FOOT-AND-MOUTH DISEASE

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FOOT-AND-MOUTH DISEASE (aphthae epizooticae; synonym: aphthous fever, febris aphthosa stomatitis epidemica) — the infectious disease of a virus etiology which is characterized by a canker of a mucous membrane of an oral cavity, and also skin between fingers of hands, legs and at nails.

History. The foot-and-mouth disease of animals is known from 16 century. Diseases of a foot-and-mouth disease of people were described for the first time by the Norwegian doctor Sagar (M. of Sagar) in 1764. The possibility of infection of the person at the use of milk from a sick cow was experimentally proved in experiences of autoinfection by Gertvig, Mann and Vilen (Hertwig, Mann, Villain) in 1834. In 1898 F. Leffler and P. Frosch opened a disease-producing factor and established its ability to pass through the bacterial filter.

Geographical distribution. In the majority of the countries of the world, especially agricultural, the foot-and-mouth disease is one of the most widespread inf. diseases of animals. Only in New Zealand it is not registered at all, and in Australia the last cases were noted in 1872 that it is connected generally with geographical isolation of these countries. In the past quite often there was epizooty (see) a foot-and-mouth disease covering several continents; in 20 century of a disease I. animals are registered in the form of enzootiya (see) or the epizooty repeating usually in 10 — 12 years. To a crust, time incidence of animals of a foot-and-mouth disease in South America, Asia and the majority of the countries of Africa is very considerable. By this disease the nek-ry countries adjoining about the USSR, e.g. Iran, Turkey, Afghanistan are constantly unsuccessful.

Despite prevalence I. among animals, at people it is registered extremely seldom in the form of sporadic cases.

Etiology. Activator Ya. — the virus relating to the Picor-naviridae family, the sort Aphthovirus. There are seven serotypes of a virus of a foot-and-mouth disease — A, O, C, Asia 1, SAT 1, SAT 2 and SAT 3 possessing various immunol. properties; besides, more than 60 serovariant are known. All types and options of a virus cause a disease with identical a wedge, a picture. Serotypes And, About and With are eurysynusic around the world, a serotype Asia-1 — in the countries of Asia, and serotypes of SAT 1, SAT 2 and SAT 3 — in the countries of Africa. The animals who had I., the caused virus of one type, can repeatedly ache at infection with a virus of other type.

In the environment the virus can remain up to several weeks, and at low temperatures — up to several months. In the dried-up state survival of a virus increases. It is steady against effect of many chemical substances, but is inactivated at influence of alkalis, acids, formaldehyde; quickly perishes at pasteurization and boiling.

Epidemiology. The main source of a contagium are sick cloven-hoofed animals, first of all cattle, and also pigs, sheep, goats. Cases I are described. camels, rens, elks. Young animals are most susceptible to a foot-and-mouth disease; the disease at them proceeds hard and sometimes comes to an end with death. At animals I. it is shown by fever and damage of a mucous membrane of a mouth, nose, lips, language, on a cut there are bubbles (vesicles) turning into afta — ulcerations, and also nipples of an udder and walls of an interhoofed crack where there are also bubbles, and then ulcerations (the names «aphthous fever», «rylno-hoofed disease» from here). Virus Ya. it is allocated from an organism of sick animals with saliva, milk, excrements, urine, contents of bubbles. At cattle saliva is most infectious, and the virus begins to be allocated with saliva and milk already in an incubation interval of a disease. In 10 — 12 days from an onset of the illness allocation of a virus usually stops. In some cases a carriage of virus at the had animals can proceed till 1 year. The virus which is allocated from an organism of animals infects a laying, a forage, troughs, overalls of service personnel, the automobile. Since the virus of a foot-and-mouth disease is steady in the environment, the disease can be brought in the farms which are far from unsuccessful districts with fodder, water, objects of care of animal, dairy products, vegetables, and also the leather of animals intended for processing. Infection of people most often occurs in the alimentary way at the use of raw milk from sick animals. Infection at the use of meat is possible (including frozen) by force the slaughtered animals sick with a foot-and-mouth disease. Besides, disease I. the person can have professional character. Milkmaids, cattlemen, shepherds, employees of meat-processing plants and slaughters, veterinarians, livestock specialists are exposed to risk of infection. The virus can get into a human body through microtraumas of skin, and also mucous membranes of eyes, a nose and a mouth. Human cases are known during the work in laboratories with a virus of a foot-and-mouth disease. A susceptibility of the person to I. it is small. Reliable cases of infection I. from the sick person it is not described.

The pathogeny is substantially connected with a dermatotropnost of the activator. The virus breeds in cells of an epithelium of a mucous membrane or epidermal cells of skin that is followed by inflammatory reaction with development of primary affect — at first in the form of bubbles, and then superficial ulcerations. In the course of a reproduction of a virus in serous contents of bubbles a large number of the activator collects, to-ry then gets into blood, and there is a generalization of process. Dissimination of a virus is followed by education secondary aft on a mucous membrane of lips, a nose, language, a conjunctiva. Besides, the virus is late in skin capillaries that leads to formation of ulcerations in interdigital folds of brushes and feet. Specific afta are possible also on a mucous membrane of a stomach, intestines and generative organs.

Pathological anatomy. Morfol. changes at I. at the person are studied insufficiently. Typical for I. changes — bubbles and afta — develop in an epithelium of mucous membranes and epidermis of skin. In epithelial cells of mucous membranes there are heavy dystrophic changes, hl. obr. as vacuolar dystrophy (see). Along with it wrinkling of cells with pycnosis of kernels is described. In the subject site of a papillary layer of a derma the hyperemia develops and serous exudate accumulates. Thanks to partial preservation of cells of a basal layer on a papillary layer there is a healing of bubbles and ulcers without formation of a hem. In isolated cases I. at people can accept a heavy current. In these cases considerable spread of vesicular rashes, erosion, ulcers not only to oral cavities and a pharynx, but also in a gullet is observed. At the same time vesicles are formed in an epithelial layer, exudate accumulates under an epithelium, and the bottom of ulcers is presented by a submucosa, the surface a cut nekroti-zirutsya. Such expressed peeling is sometimes observed by exudate of epidermis that on opening the last acts from brushes together with nails as a glove. According to

S. I. Ratner and sotr. (1956), at the long course of a foot-and-mouth disease under an epithelium of mucous membranes in the field of the dried-up erosion limfoplazmotsitarny infiltrates are found. The endothelium of vessels the bulked-up, connective tissue layer is hyalinized. On opening increase in the sizes of heart due to expansion of his cavities usually is found. The myocardium is flabby, a clay look on a section. Microscopically serous myocarditis comes to light.

Immunity. The postponed disease leaves strong, but short (for 1 — 1V2 years) immunity of strictly type-specific character.

Clinical picture. Standard wedge, classifications I. does not exist. It is possible to allocate the following a wedge, forms of a disease: skin, mucous and skin and mucous. At a skin form not numerous ulcerations are found only on skin, as a rule, in the field of entrance infection atriums; this form meets more often at professional infection. At a mucous form the main display of a disease — aphthous stomatitis. Most often the skin and mucous form meets, edges also an eye, and also skin is characterized by damage of a mucous membrane of an oral cavity, it is preferential in fingers.

The incubation interval — 2 — 12 days (it is rare to 15), is more often than 3 — 5 days. I., as a rule, begins sharply with a fever, a headache, weakness, an indisposition, an ache in muscles, bones, a waist, temperature increase to 38 — 39,5 °; cases of a gradual course of a disease are described. In 1 — 2 day dryness and a burning sensation in a mouth joins, nek-ry patients have, besides, a photophobia, and sometimes burning at an urination. On lips, language, a hard and soft palate, a mucous membrane of cheeks against the background of a sharp hyperemia and hypostasis appear small (to dia. 2 — 4 mm) oval bubbles, filled with light transparent contents, a cut quickly become rather turbid-yellow. Vysytsaniya are especially numerous at the edges of language and on its tip. In 1 — 2 days bubbles burst, and on their place are formed painful, irregular shape, the bright red superficial ulcerations sometimes merging among themselves (see Afta). After opening of bubbles body temperature, as a rule, decreases, however the health of patients worsens. They feel pain during the swallowing, plentiful salivation appears (to 4 — 5 l a day), language considerably increases in sizes, the speech becomes muffled, swell up a little and there are painful regional limf, nodes. Ulcerations on a mucous membrane of an oral cavity, lips, language begin to live usually in 3 — 5 days, without leaving hems. Bubbles, also afterwards ulcerating, can appear on a mucous membrane of a nose, a vagina, an urethra, on a conjunctiva, a back wall of a throat. Except damage of mucous membranes, most of patients has bubbles on skin. Their most characteristic localization — skin between fingers of hands and legs, and also at the basis of nails. In the field of brushes and feet hypostasis, burning, feeling of crawling of goosebumps, an itch are sometimes noted. In some cases nails descend afterwards. At the same time at most of patients temperature is normalized, the health improves and there comes the period of reconvalescence proceeding 10 — 15 days. However at nek-ry patients perhaps repeated rash of bubbles on mucous membranes and skin, and the disease gains long character. In cases of a heavy current I. appears the spotty father - leznaya (sometimes hemorrhagic) rash on a neck, a breast, a back. At adults damage of internals is clinically shown very seldom, at children at I., proceeding usually heavier, than at adults, the dispeptic phenomena — vomiting, a frequent liquid chair are quite often noted (sometimes with impurity of blood).

Except an acute current I., cases with a long (chronic) current are described (to 1V2 years). And in later terms of a disease of an enanthesis have an appearance not of bubbles, and hillocks, to-rye resolve with the subsequent peeling of skin over them.

Accession of consecutive infection (it is observed more often at the children and elderly people weakened by the previous diseases) can be followed by development of pneumonia, sepsis. In rare instances the foot-and-mouth disease is complicated by myocarditis.

The diagnosis is established on the basis of data epidemiol. the anamnesis (contact with sick animals, the use of raw milk) and a wedge, pictures (a combination of an acute onset of the illness, fever, intoxication to aphthous damage of a mucous membrane of an oral cavity and an ulceration of skin in the field of interdigital folds and nail phalanxes). In blood in the heat of a disease the eosinophilia, at a part of patients — a leukopenia is noted.

Laboratory diagnosis. For allocation of a virus Ya. from patients investigate a discharge aft, and carry out blood or urine biol. test on susceptible laboratory animals (Guinea pigs, a krolchata, little mice) or in culture of cells. Guinea pigs easily catch at intradermal administration of virussoderzhashchy material in the plantar surface of back pads; on to-rykh primary defeats in a look aft appear in 24 — 48 hours Myshat-sosunov and krolchat infect subcutaneously or intraperitoneally. In 2 — 5 days after inoculation their paresis and paralyzes are developed, and animals perish.

For allocation of a virus Ya. use primary tripsinizirovannye cultures of cells of kidneys of calfs or pigs, to-rye infect with contents aft and maintain in the thermostat at t ° 37 °. The cytopathic effect comes in 20 — 24 hours. By means of specific serums find and identify types and options of a virus Ya. in reaction of binding complement (see) and precipitation tests in agar gel (see. Serological researches).

Recently for diagnosis I. began to apply an immunoenzyme method and an immunosorbentny method marked enzyme of antibodies (see. Enzyme-immunological method). These methods allow to find and carry out quantitative definition of antibodies and antigens.

The differential diagnosis is carried out with aphthous stomatitis (see). The last meets at small children more often, is not followed by high temperature, is characterized by damage only of a mucous membrane of an oral cavity, other mucous membranes and skin remain intact. At aphthous stomatitis, unlike I., there is no raised sialosis, an ulceration deeper, ulcers never merge among themselves, their bottom is covered with a whitish plaque; the eosinophilia in blood does not happen.

In some cases it is necessary to carry out the differential diagnosis with chicken pox (see), however at it bubbles are located with hl. obr. on a trunk, sometimes on a pilar part of the head, but never happen on brushes and feet. Bubbles on a mucous membrane of an oral cavity and in a pharynx at chicken pox almost never ulcerate, there is no raised sialosis.

The foot-and-mouth disease is differentiated with a mnogoformny exudative erythema (see the Erythema exudative mnogoformny), for a cut emergence sharply limited, enough big (to 3 — 5 cm) bright red spots or papules (small knots) not only on brushes and feet, but also on extensor surfaces of forearms and shins, around large joints, on a face is characteristic. Damages of mucous membranes can not be, sometimes there are bubbles on a mucous membrane of an oral cavity and lips, but they larger, than at I., and after their opening the bleeding erosion are formed.

Sometimes there is a need of carrying out the differential diagnosis between I. and Bekhchet's syndrome (see Bekhchet a disease). It must be kept in mind that similar with I. damages of mucous membranes and skin are caused by Koksaki's virus A1b (see Koksaki-vi-rusnye of a disease).

Treatment. Patients I. it is necessary to hospitalize and isolate before the termination of acute displays of a disease, but not less than for 14 days (beginning from its beginning). Causal treatment is not developed. Careful patient care and the corresponding diet is of great importance (fractional food liquid food of 5 — 6 times a day). Locally apply rinsing of an oral cavity one of the following solutions: 3% solution of hydrogen peroxide, 0,01 — 0,1% of potassium permanganate, 0,1% of Aethacridinum of a lactate (Rivanolum); use also infusion of a camomile. Afta process 2 — 5% solution of silver nitrate or concentrated (1 — 3%) solution of potassium permanganate. During healing aft it is recommended to grease their vinylother,-rotolinom, with oil of a dogrose or a sea-buckthorn. At defeat of a conjunctiva appoint washings of eyes of 2% solution boric to - you and an instillation of 5 — 6 times a day in both eyes of 30% of solution of Sulfacylum-natrium. At heavy disease, especially at children, at accession of consecutive infection prescription of antibiotics and disintoxication therapy is reasonable.

Forecast. The foot-and-mouth disease, as a rule, proceeds is good-quality and comes to an end with an absolute recovery in 2 — 3 weeks.

Prevention. By the most effective method of prevention I. at people its elimination among animals is. The complex a dignity is for this purpose carried out. - vt. actions (vt. supervision of the imported animals, immunization of healthy animals, a quarantine etc.). The persons who are looking after sick animals shall be trained in rules of personal and production hygiene, are provided with overalls. For the purpose of the prevention of infection through milk and meat of animals, sick and suspicious on a disease, sale of these products is forbidden; mhgo goes for industrial processing, milk will be pasteurized at a temperature of 85 ° within 30 min. or boiled within 5 min. It is important a dignity. - a gleam, work among the population of districts, unsuccessful on a foot-and-mouth disease, in particular an explanation of need of obligatory boiling of milk not less than 5 min.

Bibliography: B about y to about A. A. and Shue -

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S. Ya. Gaydamovich, t. 1 — 2, M., 1982; Rat-ners. And. and d river. Case of a long course of a foot-and-mouth disease, Klin, medical, t. 34, No. 7, page 70, 1956; P e p e p X. The foot-and-mouth disease, the lane with is mute., M., 1971; Rudnev of G. P. Antropozoonoza, M., 1970; The Management on a zoonosis, under the editorship of V. I. Pokrovsky, page 90, JI., 1983; With yu r and V. N. N and d river. Laboratory diagnosis of viral diseases of animals,

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