Smallpox refers to an infectious disease of chickens. Pigeons and turkeys are most susceptible to it.

Chickens are in 3rd place. Smallpox is caused by a virus. There are 2 types of chicken pox: skin and diphtheria. At the first, specific ulcerative lesions (pockmarks) develop on non-feathered parts of the body. The diphtheria form gives lesions on the mucous membranes of the mouth and esophagus. The incubation period (when symptoms are still difficult to notice) lasts approximately 2 weeks.

Symptoms of the disease

With a cutaneous form, nodular ulcers appear on the crest, earrings, eyelids. With the diphtheria variety, yellowish wounds appear on the mucous membranes of the mouth, esophagus, trachea. All this is accompanied by shortness of breath. Chickens lose their appetite, they do not gain weight well. Layers stop laying. The active period of the disease usually lasts up to 4 weeks, but if the outbreak is strong, then 2 times longer. The mortality rate is low, but with severe damage it reaches 50%.

How smallpox is transmitted

The pathogen is transmitted by contact; it must get into the wound on the skin. The main source of infection is a sick and recovered bird. In smallpox scabs, the pathogen lives up to 2 years. The virus is also transmitted by insects and people on their clothes and hands during the vaccination period. An infected female can transmit the virus to her offspring through eggs. The disease affects all chickens, regardless of age. The virus acts in the same way on adults and chickens.

Smallpox treatment

Smallpox is not treated, only vaccination is carried out. The presence of the disease is confirmed in laboratory conditions by isolating the pathogen. The diphtheria form of smallpox without appropriate tests can be easily confused, for example, with viral laryngotracheitis.

The smallpox vaccine is obtained from a chicken embryo and contains a natural, rather strong virus. It must be applied strictly according to the recommendations, otherwise you can infect all the livestock. Chickens can be vaccinated at one day old or 4 weeks old pullets. The vaccine should be purchased from specialized institutions where it is stored correctly. Otherwise, the effect may be zero.

Prophylaxis

Bird pox (VARIOLA)

Smallpox (smallpox - diphtheria, pips, pseudo-membranous tonsillitis, malignant catarrh, yellow scurvy, cutaneous tubercle, contagious epithelioma, diphtheria, etc.) of birds is a contagious disease characterized by the formation of specific smallpoxes on the skin and diphtheroid lesions of the mucous membranes of the respiratory tract and the conjunctiva.

History reference. Guzard was one of the first to describe smallpox in chickens (Huzard, 1778). Bollinger (Bollinger, 1873) discovered specific inclusions in the cells of tissues of birds with smallpox. Later, it was found that these inclusions are clusters of tens of thousands of virions, and they called them "Bollinger bodies". Before the discovery of the causative agent of smallpox, skin (smallpox) and diphtheroid (diphtheria) forms of its manifestation were defined as two independent diseases. Only after 1902, when the Russian scientist F.P. Polovinkin and the German researchers E. Marx and A. Sticker (E. Marx and A. Sticker) established that the causative agent of smallpox in birds is a virus. T. Garnwath (T. Garnwath, 1907) and others proved that pathological material taken with smallpox can cause disease in birds, characterized by damage to the mucous membranes, and the material of the latter - a smallpox rash on the skin. E. Marks and A. Sticker, and then Juliusberg (Julmsberg, 1904) and others noted the difficulty of filtering the virus as a result of firm fixation on the filter. It was possible to filter the virus only through the Berkefeld V filter, and Findlay (1928) through the Chamberlain filter L. N. V. Likhachev and S. S. Kasatkevich (1935) established the possibility of virus purification by diffusion through a column of 10% gelatin.

A. Borrel (A. Borrel, 1904). discovered in the skin of a bird sick with smallpox special little bodies, called at the beginning strongyloplasmas, and then elementary particles or Borrell's little bodies (virions). This discovery was confirmed by other researchers, and it acquired great importance in the diagnosis of smallpox. But, despite the widespread prevalence of smallpox in the countries of the world among birds of many species, there is still no consensus on the difference in the causative agents of smallpox for birds of different orders. It is firmly established that the chickenpox virus and the smallpox virus of pigeons exist independently, and Kikut and Gollub (W. Kikuth and N. Gollub, 1932) also identified the canarypox virus. In 1933 this was confirmed by Burnet, Herzberg and others.

Etiology. Smallpox affects birds of the suborder chicken, the order of pigeons and the order of passerines, the causative agents of which are chickenpox virus (Virus borreliota gallinorum), pigeon pox virus (V. b. Columborum) and canarypox virus (V. b. Fringillorum), respectively. Some researchers (Van Rooyen, 1954; A. Maug, 1960, and others) are trying, due to some peculiarities, to single out the turkeypox virus into a special group. All these viruses belong to the group of large epitheliotropic poxviruses, combined on the basis of biological properties characteristic of all pathogens of smallpox. However, in terms of pathogenic and immunogenic properties, they differ from each other, which allows them to be distinguished into the indicated varieties. Individual strains of the listed viruses can be monopathogenic in relation to birds of the indicated suborder and orders, as well as bipathogenic (this is characteristic of strains of the pigeon pox virus in relation to birds of their order and suborder - chicken proper) and trypathogenic, which is typical for many strains of canarypox virus, although intense immunity from them and is created, as a rule, only against the canarypox virus. Smallpox viruses of pigeons and chickens of bipathogenic strains create mutual cross immunity in most birds of the corresponding order and suborder, but usually less intense in birds not of their own order or suborder (Table 1).

Table I Immunobiological properties of avian pox viruses

Legend: - there is no visible follicular reaction, does not cause the formation of immunity; + follicular reaction is poorly expressed, the formation of weakly expressed immunity; ++ follicular reaction is well expressed, the formation of moderately pronounced immunity; -f -J- + - the dollicular reaction is strongly pronounced, the formation of a tense and long-term immunity.

The smallpox virus, isolated from turkeys, is similar in its properties to the bipathogenic strains of the chickenpox virus.

Some microorganisms, more often from the group of cocci, Bact, contribute to the onset of the disease and aggravate its course (especially of the diphtheroid form). necrophorus, etc.

The sizes of fowlpox viruses vary in the range of 180-350 mm; in smears processed by the method of silvering, virusoscopy through the immersion system of a light microscope, their value is usually about 250 mmk. Wittmann (1958) discovered a precipitating antigen in the virus. From it, specific precipitating antibodies are formed in the body, which can be detected in blood serum by the reaction of diffusion precipitation (RDP) in an agar gel.

Virus resistance. The virus, released (purified) from the tissue, is not resistant to physical factors and chemical agents, and located in tissue cells (which is more often in natural conditions) remains viable for a relatively long time. Smallpox viruses survive for a long time when dried and frozen. This characteristic of their property is an important factor contributing to the long-term preservation of viruses in natural conditions. High temperatures, acids, sun rays and putrefactive microorganisms have a detrimental effect on viruses, accelerating the decay of tissues and the destruction of virus-containing cells. In tissues, when heated to 100 °, the virus dies in 5 minutes, up to 80 ° - in 30 minutes, up to 60 ° - in 3 hours; at a temperature of 37-38 ° and good aeration, the virus persists for eight days; in water at 56 °, the virus dies in 30 minutes. In a finely ground tissue suspension at a temperature of 0 °, the virus remains viable for three months, and when stored in a mixture of phosphate-buffered saline with glycerin (at pH 6.8) for 20 months, at 7 ° for eight months, and at 30 ° - three months. At temperatures below -15 ° in the dry epithelium, the virus remains viable for 15 years. In dry epithelium at a temperature of 0-6 ° the virus persists for eight years, at 18-22 ° for six months, and a virus dried in a vacuum under the same conditions - up to two years or more.

In an acidic environment (pH 3), the virus dies in an hour. In 5 minutes, the virus is inactivated by 1% solutions of acetic acid, mercuric chloride and caustic potassium. Ethyl alcohol (70-95 °) inactivates the virus in 10 minutes, and 50 ° at 20-26 ° in 30 minutes; A 3% phenol solution, when exposed to a virus in a dry epithelium at 20 ° C, inactivates it in 30 minutes, and 1-2% solutions in 90 minutes. Formalin solution 1: 500 inactivates the virus in dry epithelium in 8 hours.

A.A. Rahimov (1962) found that in contaminated outdoor areas in Azerbaijan in summer and autumn, the chickenpox virus remains active at a temperature of 20-29 ° C and a relative humidity of 26-48% for 143 days, and indoors at 19 -25 ° and relative humidity within 24-36% -158 days. In summer, the virus dies in 6 hours from sunlight in areas not contaminated with droppings, and in areas polluted at 24-33 ° and a relative humidity of about 26%, it is inactivated after 11 hours. On the surface of down and feathers outside the house at a temperature of 3-30 ° and a relative humidity of 28-48%, the virus remains virulent for 195 days, and on the surface of the eggshell at 5-24 ° and a relative humidity of 28-60%, no less 60 days. In non-chlorinated tap water, the virus remains virulent for 66 days, and in river water at 18-21 ° - 76 days.

Epizootological data. Smallpox poultry can get sick in all seasons of the year, but more often get sick and more difficult to transfer the infection during the "molt" period, in autumn and winter, depending on climatic conditions and maintenance. Young animals and decorative birds are especially susceptible to smallpox. In an adult bird, mainly in pigeons, a skin form is more often noted, and in young animals a diphtheroid or mixed one. This is due to the fact that in an adult bird the virus mainly enters the body through damaged skin, and in young animals through the mucous membrane of the oral cavity. In the warm season, as well as in countries with a hot climate, smallpox is more often recorded in birds, and in winter and in countries with a cold climate, mucous membranes are affected in birds. The frequent illness of birds in early spring can be explained by vitamin deficiency and a violation of mineral metabolism, which lowers the body's resistance and increases the possibility of virus penetration into the body even through the intact mucous membrane of the initial part of the digestive tract (especially with vitamin A deficiency).

Piglets may be susceptible to certain virulent strains of chickenpox virus. Man does not get sick with smallpox.

The main source of the smallpox virus is sick birds and virus carriers, which disperse it into the external environment with falling off epithelium, crusts, films, feces and discharge from the nasal and oral cavities and from the eyes. The carriers of the virus can be both domestic and wild birds, as well as rodents and blood-sucking insects. So, in the body of the Persian tick, which was pumped by the blood of chickenpox patients, the virus lasts 30 days, in the body of a bug - 35 days, ornithodorus tick - 97 days, in flies - 20 days, and in mosquitoes and mosquitoes - 210 days.

Infection occurs when a healthy bird comes into contact with a sick bird and a virus-carrying bird, as well as through virus-contaminated eggs, feed, water, equipment and clothing of service personnel. The virus can also spread by aerogenic means.

Smallpox outbreaks are usually enzootic, but epizootics are sometimes noted. Poultry sickness on the farm usually lasts about 6 weeks.

In a sick bird, egg production decreases 5 times or more and slowly recovers after recovery; the hatchability of chickens decreases not only during illness, but also for a considerable time after the chickens have been ill. Often, only about 20-25% of the chicks are hatched. A bird that has had smallpox loses its natural resistance for a long time and, as a result, becomes more sensitive to other diseases.

The pathogenesis is determined by the pronounced epitheliotropy of smallpox viruses. Once in the epidermis or in the epithelial layer of the mucous membrane, the virus multiplies, forming smallpox foci, the severity of which depends on the resistance and reactivity of the organism and on the virulent properties of the strain.

From the primary smallpox foci, the virus enters the bloodstream and internal organs within a day. I.G. Grinets, Yu.F. Borisovich and L. S. Ageeva (GNKI, 1963) found that virulent strains of chickenpox virus, entering the blood and hematopoietic organs of a susceptible organism, strongly affect the cells of the peripheral blood and reticuloendothelial system, affecting bone marrow cells up to the formation of necrosis, which causes significant dysfunctions of the blood and hematopoietic organs. The virus, which has multiplied in blood cells and the endothelium of blood vessels, is transferred to other, mainly unaffected areas of the skin and mucous membrane, where new foci of smallpox appear. Within 24-48 hours after skin infection of a bird, the virus can be detected in the spleen, lungs, liver, gall bladder, heart and kidneys, where it causes dystrophy of parenchymal cells and changes in vascular endothelial cells.

Usually, the smallpox process has a pronounced generalized character with the greatest damage to the epidermis of the skin, epithelium of the mucous membranes and internal organs, changes in which are characterized mainly by hyperplasia of epidermal cells with the appearance of Bollinger bodies in their plasma. In chickens, simultaneously with the smallpox process developing in the skin, there is an intense infiltration of the subcutaneous tissue with lymphoid and pseudo-eosinophilic cells. The diphtheroid process begins more often on the mucous membrane of the oral cavity, from where it spreads to the mucous membrane of the nose, larynx and other parts of the body. It can start on its own without skin lesions, but is more often secondary to the generalization of smallpox. The most dangerous are secondary lesions of the mucous membrane of the larynx, since due to the formation of diphtheroid films in the bird, breathing and swallowing food becomes difficult, which leads to exhaustion and weakening of the body, and sometimes causes blockage of the larynx and death of the bird from suffocation.

Pathological changes in diphtheroid and mixed forms of smallpox are the result of the combined action of the virus and secondary microflora. The influence of the latter is often noticeable even when the smallpox process has ended and there is no longer a virus in the affected areas. In this case, the remaining signs of "diphtheria" (in the absence of the virus) often lead to diagnostic errors. If the smallpox process is not very complicated by the secondary microflora, the diphtheroid films are rejected and the mucous membrane regenerates, and in the case of pronounced complications, deep cicatricial ulcers do not heal for a long time. Usually, the smallpox process in chickens ends in 17-45 days after the onset of the disease.

Symptoms of the disease. The incubation period depends on the virulent properties of the virus, the way it enters the body, as well as on the age and physiological state of the bird and lasts 4-8, less often 10-15 days. The disease usually proceeds subacutely, but often takes on a chronic and less often acute course. There are cutaneous (the most typical form), diphtheroid and mixed forms of smallpox. The latter happens most often, but one of the forms is sure to prevail. Sometimes the so-called latent forms of smallpox are observed with damage mainly to the internal organs. This form is more often observed in birds with reduced resistance and reactivity of the organism, as well as in birds of the order of passerines, in particular in canaries. Some researchers are trying to isolate from the initial stage of the diphtheroid form of smallpox into a separate form, the so-called catarrhal form according to one clinical sign not quite characteristic of smallpox, more often observed with mixed infection or abortive course of the diphtheroid form of smallpox.

Rice. 1. Smallpox lesions on the head of a rooster (according to VN Syurin, 1965).

With cutaneous and mixed forms of smallpox, usually on the 4-5th day after infection in chickens on the skin at the base of the beak, eyelids, on the crest, beards and other parts of the body, round, first pale yellow, and then reddish spots appear, gradually turning into warty epitheliomas (growths), often merging with each other and sometimes reaching 0.5 cm. After a few days, their surface becomes rough, dark brown in color (Fig. 1).

Pockmarks are formed 7-9, sometimes 14 days. At their base, inflammation develops and hemorrhages appear. The pockmarks are covered with crusts, which, in the absence of complications, disappear within 7-10 days without leaving noticeable scars. If the scab is removed, then under it is noticeable an accumulation of serous-purulent exudate covering the granulating surface. After a rash of primary pockmarks, on the 17-19th day after infection in chickens, sometimes the phenomenon of a secondary smallpox process is observed on previously unaffected areas of the skin, more often in the featherless areas of the head, legs, wings and near the cloaca. Sometimes smallpox in chickens is accompanied by the development of keratitis, and with complications by secondary microflora, panophthalmia.

The general condition of the bird is depressed, feathers are ruffled, appetite is reduced or completely absent.

With diphtheroid and mixed forms on the mucous membranes of the oral cavity, tongue, nose, larynx, trachea, bronchi, accessory cavities, sometimes under the cuticle of the stomach and on the intestinal mucosa, a rash appears in the form of whitish, opaque, several raised nodules. They quickly spread and, increasing in size, often merge with each other, become yellowish and contain a curdled consistency of necrotic tissue in the form of films connected to the submucosa. If these diphtheroid pseudomembranes are removed, bleeding erosions are formed, and when they are contaminated with microbes, a purulent process develops. Diphtheroid films make breathing difficult, so birds have an open mouth and make whistling or wheezing sounds when they breathe.

In pigeons, the cutaneous form of smallpox usually predominates with localization of smallpox lesions along the edges of the eyes, at the base of the beak and on the legs. Erosions and ulcers are sometimes visible on the oral mucosa. Sometimes iritis and cataracts are noted.

A favorable outcome of the disease can only be in those birds that were healthy and well developed before the disease, were kept in exemplary sanitary and zoohygienic conditions and in which the cutaneous form of smallpox is not complicated, and smallpox lesions are localized only on the head. Usually, however, the prognosis is unfavorable, since it is unprofitable to keep sick birds.

The percentage of bird deaths largely depends on the age and conditions of keeping. In some poultry houses, 10 to 70% of birds die. A particularly high mortality occurs among young animals with diphtheroid and mixed forms, complicated by secondary microflora. Among pigeons, mortality ranges from 8%, but sometimes under poor conditions it rises to 25-30% among adult birds and up to 100% among young birds.

Pathological changes are determined by the form and duration of the course of the disease and correspond to its clinical symptoms. In cutaneous and mixed forms, smallpox lesions are more often localized on the skin and mucous membranes of the oral cavity and upper respiratory tract, larynx and trachea, as well as bronchi, sometimes on the mucous membrane of the pharynx, esophagus and intestines (duodenum, blind and rectum). In the diphtheroid form, the mucous membrane of the trachea, bronchi and accessory cavities is affected much more often. Sometimes smallpox lesions are found under the cuticle of the stomach, on the mucous membrane of the esophagus and intestines. If the mucous membrane of the air sacs is involved in the process, it becomes cloudy, a mucopurulent exudate appears in the nasal cavity, and if the infraorbital sinus is affected, then it, like the trachea, is filled with a yellowish-brown curdled-crumbly mass. As a rule, the conjunctiva and eyes are affected. In some birds, skin lesions are weak, but changes in the internal organs are significant and are characterized by small yellowish foci in the liver, pulmonary edema, punctate hemorrhages on the epicardium and serous membranes. The intestinal mucosa is stained and loosened, and sometimes it is riddled with small hemorrhages. In the chronic course of smallpox, the liver, kidneys and heart muscles are degenerated, the spleen is slightly enlarged, swollen. The bodies of the fallen birds are emaciated. In cases where there is no smallpox rash, exhaustion and degeneration of individual organs and muscles are the only pathological changes that characterize such a course of smallpox.

On histological examination, smallpox lesions are characterized by hyperplasia of epithelial cells and hydropic dystrophy with moderate hyperkeratosis, as well as thickening of the epidermal layer due to increased multiplication of its cells. In the subcutaneous tissue, there is an expansion of blood vessels, lymphoid-pseudosinophilia and a histiocytic cell reaction. With a primary lesion of the mucous membrane, signs of smallpox epithelioma are found, and later the phenomenon of diphtheroid inflammation.

In the plasma of epithelial cells affected by the virus, Bollinger bodies are found, the finding of which confirms the etiology of the disease. With an increase in the size of inclusions, the destruction of the nucleus and cell death occurs. On the basis of histological examination, smallpox is differentiated from A-avitaminosis: with smallpox, the pathological process is localized mainly in the squamous stratified epithelium.

The diagnosis is made on the basis of the analysis of clinical and epizootic data, pathological and histological changes and laboratory studies (viroscopy, RDP, bioassays with the isolation and identification of the virus, if necessary, on developing chicken embryos, tissue cultures, chickens and pigeons, using neutralization and hemagglutination reactions, luminescent microscopy, etc.).

Given the relevant epizootic data and the scalp lesions characteristic of smallpox, it is not difficult to diagnose smallpox. If lesions are found only in the oral and nasal cavities or in internal organs, it is necessary to carefully examine all birds to identify at least a few with characteristic signs of the disease and make smears to detect smallpox virions in them. In doubtful cases, it is necessary to put a bioassay and make smears from fresh pockmarks that have not yet been complicated by secondary microflora.

Rice. 2. Smallpox folliculitis on the right shin of a chicken on the 8th day after rubbing the pigeon pox virus into feather follicles - a positive reaction to a dry embryo vaccine (according to Yu. F. Borisovich, 1968).

Rice. 3. The button part of the chorioallantoic membrane of the chicken embryo, affected by the smallpox virus. Individual pockmarks are clearly visible (according to Yu. F. Borisovich and K. M. Islentyeva, 1967).

For the production of bioassays, they infect healthy chickens that have not been previously immunized against smallpox and have not had smallpox. The suspension is rubbed with a sterile brush into the slightly scarified surface of the ridge and into the follicles of the lower leg immediately after plucking out the feathers. If the test material contains chickenpox virus, then on the 5-7th day after infection, characteristic pockmarks appear on the ridge, and folliculitis, typical for smallpox, appears on the lower leg.

By examining smears from the material of fresh smallpox lesions (after processing them by the method of silvering), virions can be detected. The presence of many characteristic virions in smears ("scattering" type) confirms smallpox; their absence does not give grounds for excluding this disease.

The smallpox virus in epitheliomas can also be detected electronically by the method of adsorption of the virus from the test material onto the collodion film. In chickenpox, both immature bubble-shaped "viral particles" ranging in size from 60 to 200 mmq and typical brick-like and oval mature virions are simultaneously detected. With negative contrasting of virions, filamentous structures are visible.

When setting up a bioassay, it should be remembered that a vaccine strain of pigeon pox virus can be isolated from a bird previously immunized against smallpox with a live pigeon virus vaccine, which causes a similar, but more benign inflammation of feather follicles in chickens without the formation of necrotic crusts (Fig. 2) and diphtheroid lesions of the mucous membranes. In this case, you need to isolate the virus in its purest form and identify it. For this, developing chick embryos are infected by applying material to the chorioallantois (Fig. 3), day-old chicks by injecting material under the skin in the area of ​​the inner side of the wing (after the introduction of the pigeon pox virus, the reaction is negative), and pigeons, rubbing the suspension into freshly nude feather follicles of the breast area muscles, etc.

Sometimes the diagnosis can be confirmed by RDP according to the method of Giordani and Chubb (1962), somewhat modified by G.A. Lezhava (GNKI, 1964). When setting this reaction, it should be borne in mind that precipitating antibodies in chickenpox appear in the blood serum usually between 11 and 36 days after the onset of the disease, mainly in older birds. The blood serum of a bird infected with a highly virulent strain of the virus gives a more pronounced RDP. But we must also remember that the precipitating serum of convalescents is often weakly active, and in 15% of chickenpox patients it is not at all possible to establish the presence of precipitating antibodies. Therefore, it is better to set the RDP with a knowingly active hyperimmune anti-smallpox serum obtained from males and the studied pathological material in the form of an antigenic suspension with a number of necessary controls. A positive reaction of precipitation (macro- or microvariants) confirms the diagnosis of smallpox, and a negative one still does not give the right to exclude smallpox ethnology of the disease.

Differential diagnosis. With smallpox, vitamin A deficiency must be excluded, infectious laryngotracheitis chickens, infectious bronchitis of chickens, infectious rhinitis of chickens, trichomoniasis in pigeons, thrush in chickens and pigeons, aspergillosis, candidiasis, respiratory mycoplasmosis, cholera and some other infectious diseases that can sometimes be mistaken for an atypical form of smallpox or, which is more common when they occur simultaneously with smallpox.

Avitaminosis A excludes a negative bioassay, as well as histological data, which show that, in contrast to smallpox lesions, avitaminosis mainly affects the cylindrical epithelium of the mucous glands of the oral cavity, throat, tongue, esophagus, goiter and trachea, instead of which keratinizing flat multilayered etithelium grows and the normal state of the mucous glands and ciliated epithelium is disrupted; uric acid appears in the kidneys, which is then deposited under the epicardium and under the liver capsule. In the affected cells with avitaminosis A, there are also no intraplasmic Bollinger bodies.

Infectious laryngotracheitis of chickens is excluded by a negative “cloacal” test in chickens susceptible to laryngotracheitis, a precipitation reaction and a neutralization reaction in chickens, developing chick embryos and tissue cultures of chick or duck embryos, as well as the absence of a follicular reaction in chickens in a bioassay.

Infectious bronchitis of chickens, which has just appeared in the poultry farm, is excluded, given the lower virulence and the absence of typical smallpox lesions on the skin and mucous membranes. The specificity of the virus is determined by cross-checking the immunity of diseased chickens. In addition, chickens, mainly of brooding age, get sick with bronchitis.

An infectious rhinitis is excluded by staging a bioassay, viroscopy of the affected areas and cross-checking of immunity in recovered birds, as well as the absence of Bollinger bodies in the pathological material.

Cholera (pasteurellosis) and other infectious diseases of viral and bacterial etiology are excluded by setting appropriate bioassays and conducting bacteriological and histological studies of pathological material from sick birds.

Thrush, scab, aspergillosis and candidiasis are excluded on the basis that microscopy of pathological material in smallpox does not contain spores and mycelium of the corresponding fungi (and vice versa).

Mycoplasmosis and trichomoniasis, in contrast to smallpox, are characterized by negative results of follicular bioassay on poultry susceptible to smallpox and a precipitation reaction with anti-smallpox hyperimmune serum.

Immunity is characterized by the appearance of virus-neutralizing and precipitating antibodies in the blood serum of birds (signs of the presence of humoral immunity) and the formation of tissue immunity. Immunobiological restructuring of the organism of an infected bird begins from the first day the pathogen of smallpox enters it, but fully immunity is formed only after 3-4 weeks.

An adult, recovered bird with good body reactivity is immune for three years. After a single vaccination of chickens with the pigeonpox virus, immunity is less intense and less prolonged. For example, in young animals it remains up to 3-5 months, and in an adult bird up to 6-8 months. Moreover, if to create immunity in chickens using the chickenpox virus it is enough to cause inflammation of 2-3 feather follicles, then to create immunity with the smallpox virus of pigeons it is necessary that the inflammatory reaction spreads to at least 15-20 follicles when a virus is applied to them. titer ID50 not less than 10 ~ 4-10 ~ 5. Thus, the duration and intensity of immunity in a vaccinated bird largely depends on the immunogenicity of the virus strain used, the age of the bird, its reactivity and methods of immunization. The method and scheme of immunization of birds in the USSR are regulated by the current instruction on the use of dry embryo-virus vaccine from a pigeon strain (1968).

Treatment. There are no effective specific remedies for the treatment of birds with smallpox. V.V. Vinogradov obtained a preventive and therapeutic effect from the use of anti-smallpox gamma globulin after its introduction to a bird in a dose of 0.3 ml under the skin. According to the legislation, it is recommended to kill a bird sick with smallpox and an emaciated bird. Only in some cases is a valuable bird with mild smallpox lesions isolated in a separate room and treated symptomatically. Intramuscular injections of epinephrine 1: 10,000 are recommended with the addition of potassium iodide at a concentration of 0.07% to drinking water or, even better, when given in a mixture with milk.

In treatment, iodine preparations are preferred. After softening smallpox lesions on the skin with ointments, oils or glycerin and removing peeled off crusts, it is recommended to lubricate the ulcerative surfaces with tincture of iodine (you can also use a 3-5% solution of potassium permanganate or burn these places with lapis, undiluted creolin, tar and other disinfectants). The mucous membrane, after removing the diphtheroid overlays from it, is daily lubricated with a mixture consisting of 10% tincture of iodine and 90% glycerin (some authors recommend using this mixture in equal proportions, as well as a 3% solution of hydrogen peroxide, 0.5-2% - solutions of chloramine or dichloramine). The nasal cavity and conjunctiva are irrigated with 2-3% boric acid solutions daily after removal of the accumulated mucous secretion and washing with warm water until the inflammatory process stops.

Birds in which smallpox is complicated by a secondary bacterial infection are prescribed antibiotics (penicillin, terramycin, tetracycline, oxytetracycline, etc.). Sick birds improve the conditions of keeping and feeding. They give soft food in crushed form, greens, mashed carrots, alfalfa flour and other vitamin supplements are introduced into the diet. The inclusion of antibiotics (erythromycin, etc.) in the diet, as well as furazolidone, helps to reduce the mortality of the bird and accelerate its recovery.

Prevention and control measures. The success of the fight depends on well-organized, taking into account the specifics and characteristics of the disease, preventive veterinary and sanitary measures, timely diagnosis and correctly taken measures for the fastest elimination of smallpox. All anti-smallpox measures in the USSR are regulated by the current instructions for the fight against smallpox of birds (1970) and the main provisions of the Veterinary Regulations of the USSR (1967).

In smallpox-free farms, it is necessary to strictly carry out veterinary and sanitary measures aimed at preventing the introduction of the pathogen of smallpox into it and increasing the resistance of the poultry organism. Especially carefully these measures should be carried out by persons working on the farm and having birds for personal use. All poultry brought into the farm must be quarantined for a period of 30 days. In quarantine, the bird is systematically monitored by a veterinarian. When a bird suspicious of smallpox appears, the entire bird is carefully clinically examined, and pathological, viraloscopic, and, if necessary, a biological study of material from this bird is carried out to clarify the diagnosis.

The economy (farm, branch or settlement), in which smallpox is established, is declared unfavorable and thorough disinfection is carried out in it. The import and export of poultry, poultry products, feed, etc. are strictly regulated. A sick, weak and emaciated bird is killed, and a clinically healthy bird is immunized in accordance with the current instructions. A bird that falls ill within 20 days after vaccination (from among the "incubators") is also killed. Immunize all clinically healthy birds and those belonging to individual owners in the area of ​​a dysfunctional or threatened smallpox farm.

The meat of the killed poultry is used after a veterinary and sanitary examination in accordance with the rules of veterinary sanitary examination. Carcasses of emaciated poultry, as well as those with lesions in different areas, are disposed of. If smallpox lesions are found only on the scalp, it is disposed of, and the carcass and unaffected organs are disinfected by boiling. Corpses, blood and all post-mortem waste are disposed of. Down and feathers are disinfected and taken to processing plants in containers with double packaging and a special label "To be disinfected!" with an indication in the veterinary certificate of the trouble of the farm for smallpox. Down and feathers are disinfected with flowing steam, formaldehyde vapor, or by immersing them for 1 hour in an alkaline formaldehyde solution (A.A.Zakomyrdin, 1966).

It is forbidden to take out birds of all ages and species from the farm, with the exception of birds intended for slaughter at poultry processing enterprises, with strict observance of the necessary precautions. Eggs from safe poultry houses can be used for incubation only within the same farm. Day-old chicks, turkey poults and chicks of other species of birds should be removed from the incubation workshop, provided they are reliably isolated from poultry farms that are unfavorable for smallpox and other measures are taken to prevent the spread of smallpox infection. Selling chickens to the public is prohibited. Containers used to transport carcasses and eggs are disinfected after each use. It is recommended to disinfect soft containers (sackcloth, tarpaulin, matting, ropes, etc.) with flowing steam, but you can also disinfect it by soaking in disinfectant solutions or boiling in water with the addition of 1-2% soda, as well as process it in chambers using steam-air or steam-formalin methods. It is better to disinfect solid containers (cages, boxes, cushioning material, etc.) by immersion for 0.5-2 hours in baths with disinfecting solutions. It is prohibited to take out feed, droppings, equipment and inventory.

On a farm that is not doing well for smallpox, mechanical cleaning, disinfection and pest control are regularly carried out. As disinfectants, use a 3% hot solution of sodium hydroxide (exposure 3 hours), a clarified solution of bleach containing 2% active chlorine (exposure 4 hours), 2% formaldehyde solution (3 hours), 20% suspension of freshly slaked lime by whitewashing twice with an interval of 1 hour. It is recommended to spend 1 liter of the preparation per 1 m2 of the surface to be disinfected. Sealed rooms are disinfected with aerosols of a concentrated formaldehyde solution or formalin-creolinic mixture in a ratio of 3: 1, spending 20 ml of the preparation per 1 m3 of the room (exposure for 1 day). The houses must be clean and dry. Crowded poultry should not be allowed. Manure and garbage are subject to mandatory biothermal disinfection in accordance with the rules of the current guidelines. The quarantine is removed from the farm no earlier than two months after the elimination of the disease and the final disinfection. In farms that were previously unfavorable for smallpox, depending on the epizootic situation, for several years after the elimination of the disease, for a preventive purpose, a total immunization of birds is carried out in accordance with the current guidelines for the use of dry embryo-virus from pigeon virus against smallpox. Preventive vaccination of poultry is also carried out in farms threatened by smallpox, including all poultry owned by individual owners.

Smallpox of chickens can have the following symptoms, depending on the form of the disease:

• The cutaneous form (or smallpox) is the most common form. In this case, in domestic chickens, on those parts of the body where the feather cover is absent (catkins, crest, area around the eyes and at the base of the beak), growths similar to warts begin to appear. The growths are covered with blood scabs. The cutaneous form of smallpox disappears after 5-6 weeks. At the same time, the death of adult chickens is small - about 6-8% of the total livestock.
• Diphtheria form - with this form, the oral cavity, esophagus, larynx and trachea are affected. In these places, sores or lesions of a yellowish color are formed. Formations interfere with breathing, chickens begin to wheeze and cough. The characteristic signs of the diphtheria form are the stretching of the neck, a constantly open beak, and heavy breathing with a whistle. The bird may refuse feed due to the fact that it is difficult for it to feed. If smallpox formations spread to the nasal mucosa, then rhinitis begins in chickens with yellowish discharge. Due to the defeat of the nasopharynx, pathological changes in the lacrimal canal can be noticed - dense swellings filled with pus appear around the eyes. With the diphtheria form, chickens often develop diphtheria inflammation, which is characterized by swelling of the eyelids, increased tearing, fear of light and purulent-mucous discharge from the eyes, which form crusts on the eyelids. In severe cases, the eyes can be completely destroyed due to corneal perforation. The mortality rate in the diphtheria form is about 50%.
• Mixed form - this form is characterized by symptoms of both the cutaneous form of smallpox and the diphtheria form. Changes are found both on the skin and on the mucous membrane of the bird's mouth. The mortality rate of livestock in a mixed form is about 30-50%.