelling of the face occur only on the 2nd week of illness. The cause of death in the 1st-2nd week is shock, collapse, ulcerative-necrotic lesions of the stomach and intestines with bleeding and perforation, thrombosis of cerebral vessels. On the 3rd-4th week, patients die from cardiovascular and pulmonary insufficiency as a result of damage to the heart, lungs, development of vasculitis, meningoencephalitis.

Diagnosis

Prevention

Trichinosis- helminthic disease of animals, as well as humans, in which predominantly striated muscles are affected. It is caused by roundworms - trichinella (Trichinella spiralis), belonging to the family Trichinellidae and to the suborder Trichocephalata. This disease occurs mainly in pigs and rats, sometimes in dogs, bears, foxes, mice and cats. In humans, trichinosis is observed quite often in areas where pigs are affected by trichinosis.

The economic damage from this disease is enormous: pork carcasses affected by trichinosis are either neutralized, which reduces the value of meat, or destroyed; some pigs die at the onset of the disease. But trichinosis is especially dangerous for people; they are seriously ill with this helminthiasis and often die from it. The state in the fight against this disease spends a lot of money on the organization of trichinoscopy.

Trichinella larvae after birth reach 0.08 - 0.12 mm in length and 0.006 mm in width; their head end is equipped with a stylet. In muscles, they elongate to 0.1 - 1.15 mm, spirally fold and encapsulate.

The newly born Trichinella larvae, very small in size, first enter the lymphatic and then the circulatory system. They are carried by the blood stream throughout the body, enter the striated muscles in large quantities and penetrate under the sarcolemma of the muscle fibers. At first they grow, and then spirally fold and become covered with a capsule. In this capsule, the Trichinella larva remains immured until the meat is eaten by any animal or person in whose intestines the sexually mature form develops from the muscular Trichinella. Trichinella larvae cannot develop in the heart muscle, because the fibers of the latter lack the sarcolemma. Trichinella are found in fat, in the pectoralis major skin muscle, in the muscles of the esophagus.

Sometimes single specimens of females and males of Trichinella perforate the intestinal wall, and move into the mesentery, abdominal, and less often into the chest cavity. The female at the end of the allocation of larvae, on the 25th - 45th day of her life, leaves the intestine and dies. The larvae (muscular Trichinella) can live in the body for a very long time, for many years (up to 25), without losing their viability. One female Trichinella gives birth to from 1500 to 10 thousand larvae.

In the muscles of killed pigs, Trichinella also do not lose their viability for a long time. Drying out kills them pretty quickly.

Pigs become infected with trichinosis mainly when they eat rats or dead pigs whose muscles contain encapsulated Trichinella larvae. People get trichinosis after eating untested (or poorly cooked) trichinosis meat.

Health value of trichinosis. A person becomes infected with trichinosis only when eating infested meat of pigs, wild boar, bear. Trichinosis is a focal disease, but in humans it occurs very often in almost all European countries. It is especially widespread in the United States (in various states, the infection rate of the population ranges from 5 to 36%). In the USSR, foci of trichinosis are known in some regions of Ukraine, Belarus, Ryazan and Kirov regions.

Outbreaks of trichinosis in humans are observed in cases where pork is allowed to be eaten, which has not been subjected to trichinosis (ham, poorly fried pork). The protection of people's health from trichinosis is ensured mainly by careful veterinary and sanitary control of pork; unfortunately, this event is often underestimated at slaughterhouses in rural areas, in small farms.

Trichinosis: epizootology. Trichinosis occurs in a large number of species of meat-eating animals and rodents. In the focus of trichinosis, the latter is found in the highest percentage in wolves, dogs, cats, rats and mice (B. F. Bobrov found trichinosis in 96.9% of the examined wolves).

Trichinella larvae are very resistant to external factors. In rotting meat in the air, they do not lose their invasive properties for 120 days. Trichinella quickly die when the meat rots in water. They are killed by a temperature of 70 °, while at - 10 ° they are well preserved. Weak salt solutions and ordinary smoking do not kill them. Rats contribute to the spread of trichinosis. Where deratization is poorly organized, trichinosis remains in the focus for a long time. The source of infection of pigs are the corpses of rats, mice, and sometimes slaughterhouse waste (It must be remembered that wild animals are a reservoir of trichinosis).

Trichinosis: pathological changes. Muscle fibers, into which Trichinella larvae have penetrated, expand spindle-shaped; their transverse striation gradually disappears; nuclei increase; muscle substance turns into a granular mass. Trichinella larvae grow and increase, and a bag gradually forms around them. The latter is formed due to thickening of the sarcolemma and proliferation of connective tissue. After 20 - 30 days, the larva completes its growth in the muscles, begins to coil up in a spiral, and the capsule, as it were, immures it. After a few months (5 - 6) this capsule becomes calcified.

Trichinella are found mostly in the diaphragm, muscles of the tongue, larynx, intercostal, chest; sometimes they are found in parenchymal organs and in the fat of pigs.

Trichinosis: symptoms diseases usually appear on the 3rd - 5th day after infection and only with a very strong invasion. They are expressed in an increase in body temperature, diarrhea, and sometimes vomiting. Pigs quickly lose weight and often die after 12 to 15 days. For the most part, the disease takes on a protracted character; there are muscle pains. Emaciated animals lie motionless for a long time with outstretched limbs. They have shallow breathing, sometimes swelling of the eyelids and limbs. The disease lasts 1 - 11/2 months until the encapsulation process of Trichinella is completed. After that, the animals usually do not have acute disorders.

In humans, the disease is accompanied by fever, disorders of the functions of the gastrointestinal tract, swelling of the face and especially the eyelids, and muscle soreness. Trichinosis, due to the similarity of clinical signs, is often mistaken for typhoid fever. The disease lasts 3 to 6 weeks and may end in death.

Trichinosis: diagnosis. Pork carcasses are subjected to a special study for trichinosis. Its technique is simple and, in the presence of a trichinoscope or microscope, can be performed under any conditions. The appearance of trichinella under a microscope is very characteristic, so it is not difficult to make a correct diagnosis.

For research, from the taken samples of pork meat (two samples from the legs of the diaphragm, weighing no more than 80 g each), cut out with scissors several (20 - 24) pieces the size of a wheat grain, lay them out in rows between two thick glasses of the compressorium and then view them under a trichinelloscope or with low magnification (40 - 50 times) microscope.

Trichinosis: prevention. In order to protect people from infection and prevent the spread of trichinosis, all pigs, wild boars and bears slaughtered for meat are examined for trichinosis. The organization of mandatory inspection of pig meat for trichinosis is one of the most important preventive measures.

When in Germany, after a number of years without diseases, the mandatory inspection of meat was abolished, an epidemic of trichinosis broke out; 400 people fell ill, 40 of them died (E. N. Pavlovsky).

Carcasses of pigs affected by trichinosis should never be eaten. They are either rendered harmless (by boiling in special cauldrons at slaughterhouses), or destroyed in case of intense damage.

According to existing rules, if no more than five Trichinella are found in 24 sections, regardless of their viability and stage of development, the carcass with all organs is neutralized. If more than five Trichinella are found in 24 sections, the carcass and by-products with muscle tissue are sent for technical disposal or destroyed. External fat (lard) in both cases is melted.

The fight against rats and mice should be carried out everywhere and especially vigorously in pig farms, slaughterhouses and various warehouses where meat products are stored. It is equally important to keep pigsties clean. To establish the degree of infection with trichinosis of rats, cats, dogs and other possible carriers and distributors of trichinosis in veterinary diagnostic laboratories, systematic studies of the corpses of the listed animals are carried out.

Of great importance in the fight against trichinosis is veterinary and sanitary educational work among the population, especially in areas where this disease is common.

In cases of detection of trichinosis in humans, an epidemiological survey of the settlement is carried out; sick people are registered, treated and carried out according to the instructions for combating trichinosis, approved by the People's Commissariat of Health of the USSR and the Main Veterinary Directorate of the People's Commissariat of Agriculture of the USSR on July 16, 1939.

An unfavorable trichinosis point is considered as a natural focus; it carries out a set of preventive measures.

Trichinosis is caused by the nematode Trichinella spira-lis from the family. Trichinellidae. Trichinosis - anthropozoogelmintosis. The causative agent of this helminthiasis has been registered in domestic and wild pigs, dogs, cats, bears, wolves, foxes, rats, mice and humans. Mature trichinella are localized in the small "intestine, and their larvae - in the muscles. Therefore, two forms of the disease are distinguished - intestinal and muscular. Trichinosis occurs in the form of separate foci, but in some countries (USA and Canada) this helminthiasis is very widespread.

On the territory of the USSR, trichinosis is more often recorded in Belarus, Vinnitsa and Khmelnitsky regions.

Biology of the pathogen. In Trichinella, the same animal or person is successively the definitive and then the intermediate host (trichinelloid type of development). Trichinella females penetrate into the lumen of the Lieberkün glands or into the intestinal villi, give birth to live larvae, which are brought into the muscles by lympho-hematogenous current. The favorite places for the localization of larvae are the muscles of the legs of the diaphragm, tongue, esophagus, intercostal, etc.

After 17 days, they reach the invasive stage (spiral shape). After 3-4 weeks, a lemon-shaped capsule forms around the larva, which begins to calcify after six months. Completely this process comes to an end in 15-18 months. After the formation of the capsule, the larvae are called muscular trichinella. The viability of muscular Trichinella is preserved in animals for years, and in humans up to 25 years. Infection of animals and humans with trichinosis occurs when eating meat containing invasive trichinella larvae. The meat is digested, and the released muscle trichinella after 30-40 hours turn into intestinal ones. Males fertilize females and quickly die. Females after 6-7 days give birth to 1500 to 10000 Trichinella larvae. Females live in the intestines for up to two months (Fig. 43).

Health value of trichinosis. When eating pork, which was not subjected to veterinary and sanitary examination and trichinoscopy, cases of people with trichinosis were recorded in Vinnitsa, Chernihiv and other regions of the country. It should be borne in mind the very high susceptibility of people to infection with trichinosis. Even 10-15 g of invasive pork can cause infection and human disease with trichinosis. But the human body is a biological dead end for Trichinella.

epidemiological data. Trichinosis is a natural focal helminthiasis. The main links in the epizootic chain of this disease are not pigs and rats, as was mistakenly believed before, but wild animals. In some regions of the country, the examined wolves were infected with trichinosis from 96.9 to 100%. Often recorded high infection of domestic carnivores. For example, 146 cats studied in Odessa turned out to be infested with Trichinella on

71.23%, while the infection rate in rats was 6.45%, and in pigs only 0.35%.

The specificity of Trichinella in relation to the choice of hosts is very weak, and in fact they can develop in any host (under natural or artificial infection).

The main sources of infection with trichinosis: pigs - carcasses and corpses of rats, cats, dogs, wolves, foxes, as well as waste from the processing of the skins of these animals, pig slaughter waste (especially household); dogs and cats - rodents, kitchen and slaughterhouse waste, waste from the processing of animal skins; rodents are new - with cannibalism and through food waste; wild animals - 268

rodents, other animals and their corpses; fur-bearing animals * rave in fur farms - slaughterhouse waste.

Pathogenesis. The degree of the pathogenic effect of Trichinella on the body of an animal and a person depends on the intensity of invasion and the resistance of the host organism.

When introduced into the intestinal mucosa, Trichinella females destroy villi and Lieberkün's glands and often inoculate pathogenic microbes. Migrating nematode larvae injure and cause degeneration of muscle fibers. As a result of the sensitizing effect of metabolic products and the breakdown of muscle, as well as intestinal trichinella and allergic reactions, edema develops in the head, eosinophilia and degeneration of parenchymal organs, fever is noted.

Clinical signs with a strong degree of invasion appear on the 3-5th day after infection. They are characterized by fever, diarrhea, emaciation. The appearance of these symptoms is associated with the introduction of Trichinella females into the intestinal mucosa. A few days later, difficulty chewing and swallowing, swelling of the eyelids, eosinophilia are noted. These signs appear as a result of the pathogenic influence of migrating Trichinella larvae in muscle fibers. They are noticeable until the end of the process of encapsulation of larvae in the muscles, after which the disease proceeds chronically. Most often, trichinosis in pigs is asymptomatic.

People have pronounced clinical signs: fever, swelling of the face, diarrhea and soreness of the affected muscle groups. Trichinosis in Belarus is called "puffy-roll".

Diagnosis. For life-long diagnosis of trichinosis, an allergic method is used. The antigen at a dose of 0.1 is injected intradermally into the skin fold of the ear. With a positive reaction at the injection site of the antigen, after 30-45 minutes, a pink or red spot and swelling with a diameter of up to 1.5 "cm appear. At the same time, the skin fold thickens by 5-8 mm (compared to the norm). In practical conditions, it is rarely used. Basic method of post-mortem diagnosis of porcine trichinosis =

trichinoscopy of muscle pieces from pork carcasses in order to detect trichinella larvae. "To test for trichinosis, two samples should be taken from the legs of the diaphragm of each pig carcass.

In the study of imported meat and the absence of "legs of the diaphragm" in it, samples for trichinoscopy are allowed to be taken from other parts of the diaphragm, as well as from the intercostal and cervical muscles.

Trichinoscopy technique. From two samples of meat weighing up to 60 g, curved scissors along the muscle fibers, closer to their tendon part, are cut into 12 pieces the size of an oat grain. The sections are placed on a compressor and crushed to such an extent that newspaper type can be read through them.

Prepared 24 muscle sections are carefully examined under a trichinelloscope, a low magnification microscope, as well as using a KT-3 projection camera or a screen trichinelloscope.

Trichinella larvae are usually found in encapsulated form on muscle sections. Trichinella capsules have a lemon-like shape (0.68X0.37 mm), inside which there is often one spiral-shaped larva.

Often there are larvae with calcified capsules; for their enlightenment, muscle sections are placed for 5-10 minutes in 50% glycerol, lactic acid or 2-5% hydrochloric acid solution, and then examined in drops of glycerin.

The calcified capsules of Trichinella larvae must be differentiated from sarcocysts (Misher pouches) and Finn. Misher pouches are located in the muscle fibers, but their size and shape are variable; they reach 0.1-5 mm in length and 0.2-0.3 mm in width; the shape of the misher bags can be curved, elongated or oval; they do not have capsules. The visibility of the sacs is improved when the sections are treated with a 5% solution of caustic potash.

Underdeveloped or dead and calcified cysticerci (finnous calculi) are always located outside the muscle fibers; their length is 0.03-15 mm. These stones dissolve in a 10-20% hydrochloric acid solution. According to the current legislation, if even one live or dead larvae of Trichinella is detected by any means, the carcass and offal from

it, having muscle tissue, as well as impersonal meat products are subject to technical processing or destruction. Esophagus (pical meat) and rectum are also destroyed. External fat (bacon) is melted at a temperature not lower than 100 ° - for food purposes. Internal fat and intestines (except for the rectum) are available without restrictions. Muscle tissue is carefully removed from the skins of animals.

Treatment has not been developed. Thiabendazole has some effect.

Prevention. One of the most important preventive measures for trichinosis is a veterinary and sanitary examination of all pig carcasses, as well as the meat of wild boars and bears with their obligatory trichinoscopy. The prohibition of backyard slaughter will play an important role in the prevention of disease in humans and animals.

You can not feed pigs and fur-bearing animals slaughterhouse waste from pigs. Carcasses of fur-bearing animals and carnivores after skinning are subject to mandatory disposal. The corpses of dogs, cats, mouse-like rodents should be burned or destroyed in biothermal (py-ryatinsky) pits. It is necessary to exterminate rats by all means, especially in places of slaughter of animals and storage of meat products and on pig farms.

It is advisable to improve the diagnosis of trichinosis. It is necessary to carry out systematic veterinary educational work among the population and instill in them hygienic skills.

The socialist form of agriculture and the successes achieved in the prevention of parasitic diseases in humans and domestic animals create every opportunity for further reduction of trichinosis, up to the total devastation of this dangerous anthropozoohelminthiasis in our country.

Laboratory-practical lesson 17

TRICHINELLOSCOPY OF PORK MEAT AND THE STUDY OF TRINELLA LARVIES

Task: 1) to study the structure of Trichinella larvae on permanent preparations;

2) conduct trichinoscopy of meat samples from a pork carcass;

3) draw a trichinella larva.

Equipment and materials. Trichinelloscopes or microscopes, compressors, tweezers, curved eye scissors, scalpels, bacteriological cups; permanent preparations of Trichinella larvae, canned pork infested with Trichinella larvae, fresh meat samples from the legs of the diaphragm from pork carcasses.

The methodology of the lesson. Students are divided into teams of two. Each link is given a piece of fresh and canned (trichinella) meat. After a preliminary brief explanation by the teacher, the students first look through the l-eggs on permanent preparations under the trichinelloscope, and then proceed to the trichinoscopy of the pieces of meat. Make 22 cuts of fresh meat and two cuts of trichinella meat (in order to save it), crush it between compressor glasses and sequentially examine all sections under a trichinelloscope, starting with sections of canned pork containing Trichinella larvae. The teacher draws the students' attention to the need to differentiate Trichinella larvae from misher sacs and cysticerci (Finn) at an early stage of development. At the end of the lesson, students make schematic sketches of a Trichinella larva.

dioctophymatoses

Dioctophymatoses are called such nematodes, the causative agents of which are nematodes from the suborder Dioctophymata. All pathogens of dioctophymatoses are biohelminths.

HYSTRICHOSIS OF DUCKS

The losses caused by histrichosis to duck breeding consist mainly of a large waste of young

ka ducks (case and forced slaughter) and the unsuitability of a sick bird for breeding purposes.

Morphology of the pathogen. Hystrichis tricolor is a large nematode with a spindle-shaped body, covered in front with numerous large spines. Males are 2.5-3 cm long, have a muscular caudal bursa and one spicule. The size of females varies from 2.5 to 10.5 cm in length and 0.3-0.5 cm in width. Eggs of medium size (0.07-0.08 X 0.042-0.048 mm), oval, yellow, immature. The outer shell of the eggs is cellular.

Pathogenesis. The causative agent of histrichosis has a pronounced mechanical effect in the glandular stomach (perforation of the wall) and other organs, accompanied by an acute disorder of its motor and secretory functions. The death of young ducklings from hystrichosis can occur in the first hours after infection.

Rice. 44. Scheme of the development of the causative agent of histrichosis:

/ - head end of the nematode; 2 - tail end of the male; 3 - egg;

4 - invasive larva; 5 - oligochaete worm.

Clinical signs. With a strong degree of hystrihozny invasion, emaciation, diarrhea, sometimes vomiting, lag in growth and development of young animals are noted, ducklings often die.

Small nodules (about the size of a hemp seed) remain in the stomach. The death of ducklings occurs at the beginning of the disease when the organs of the chest or abdominal cavities are damaged, and at a later time from exhaustion.

test questions

1. What is the difference between toxocaroid and ascaroid types of nematode development?

2. How is group deworming of pigs carried out with piperazine and sodium silicofluoride?

3. What is the essence of chemoprevention of ascaridiosis and heterokidosis in chickens?

4. In what forms is fecothiazine used for strongylatoses in ruminants?

5. How are dictyocaulosis and protostrongylidosis of ruminants differentiated during the life of animals and posthumously?

6. What is the advantage of the aerosol method of deworming sheep and cattle in case of dictyocaulosis?

7. How are earthworms examined to detect metastrongylid larvae in their bodies?

8. How are tetramerosis, streptocarosis and echinuriasis differentiated during the life of birds and posthumously?

9. What is the economic damage to the leather industry caused by onchocerciasis in cattle?

10. How is pork trichinoscopy performed?

Trichinosis is an acute or chronic zooanthroponotic disease of many species of mammals and humans, which has a pronounced allergic character and is caused by larvae and mature nematodes (Trichinella spiralis, Trichinella natuva and Trichinella pseudospiralis) parasitizing in the intestines and striated muscles.

The disease is widespread on all continents of the globe and in all countries.

Trichinosis manifests itself in two forms - muscular and intestinal. Adult trichinella are localized in the intestine, and their larvae are in the striated muscles.

Pathogen- Male nematodes are very small, 1.4-1.6 mm long, 0.14 mm wide. At the posterior end of the body and in the gap between the two lobes behind the cloaca, they have two pairs of papillae; the spicule is absent. Trichinella females are twice as large as males and are 3-4mm long. The females give birth to viviparous larvae. The larvae are 0.08-0.12 mm long and 0.006 mm wide.

epizootology. Humans and more than 100 species of domestic and wild animals (boar, brown bear), rodents, insectivores and marine mammals are susceptible to trichinosis. The source of the causative agent of trichinosis are infested animals. The main route of infection with trichinosis is alimentary, when eating meat and meat waste, animal corpses affected by Trichinella larvae.

The main reservoir of the causative agent of trichinosis are wild animals - wolves, foxes, brown bears, wild boars.

Pathogenesis. The pathogenic effect of Trichinella on the body of animals and humans has a pronounced allergic character. As a result of sensitization by metabolites and decay products of dead Trichinella larvae, systemic vasculitis of a nonspecific nature develops in the body, causing pain and organ damage (myocarditis, pneumonia, etc.). In the early stage of the disease, the mechanical effect of Trichinella occurs, causing damage to the intestinal wall, arterial thrombosis, etc.

Clinical signs. After 3-4 days, with intensive infection, pigs experience depression, diarrhea, and fever. In some animals, these symptoms may intensify and the animals die after 12-15 days with symptoms of cachexia. In practice, fatalities are rare in pigs. The resulting intestinal disorders in most pigs gradually disappear and allergic symptoms appear - muscle pain, head and eyelids swell, some animals develop a skin rash, conjunctivitis, and aphonia. During this period, in sick animals, we note the leading clinical signs for trichinosis - muscle pain and eosinophilia. When getting up and eating, animals feel severe pain. Symptoms of trichinosis reach their maximum by 2-3 weeks, then these symptoms begin to gradually fade away. With a weak infection of animals with trichinosis, the disease is asymptomatic and only eosinophilia (up to 10-12%) indicates a latent course of the disease.

pathological changes. With intensive infection of pigs and other animal species in the small intestines, we note mucous degeneration and desquamation of the epithelium of the villi and submucosal tissue. In the liver, hemorrhages and fatty degeneration and disintegration of the epithelium of malpighian glomeruli in the kidneys. In the myocardium, brain, lungs, liver, we find nodular infiltrates consisting of lymphoid cells and eosinophils. In some cases, trichinella larvae can be found in the nodules. For trichinosis, pronounced interstitial myositis and the formation of connective tissue capsules around the larvae are specific.

Diagnosis. Considering that a pronounced clinic of trichinosis in pigs is observed very rarely, the diagnosis has to be made taking into account the epizootic situation and using immunological diagnostics - an intradermal allergic test. If necessary, a diagnostic biopsy of the muscles of the ear of pigs (temporalis muscle) can be resorted to, which makes it possible to identify 30-60% of infected animals. For post-mortem diagnosis and post-mortem veterinary sanitary examination, trichinoscopy of the legs of the diaphragm is used.

Prevention trichinosis is based on strict observance of veterinary and sanitary rules for keeping animals. Animal owners should exclude the possibility of pigs eating infested corpses, as well as carcasses of wild animals, dogs, cats and rats, as well as raw or poorly cooked slaughterhouse and kitchen meat waste. The meat of pigs, wild boars, brown bears (on the territory of the Vladimir region is listed in the Red Book and hunting is prohibited), badgers and marine mammals (walruses and seals) should be subject to mandatory trichinoscopy and, if Trichinella larvae are found in it, should be destroyed or technically disposed of . Deratization must be carried out on the territories of farms, slaughterhouses, waste plants, warehouses for meat products and raw hides.

Each case of detection of trichinosis in animals is reported to Rospotrebnadzor and the leadership of the veterinary service of the region.

Infested meat Once in the stomach, it is digested, Trichinella larvae are released from the capsule and, moving along the gastrointestinal tract, enter the small intestine, where they are introduced into the mucous membrane, located between the intestinal villi. There, the females are fertilized; larvae are formed in the uterus; on the 4th day, each female gives birth to up to 2 thousand larvae, which penetrate into the lymphatic and blood vessels, spread through them to all organs and tissues, with the bulk of the larvae being selectively localized in the skeletal muscles, where the larvae go through several stages of development. By the 14th day of infection, muscle fibers thicken, the transverse striation is lost, they expand fusiformly, the larvae twist, become invasive, a capsule is formed, which takes on a shape from oval to round (by day 60). Once in other organs and tissues, the larvae die.

In the vast majority of cases, the transmission factor for trichinosis is the meat of domestic pigs, wild boars; also, infection is possible through the meat of wild carnivores, the same become infected by eating mice and rats and by feeding them with waste from the slaughter of trichinella animals.

Trichinosis is more often registered in pigs with free grazing, when they have access to carrion.

Human infection occurs when eating meat and meat products obtained from infested animals. You should know that Trichinella larvae are highly resistant, when neither boiling, nor roasting, nor smoking, nor salting fully releases meat products from them.

The disease in humans usually manifests itself 3-4 weeks after eating infested meat, but may appear after a few days. The more intense the infection, the shorter the incubation period.

The disease in humans is characterized by: fever up to 38 degrees and above, weakness, muscle pain, swelling of the eyelids and face (hence the popular name "puffiness"), skin rashes, intestinal upset. The disease can occur in erased or mild forms, but it can also be in severe forms that end in death.

In order not to become infected with trichinosis, the following preventive measures must be observed:

• In no case should pigs be fed slaughterhouse waste from meat processing plants, even after normal boiling, as well as meat and carcasses of animals both from animal farms and hunted.
• Do not allow pigs to wander around the territory of farms, settlements in wastelands, ravines and forest clearings.
• Farms should be regularly derattized, including pigsties, exercise yards and summer camps.
• Buy pork meat only in official markets, where pork is tested for trichinosis in the veterinary sanitary examination laboratory.
• You can not buy pork meat, wild boar meat from friends and in unidentified places of trade.

Hunters of hunted wild boars, brown bears (the brown bear in the territory of the Vladimir region is listed in the Red Book and hunting for it is prohibited) are required to check in the laboratories of the veterinary sanitary examination of the shot wild animals for trichinosis.

In the wild, infection of animals occurs when carnivores eat the meat of infected animals during hunting (predators), while eating carrion (jackals, foxes). Infection of omnivorous boars, rats, mice, and some species of birds is associated with the consumption of infected feces, skin residues, and carrion.

How do trichinella develop?

If earlier it was believed that Trichinella enters the intestines of animals in two forms: in the form of live larvae or in the form of calcareous capsules, with a "filling" in the form of invasive Trichinella larvae, now scientists have discovered and registered a new type of Trichinella - a capsular, the carrier of which can be even such a well-known vegetarian as a beaver.

Live larvae enter the body of a new host when it eats the intestines of a killed infected animal, where these larvae are located, or with the faeces of infected animals, which is rare.

Invasive larvae of Trichinella, enclosed in calcareous capsules, are found in the muscle tissues of animals. When such meat enters the body, lime capsules dissolve under the action of intestinal enzymes, and Trichinella larvae are able to produce offspring 2-7 days after entering the intestines of animals. Male individuals - Trichinella fertilize females, which in 6-7 days give birth to from 1000 to 1200-20000 thousand live larvae. Having fulfilled their biological role, adults die and after a while are excreted with feces.

Live larvae of Trichinella, picked up by the lymph current, penetrate into the muscles. Their "favorite" habitats: muscles of the tongue, esophagus, abdominal, cervical, intercostal. When a beaver was butchered, the larvae were found in the muscles of the tail. After 15-20 days, the larvae take the form of spirals and reach the invasive stage. After 1 - 1.5 months, the spiral of the larva begins to encapsulate, and later a calcareous shell is formed. In this state, in the muscles of animals, Trichinella larvae retain their ability for years, until the death of the animal..

For a long time it was assumed that herbivorous mammals are not susceptible to trichinosis invasion. So, for example, Goreglyad Kh.S., Doctor of Veterinary Sciences, Professor, Academician of the Academy of Sciences of the BSSR, in his monograph “Diseases of Wild Animals” in 1971, argued whether beavers can get sick with trichinosis.

Goreglyad Kh.S. wrote: “Although the river beaver feeds mainly on wood, bark and plant foods and is not a carnivore, the beaver is quite susceptible to trichinosis. But he (the beaver) can be infected with trichinosis by eating the roots of plants, along with the soil, containing encapsulated Trichinella larvae. Or the beaver may be susceptible to infestation through water, in which meat containing Trichinella larvae has been rotting for a long time. However, cattle, sheep, horses, deer, elk, bison have a natural immunity to trichinosis.

Recently, beaver meat has become very popular, one might even say “fashionable”. First of all, this is due to the fact that the beaver is considered an environmentally friendly animal that is not prone to trichinosis. However, in the course of recent studies it has already been proven that a beaver can both get sick and be a carrier of the larvae of this formidable disease.

Special care should be taken with this exotic meat, including elk meat. Use only the product that has passed veterinary control, subject the meat to a thorough heat treatment.

Trichinosis in the household

Cats and dogs can also get trichinosis. However, we must remember that a person cannot become infected from them, since the disease is transmitted only by eating infected meat. Cats can become infected when hunting for small rodents, birds, if they were carriers of Trichinella. We can infect pets ourselves by treating them with raw meat or fish.

Dogs are most often infected while hunting, especially if, after a successful hunt for a “boar”, the owner hospitably treats his pet with a hunting trophy.

Particular attention should be paid to animals when breeding fur-bearing animals. It is unacceptable to feed them raw meat that has not undergone special processing. An exception may be pork trimmings from meat processing plants, since all raw materials must be tested for trichinosis.

Symptoms of trichinosis in four-legged pets

Trichinosis in animals occurs in 2 forms:

• Acute. This form in animals is very rare and is possible only in the case of a massive invasion. It is characterized by a sharp increase in body temperature, vomiting, diarrhea, refusal of food, impaired coordination of movement. In the future, edema develops. From severe intoxication of the body with the waste products of Trichinella, the animal, as a rule, dies;
• Chronic. This form is the most common. The animal in the incubation period of the development of the disease becomes passive, appetite disappears, sometimes there may be diarrhea. There is a sharp weight loss, the animal sways when walking. The duration of the disease depends on how intensively the larvae are encapsulated in muscle tissues. After that, the clinical symptoms of the disease disappear, but the animal remains a carrier of Trichinella. Pigs that have been ill with trichinosis are significantly behind in weight gain and have a non-marketable appearance.

It is impossible to determine trichinosis in wild animals by appearance.

Until recently, there was no treatment for trichinella in animals. Although complex anthelmintic drugs have now been developed that have a detrimental effect on trichinella.

What is dangerous trichinosis for people

People most often get trichinosis because of their carelessness. Human infection with trichinosis is possible only by eating pork meat, wild boar meat, horse meat infected with Trichinella larvae and not heat treated. "It should be remembered that salting, smoking, drying, marinating meat do not destroy helminth larvae, and when frozen, they die only after 29-35 hours at minus 50-70 ° C."

The first signs of human infection with trichinosis appear, as a rule, 4-6 days after infection. The disease can develop in an erased (mild) form and in a severe form. The form of the course of trichinosis in humans depends on the number of swallowed larvae and on the state of its immune system.

The erased form of the disease is characterized by:

• Low rise in temperature up to 37.2-38°C;
• Mild muscle pain;
• There may be slight swelling, more often swelling of the eyelids.

After 2-3 weeks, the temperature suddenly rises to 40 ° C, there are severe muscle pain, severe facial swelling, headache, rash.

The severe form of the disease begins with abdominal pain, vomiting, diarrhea. Then there is severe pain in the back of the head, muscle pains increase, the temperature rises to 41 ° C .. A bloody rash spreads over the body, which becomes inflamed and begins to suppurate.

Trichinosis affects all human organs and systems: heart, lungs, liver, brain. With untimely treatment, a fatal outcome is possible. Trichinosis is diagnosed by the characteristic course of the disease, epidemiological history and enzyme-linked immunosorbent assay of blood serum to detect antibodies to trichinella.

Treatment of trichinosis is carried out with quite toxic drugs, so patients are subject to mandatory hospitalization.

Fans of shish kebabs, balyks, loin, corned beef and sliced ​​meat, raw smoked sausages and sausages should remember that "not everything is useful that got into your mouth." "By eye" it is impossible to determine whether the meat contains Trichinella larvae. Hunting tales that all meat can be disinfected by ingestion of forty degrees should not be taken as a guide to action. Only strict control when choosing meat, compliance with the rules of meat processing and cooking will make meat delicacies not only tasty, but also safe.