Gumboro disease: monitoring the quality of vaccination using ELISA. Vaccines against infectious bronchitis of chickens and gumboro disease in Russia

G.V. Beginin, chief veterinarian PF "Gayskaya"

The epizootic and economic well-being of poultry enterprises largely depends on timely diagnosis and measures specific prevention against infectious diseases, which include Gumboro disease.

Gumboro disease at the Gayskaya poultry farm in the Orenburg region was first registered in November 1995 among 45-day-old chickens of the Zarya-17 cross. Clinically, the chickens were observed to be lethargic, lack of appetite and watery diarrhea. Characterized by ruffled plumage and at times muscle tremors.

During the epizootic period, the disease manifested itself in 6 workshops of the poultry farm. The disease was observed simultaneously in different poultry houses and the number of sick chickens in some poultry houses reached 50%, and in others – 10–20%. Chicken mortality in some workshops was more than 30% within 7–10 days. The maximum death of birds was noted on the 3rd–5th day of illness and decreased in the next 4–5 days.

At autopsy, dryness was noted subcutaneous tissue, pinpoint or diffuse hemorrhages in the pectoral and femoral muscles, the bursa of Fabrice was enlarged 2–3 times, hyperemic or with hemorrhages (in 30–40% of cases), sometimes there were fibrin deposits in its cavity. Kidney lesions were noted in 40% of the examined corpses.

They were enlarged, with hemorrhages, and there was an accumulation of urates in the ureters. The diagnosis was made on the basis of epizootic data, clinical signs, pathological changes and the results of laboratory tests conducted at VNIVIP.

Since the outbreak of Gumboro disease, different vaccines have been tested at the poultry farm, varying in their effectiveness due to the presence of maternal antibodies and changes in poultry crosses.

Initially, against the background of low passive immunity, the double use of the vaccine from the “VNIVIP” strain made it possible to ensure high safety and productivity of poultry in unfavorable conditions. After a long period of successful prevention, clinical signs and lesions in the bursa of Fabricius during autopsy of dead birds appeared in the vaccinated flock after reaching 35–37 days. Then the disease spread to other buildings where birds of an age susceptible to the IBD virus were kept.

An analysis of the reasons for the failure of vaccine prophylaxis showed that by that time the young animals accepted for rearing had high levels of maternal immunity, since they were obtained from hyperimmunized laying hens, and in the batch of chickens where a specific death was observed, there were violations of the vaccine application technique, in some In some cases, the poultry house housed chickens of different ages with different immune backgrounds.

It was possible to stabilize the epizootic situation on the farm with the help of a vaccine from the BG strain. With the transition to new vaccine clinical manifestation diseases were not observed, but they encountered such problems as atrophy of the bursae of Fabricius, retardation of poultry in growth and development, a high percentage of their rejection, a low percentage of commercial pullets and kidney pathology in replacement young stock caused by an increased content of uric acid salts in the ureters.

After changing the poultry population to the Rhodonit cross, in which the parent flock was not vaccinated with the inactivated Gumboro vaccine and the level of maternal antibodies in the RDP of day-old young animals did not exceed 30%, they began to use a vaccine from the KBK strain produced by Biovet LLC (St. Petersburg ). The vaccine was administered once into the upper third of the neck of day-old chickens subcutaneously in a volume of 0.2 ml. To dilute the vaccine, we used Marek's disease vaccine diluent produced by the Kursk biofactory.

The effectiveness of the vaccine from the KBK strain was assessed by the level specific antibodies in the RDP, bursal index and titers to the Newcastle disease virus.

In the blood serum of vaccinated chickens 25–30 days of age positive reaction in RDP was noted in 80–100% of cases. The bursal index at the age of 30 and 40 days was at least 3.5. The bag had a natural color and without visible signs defeats. Group immunity against Newcastle disease 15 days after revaccination was 6.42 log2, which indicates a pronounced immunological reaction of the bird to the vaccine. Observations have shown that the vaccine from the KBK strain does not cause immunosuppression; the growth and development of poultry complied with zootechnical standards. Safety among young animals during the period of use of this vaccine increased by 5%, the yield of commercial pullets was 97% with high uniformity of the herd.

Some batches of chickens were vaccinated against Marek's disease and Gumboro disease simultaneously. Performance indicators for separate and joint immunization against Marek's and Gumboro's diseases did not differ significantly.

In 1998, another change of livestock was carried out to the “Loman White” cross, where the prevention of Gumboro disease was carried out according to the program of the “Loman” company (Germany) and passive immunity in the first days of life, according to ELISA data, was 1: 5000 and higher. In this situation, we had to change the vaccine and adjust existing program disease prevention.

Taking into account previous experience in disease prevention and positive reviews colleagues on the prevention of Gumboro disease using an inactivated vaccine on young birds, it was decided to vaccinate with this vaccine from the “52/70 M” strain (produced by Biovet LLC). At the same time, a comparison was made with a live vaccine from the BG strain and a scheme for using the killed vaccine was worked out to develop tactics for preventing the disease in the future.

To do this, one group of chickens was vaccinated with an inactivated vaccine at 10 days according to the instructions for using the drug; the second group was vaccinated at 16 days with an inactivated vaccine; the third and fourth groups of chickens were simultaneously vaccinated with inactivated and vaccine from the “KBK” strain at 10 and 16 days, respectively; chickens of the fifth group were vaccinated with a vaccine from the “BG” strain at 7 and 17 days.

The effectiveness of vaccines and their application schemes was judged by the well-being of the farm against Gumboro disease, general safety, productivity, business output of replacement young stock and by the results of blood serum studies for the presence of specific antibodies in the RDP of 30-, 40-, 50- and 60-day-old chickens. At the same time, we studied the level of post-vaccination immunity against Newcastle disease, and also determined the bursal index in different terms poultry rearing.

Comparative production indicators for raising poultry according to the specified vaccination schemes are given in Table No. 1.

Table 1
Performance indicators of chickens vaccinated with different vaccines against IBD

Indicators	Group numbers
Number of goals
Average daily weight gain, g
weight 1 head. when transferred to 112 days, g
% business pullet
Safety, %
Uniformity, %
% of egg laying in 150 days.
Culling, %

From the presented data it is clear that the vaccines used against Gumboro disease according to the indicated schemes provide complete protection of chickens from the field virus. Administration of inactivated vaccine to chickens does not cause adverse reactions local and general. Chickens vaccinated with an inactivated vaccine at different times separately and in association with a live vaccine have the highest rates of safety (up to 99.4%), average daily weight gain that meet regulatory requirements, a high percentage of commercial pullet yield (97.4%), and a low percentage of rejection (0.49%) and high uniformity of the herd (88.3%).

The dynamics of serological indicators of the reaction to the introduction of vaccines indicates that the most active group immunity was established in group IV of chickens simultaneously vaccinated live and inactivated by vaccines at 16 days. The arithmetic mean titer of serum in the RDP was 3.8 log2. High bursal index values ​​(more than 5.2) were noted in groups I-IV, while in group V, low bursal index values ​​were observed starting from 30 days of age.

CONCLUSION
The effectiveness of preventing Gumboro disease is closely related to the type of vaccine, compliance with the rules for its use, and the presence of maternal antibodies, which negatively affect the development of post-vaccination immunity, both when administered live and inactivated vaccines.

The vaccine from the KBK strain is effective against a low immune background of passive antibodies. The use of a vaccine from the “BG” strain helps to stop the infection, but causes damage to the bursa and kidneys, which leads to a decrease in the overall safety and productivity of the bird.

High safety and productivity in our farm conditions was achieved with joint vaccination with inactivated and live vaccines against IBD at 16–18 days.

Prepared based on the materials of the “Vth International Veterinary Congress on Poultry Farming” for the website

Infectious bursal disease, or Gumboro disease, is a common disease in chickens under four months of age. Manifests itself in the form of diarrhea, damage to the cloacal bursa, kidneys, gastrointestinal tract, intramuscular hemorrhages.

What is Gumboro disease in chickens, how to diagnose it and how to protect yourself from it– we invite you to talk in this article.

Gumboro disease: affects chickens and turkeys

Pathogen bursal disease is a virus of the Birnoviridae family that infects lymphoid cells, causing a sharp decrease in the bird’s immunity. The virus targets immature β-lymphocytes containing immunoglobulin M. There are two serotypes, roughly speaking, types, of this virus: 1 - affects only chickens, 2 - only turkeys. Moreover, the chicken Gumboro virus exists in several variations (subtypes).

Gumboro disease: how to get infected

Gumboro disease is highly contagious: up to 100% of birds of one group can get sick, and 40-60% die.

Methods of transmission of the pathogen Gumboro disease:

Infected birds; sparrows, pigeons, etc. can be carriers of the virus.

Feed, in particular – feed pests

At the same time, in a closed room, the avian bursal disease virus can live for up to three months, and in dirty rooms - in dust, uncleaned cages, and equipment - it can be stored for years. Not afraid sunlight, shows durability outside the room. In dry droppings it remains active for about two months, on the surface of glass and walls - about one month.

Gumboro disease: how it manifests itself

Externally, the chicken bursal disease virus appears already on the third day after entering the bird’s body. Overall feature acute form The course of Gumboro disease (subacute course also occurs) is an unexpected, high incidence of poultry (40-100%), an acute peak in mortality (20-40%) and a rapid recovery within 4-7 days.

At the same time, the Gumboro virus most often occurs at the age of 6-8 weeks, and at 3-4 weeks.

It all starts with diarrhea, the droppings become watery, yellow-white. The chickens look depressed, huddled together, their feathers are ruffled, and their vents are dirty. The bird does not eat or drink. In this form, the disease manifests itself within 5-7 days, after which Gumboro disease is often complicated by manifestations of colibacillosis.

When the bird is opened, a cherry-colored cloacal bursa enlarged by 2-3 times is observed. Often blood clots may be visible in the cavity. There are hemorrhages under the skin on the chest, wings, thighs and in the glandular stomach.

Changes are observed in the bursa of Fabricius already on the third day: due to swelling and accumulation of secretions, it increases in size and becomes gray-yellow. On the fourth day of the disease, its weight almost doubles, hemorrhages, turbid contents and necrotic deposits are found in it. Sometimes intense hemorrhages are recorded, covering the entire bursa. On days 7-9, atrophy and fibrosis of the bursa are observed.

However, to finally put diagnosis of Gumboro disease in chickens is possible only on the basis of laboratory results.

Gumboro disease in chickens: prevention, vaccination, measures in case of a disease outbreak

In addition to compliance hygiene rules poultry owners, chicken owners are obliged to regularly fight against virus carriers - chicken feather eaters, and monitor the quality of feed.

Chickens are vaccinated with Gumboro chicken virus vaccines in the event of a threat of disease outbreak. The following vaccines are used on the territory of Ukraine:

Inactivated vaccine from the BER-93 strain

Virus vaccines from strains UM-93 and VG-93

Gallivac IBD (France)

Inactivated vaccines N.D.V.+I.B.D+I.B. and quadractin N.D.V.+I.B.D+I.B.+Reo and NECTIVE FORTE (Israel).

There is no cure for Gumboro disease!

At diagnosing Gumboro disease in chickens a farm in which a disease is discovered is declared unfavorable and restrictions are introduced in accordance with the Instructions. Two months after removal, the birds are removed from the dysfunctional farm. Carry out complete disinfection of the farm. Farms in which IBD has not been observed for one year are considered free from chicken bursal disease.

Tatyana Kuzmenko, member of the editorial board, correspondent of the online publication "AtmAgro. Agro-industrial Bulletin"

Mass breeding of chickens on farms requires compliance with many rules and regulations. Highly productive and healthy birds are the result of daily care for their health, because today there are many diseases with a rapid pace of development and a high mortality rate. One of them is Gumboro disease: let’s look at its features and the main methods of control.

What kind of disease is this

Gumboro disease, or infectious bursitis, - spicy viral disease chickens, the first appearance of which became known in 1962 in the city of Gumboro (United States of America). Today it affects livestock not only in America, but also in other countries of Europe and Asia.

Economic damage

For poultry farmers, the losses are significant and are calculated not only in the number of dead livestock, but this is 10–20% of the total flock. Sometimes deaths are observed in 50% of the total number of sick chickens: it all depends on the age, breed and conditions of their keeping.

A large percentage of culled carcasses, which lose their attractiveness due to multiple hemorrhages and exhaustion, also bring losses.

The disease also has many indirect negative factors. Firstly, it greatly weakens the herd, making it susceptible to many other infections, and secondly, it significantly reduces the effect preventive vaccinations, thirdly, it negatively affects the productivity of the livestock.

Important!There is still no way to cure infectious bursitis. Most effective method combating the disease - timely vaccination.

The causative agent of the disease

The causative agent of the disease enters the bird's body through the mucous membranes. It is able to withstand temperatures up to +70°C for half an hour, and is resistant to alkalis (pH from 2 to 12) and acids, as well as lipid solvents. The causative agent of Gumboro disease can survive in chicken droppings for up to four months.

Only disinfectants can quickly destroy virus cells:

• formalin;
• iodine derivatives;
• chloramine

This virus does not have antigens and is classified as a reovirus. For a long time Bursitis virus was classified as an adenovirus. For some time after the disease was identified, it was believed that infectious bursitis and infectious bronchitis were caused by the same pathogen.

Only chickens are susceptible to the infectious bursitis virus, although it is believed that the disease also affects sparrows and quails.

Epizootological data

The main risk group is reproductive farms that house individuals of different ages. The main source of bursitis is chickens infected with the virus. Most often, the disease has an acute and subacute course; less often, bursitis passes without symptoms.
The virus quickly affects the entire herd. It is noteworthy that Gumboro disease is not observed in young birds up to two weeks of age and in adult birds. Even if they are artificially infected, they will remain immune to the virus. Chicks suffer from bursitis between the ages of 2 and 15 weeks. Chickens aged 3 to 5 weeks are most susceptible to it.

Did you know? - chickenoriginally from South America,who carries blue and green eggs. The reason for this phenomenon is increased content in the chicken's body there is a special bile pigment that colors the shell.

Shared housing of patients and healthy birds, contaminated food and water, droppings, bedding - these are all factors in the spread of the virus. It can also be transmitted mechanically - it is carried by people, other species of birds, and insects.

Clinical signs

Gumboro disease has a hyperacute course. The chicken dies within a week, sometimes even faster. Incubation period bursitis lasts from three to fourteen days.

Clinical manifestations are similar to coccidiosis:

• diarrhea;
• severe apathy;
• trembling;
• disheveled;
• refusal of food;

A postmortem examination of a bird infected with the bursitis virus allows us to identify characteristic features indicating the cause of death - inflammation and hyperplasia of the bursa of Fabricius, profuse hemorrhages in muscle tissue, skin and jade.
Such signs allow a clear diagnosis.

Important! Chickens that die from Gumboro disease die in a characteristic position - with their legs and neck outstretched.

Pathogenesis

The disease is characterized by rapid spread: its pathogen, which enters the body orally, reaches lymphoid cells intestines. Rapid dissemination of the disease is achieved by the penetration of these cells into all circulating systems.

After 11 hours, the virus infects the bursa of the plant. Thus, after two days, infectious bursitis affects all organs. The main place of concentration of the virus is the bursa of Fabricius: it can remain there for up to two weeks.

Defeat lymphoid tissue leads to a pronounced immunosuppressive effect. The number of lymphocytes sharply decreases, and almost complete suppression of immunity is observed.
In general, immunity weakened by the Gumboro disease virus leads to increased morbidity in poultry viral hepatitis, salmonellosis, gangrenous dermatitis and coccidiosis.

Diagnostics

Clinical and pathological features allow accurate diagnosis typical shape diseases. Identify an atypical course of the disease or establish it early stages allows laboratory test, based on the isolation and identification of the virus.

To rule out bursitis when differential diagnosis, you need to make sure that the chickens are not sick:

• lymphoid leukemia;
• sulfonamide poisoning;
• fat toxicosis.

Treatment

Due to the fact that the body of recovered chickens develops immunity to Gumboro disease, a large number of live vaccines have been created with high degree immunogenicity. The most common vaccines: Gumbo-Vax (Italy), LZD-228 (France), Nobilis (Holland).

Did you know?A chicken can be put into a state of hypnosis by gently pressing its head to the ground and drawing a straight line from the bird's beak with chalk.

Day-old chicks are vaccinated by drinking or intraocularly, young animals over three months of age are vaccinated intramuscularly. Antibodies from vaccinated individuals at high levels are transferred to chickens and protect them during the first month of life.

Prevention

To avoid the disease, you must:

• provide the bird with a nutritious diet;
• carry out cleaning and disinfection in a timely manner;
• keep birds of different ages separately;
• equip the poultry house with individuals of the same age;
• incubate eggs separately own production and imported;
• place day-old young stock brought from other farms separately from the main herd;
• comply with the timing of preventive vaccination;
• ensure the protection of the herd from the introduction of infection: purchase eggs and day-old young animals only from farms that are free from infectious bursitis;
• strictly comply with zootechnical and veterinary requirements for keeping and feeding birds.

Compliance preventive measures and careful attention to the products and young stock purchased for incubation can significantly reduce the risk of birds becoming infected with infectious bursitis. In the event that this does happen, the sick individuals must be destroyed.

Infectious bursitis (Gumboro disease) is an acute contagious viral disease chickens, characterized by apathy, diarrhea, anorexia, damage to the bursa of Fabricius, extensive intramuscular hemorrhages and kidney damage.

Historical reference. For the first time, infectious chicken bursitis was described by researchers in 1962 in the city of Gumboro, USA. Today, the disease is diagnosed in many countries around the world - the USA, Canada, Mexico, England, Germany, France and other European countries, India, Japan, Israel, and South African countries.

Economic damage quite significant and is determined by losses from death of up to 10-20% of the poultry population, a large percentage of carcasses being rejected due to subcutaneous, intramuscular hemorrhages and exhaustion.

The causative agent of the disease belongs to reoviruses. The size of virions is 50-70nµ. They have icosahedral symmetry. The capsid consists of a single layer with 92 capsomeres. The virus is cultivated in chicken embryos of 9-11 days of age, causing their death 4-6 days after infection in the allantoic cavity at KhAO and in yolk sac, as well as a culture of kidney cells and chicken embryo fibroblasts. The virus is relatively resistant to factors external environment. Indoors, on metal and wooden surfaces, the virus remains active for 122 days. The virus is viable in water, food and droppings for 52 days. The virus retains its infectivity when heated to 60°C for 90 minutes, at 56°C for 5 hours. Only at a temperature of 70°C the virus is destroyed in 30 minutes. The virus is resistant to chloroform, ether, trypsin, while 5% formalin kills it. Chloramine and sodium hydroxide solutions have an inactivating effect.

Epizootological data. IN natural conditions 2-15 week old chickens are susceptible to the virus, 2-4 week old chickens are especially sensitive. There are reports of quail sensitivity to the virus. The disease is observed at any time of the year in different climatic zones, regardless of the breed of chickens. The disease is especially widespread in reproductive farms where poultry is present. of different ages. The source of the virus is a sick or recovered bird, a virus carrier, which sheds it in its droppings for up to 14 days. The virus is spreading rapidly in poultry flocks. It is transmitted when sick and healthy chickens are kept together, through contaminated feed, water, bedding, droppings, and it is also possible to transmit the virus mechanically - by service personnel, through care items contaminated with the virus, with slaughter products, other species of birds, insects, especially yellowwings. Ducks, turkeys, geese, guinea fowl, and quail can be carriers of the virus.

The pathogen enters the body through the mucous membranes of the nasal cavity, oral cavity, conjunctiva in vivo. The bird becomes infected through nutrition.

Pathogenesis. The causative agent of infectious bursitis that has entered the body of a bird orally can be detected in intestinal lymphoid cells within 4-5 hours. From lymphoid cells with the blood and lymph flow, bypassing the Kupffer cells of the liver, the virus enters all organs and tissues. After 11 hours, the virus begins to multiply in the bursa of Fabricius. In this case, the phenomena of viremia in the bird’s body are short-lived, lasting up to two days. Subsequently, we detect the virus in all parenchymal and lymphoid organs, but most in high concentrations in the bursa of Fabricius, where it persists for up to 2 weeks.

Damage to the lymphoid tissue of a sick bird is accompanied by a pronounced immunosuppressive effect, manifested in a significant decrease in the number of lymphocytes in the bird’s blood, up to the suppression of all. In dependent functions of immunity, especially the primary humoral one responsible for the formation of antibodies. There is a decrease in the level of serum complement and blood clotting, with the possible involvement of immune complexes in the development of the disease. All this leads to a loss of effectiveness of immunization of the affected bird against, and Marek. Susceptibility to increases by 3-6 times. Wherein enough level protection against Newcastle disease can only be achieved by immunizing one-day-old chicks or 2-3 weeks before infection with infectious bursitis virus. Against such an immunosuppressive background, in the absence of lymphocytes in the blood, the poultry often worsens or re-emerges. various infections something like gangrenous dermatitis.

Clinical signs . The incubation period is 2-6 days. The disease begins super-acutely, symptoms of the disease in birds appear suddenly, from 10 to 20% of chickens fall ill with a mortality rate of 0.5-15%.
In sick chickens we note depression, disheveled behavior, refusal to feed, trembling, unsure gait, symptoms of diarrhea ( watery diarrhea with whitish-yellow feces), soiled feathers around the cloaca. Some chickens appear severe itching around the cloaca, which they try to calm down by pecking at this area. This is often the first sign of an onset of illness for service personnel; the patients drink a lot, their feathers are ruffled.

At acute course disease, the death of chickens is observed, which reaches its maximum on the 3-4th day of illness (3-80%). The mortality curve is very characteristic and must be taken into account when making a diagnosis. The duration of the disease in birds in the affected group is 4-8 days.
In the subacute course, the symptoms of the disease are less pronounced and the death rate is insignificant.

In poultry farms, where the disease is not registered for the first time, it can be asymptomatic. In such farms, chickens do not show signs of illness, and when examining blood serum, virus-neutralizing and precipitating antibodies are detected.

Pathological changes. In chickens, we note anemia and dehydration of muscle tissue; in the muscles of the leg, thigh, wings and chest we often find pinpoint and striped hemorrhages. We also find hemorrhages on the mucous membrane of the glandular stomach. The kidneys are enlarged, light gray in color (from the accumulation of salts in the tubules uric acid). The liver and spleen are hypertrophied. In some birds, the ureters may also be congested with urate. We note signs of catarrhal enteritis, serous pericarditis, and peritonitis. At the same time, the most characteristic changes for this disease are found in the bursa of Fabricius. In the first 2-4 days after the bird is infected, it increases 2-3 times. Its mucous membrane is swollen, hyperemic, with hemorrhages and necrotic areas, sometimes in its lumen we find fibrin clots, and later a cheesy mass. At asymptomatic these changes are less pronounced and can only appear in the form mild hyperemia or completely absent.

From the 10-12th day after infection, signs of atrophy of the bursa of Fabricius, thinning of the folds of the mucous membrane, which are often hyperemic and have pinpoint hemorrhages, are observed.
The leading cytomorphological sign is necrosis of cells of the lymphoid tissue of the bursa of Fabricius. In place of the destroyed follicles, proliferation of corticomedullary epithelium is established, fermenting mucous glands. We observe a general picture of purulent and necrotic inflammation with vacuolization in the bursa of Fabricius.

Diagnosis and differential diagnosis are based on the analysis of epizootic, clinical data, pathological changes and the results of laboratory (serological and virological) studies, including isolation and identification of the virus. A study is carried out on the bursa of Fabricius, spleen, liver, and kidneys taken from dead or forcibly killed birds. All this is delivered to the veterinary laboratory in a thermos with ice. For serological testing, 20-25 blood serum samples are sent, from daily and over 60 days of age, obtained at the onset of the disease and after 21 days. The veterinary laboratory uses the following research methods: isolation of the virus in chicken embryos or in cell culture; bioassay on susceptible chickens; identification of the isolated virus in neutralization reactions (RN) and diffuse precipitation in agar gel (DPR); determination of specific antibodies in blood serum in RN and DNP; detection of histological changes in organs and tissues Research is carried out only on SPF embryos and SPF birds.

Infectious bursitis must be differentiated from the following diseases:

• , which clinically manifests itself in approximately the same way as infectious bursitis, we make an exception by conducting a scatological examination;
• in which hemorrhagic lesions characteristic of respiratory symptoms, occurs with high contagiousness and lethality, birds of all ages are susceptible;
• fatty liver and kidney syndrome, which is accompanied by hemorrhages and kidney damage, very rarely ends in death, chicken carcasses have a pale pink color;
• nephrosonephritis, which is caused by the infectious bronchitis virus, is similar in damage to parenchymal organs, but is manifested by respiratory disorders and does not affect the bursa of Fabricius;
• hemorrhagic syndrome of a toxic nature - occurs when poisoned by sulfonamides or mycotoxins, observed in birds of all ages, hemorrhages are concentrated in the visceral organs;
• — atrophy of the bursa of Fabricius is observed, the lesions are limited to the epithelium.

The disease additionally needs to be differentiated from lymphoid leukemia and.

Immunity and means of specific prevention. The recovered bird develops immunity, which is used for diagnostic test and vaccine development.

Numerous live vaccines that are highly immunogenic have been developed and used abroad. In Italy - gumbo-vax, LZD-228 (Merrier, France), Nobilis (Holland). These vaccines are harmless, do not have an immunosuppressive effect, are effective, stable during storage and transportation, and are convenient for use.
Chickens are vaccinated intraocularly or by drinking the vaccine at one day of age, as well as intramuscularly in groups older than 12 weeks. Vaccines can be used for complex vaccinations in combination with vaccines against diseases and infectious bronchitis. Inactivated emulsified vaccines are also used. Vaccination of chickens ensures the safety and usefulness of lymphoid tissue. High titres of maternal antibodies are transferred with the egg and protect the offspring during the first four weeks.

Disease prevention measures. To prevent Gambora disease, poultry farm owners must comply with the following requirements:

• strictly observe measures to protect the farm from the introduction of infection, and also supply bird flocks with hatching eggs and day-old young animals only from farms free from Gumboro disease;
• carry out preventive vaccination of young animals in all categories of farms with live vaccines from an intermediate strain, and vaccinate replacement young animals of the parent and breeding herds with an inactivated vaccine;
• create for the bird optimal conditions maintenance and provide them with nutritious feed;
• place different birds age groups in geographically isolated areas;
• equip poultry houses with birds of the same age;
• observe inter-cycle preventive breaks with thorough cleaning and disinfection of premises;
• disinfect imported breeding eggs, containers and transport used for their delivery;
• carry out separate incubation of breeding eggs imported to the farm and eggs received from one’s own parent flock;
• raise day-old chicks obtained from imported eggs separately from the rest of the poultry farm.

Each farm (farm) should ensure the necessary zoohygienic, veterinary and zootechnical requirements for keeping and feeding birds.

Measures to combat the disease.

When a diagnosis of infectious bursal disease (Gumboro disease) is made in accordance with the order of the Ministry Agriculture RF dated December 19, 2011 No. 476 “On approval of the list of contagious, including especially dangerous, animal diseases for which restrictive measures (quarantine) can be established.” By the Decree of the Governor of the region, restrictions are introduced on the farm and in accordance with” instructions for the prevention and elimination of infectious bird diseases bursal disease from October 25, 1995" on the farm prohibited:

• export hatching eggs. Day-old young animals, grown and adult birds, feed, equipment, inventory, etc. to other farms and sell to the public.

According to the restrictions allowed:

• sell eggs to the retail chain after disinfection;
• poultry should be slaughtered in the slaughterhouse (slaughterhouse) of the farm; in its absence, conditionally healthy birds should be sent for slaughter to the nearest meat processing plant only with special permission from the Chief State Veterinary Inspector of the region, in a separate batch within the time frame established by the State Veterinary Service and agreed upon with the poultry plant for immediate slaughter with compliance with current veterinary and sanitary rules and other veterinary regulatory documents preventing the spread of the pathogen.

Clinically healthy birds are immunized against IBD; in flocks with subclinical disease, vaccines from intermediate strains are used; in herds with acute and subacute course— vaccines from moderately pathogenic (“hot”) strains.

Along with vaccinations of young animals with live vaccines, immunization of breeding replacement young animals at the age of 100-130 days (one month before the start of egg laying) is carried out with an inactivated vaccine.

Vaccines are used in accordance with the instructions for their use.
Systematically culled. A weakened and sick bird. All poultry that have reached slaughter standards from premises in which the disease was recorded are killed for meat. Stop laying eggs for incubation, thoroughly clean and disinfect the hatchery, poultry houses, equipment, inventory, territory, transport, etc. Eggs are laid for incubation no earlier than 7 days after the departure of the last batch of incubated eggs.

Each poultry house is assigned maintenance personnel who are provided with special clothing, safety shoes, and disinfectants. At the end of the working day, workwear is disinfected with formaldehyde vapor.
In premises with sick birds, aerosol disinfection is carried out in accordance with current instructions on carrying out aerosol disinfection of poultry premises in the presence of birds.

The farm is improving the feeding and maintenance of birds, and introducing anti-stress additives (drugs) into the diet.

For wet disinfection of bird-free premises, use one of the following drugs: 2% formaldehyde solution, 4% sodium hydroxide solution, clarified bleach solution containing at least 3% active chlorine. Exposure for at least 6 hours. Consumption of disinfectants is 0.5 l per 1 m² of surface area to be treated; ceilings, walls, floors, wooden surfaces are whitened with 20% freshly slaked lime twice with an interval of 1 hour.

Litter and deep litter are transported to a manure storage facility for biothermal neutralization.

Restrictions on the farm are lifted after the delivery for slaughter of all poultry from poultry houses in which IBD disease was observed, completion of final veterinary and sanitary measures, and in the absence of the disease in more than three batches of young animals raised up to 90 days of age in all poultry houses of the farm during the professional break.

Infectious bursal disease (IBD, Gumboro) is an acute, highly contagious viral infection chickens, manifested by inflammation and subsequent atrophy of the bursa of Fabritsiev, various degrees nephroso-nephritis and immunosuppression. Clinically, the disease manifests itself only in chickens older than 3 weeks .

Feathers all around anus usually stuck together and colored White color because of large quantity urates.

Period highest mortality rate- age 3 - 6 weeks, but can be observed up to 16 weeks. Before the age of 3 weeks, IBD can be subclinical, but leads to suppression of the immune system.

In addition, diarrhea, anorexia, depression, and ruffled feathers, especially in the head and neck area, may occur.

Natural infection with IBD is mainly observed in chickens. In turkeys and ducks it can be subclinical, without immunosuppression. In premises where IBD was recorded once, the disease tends to recur, usually in a subclinical form. The corpses are dehydrated, often with hemorrhages in the chest, thigh and abdominal muscles.

The IBD virus belongs to the Birnaviridae family of RNA viruses. There are two serotypes of the virus, but only serotype 1 is pathogenic. The virus is very resistant to most disinfectants. In contaminated areas it can persist for months, and in water, feed and feces for several weeks. The incubation period is short, and the first symptoms appear within 2-3 days after infection. The lesions primarily affect the bursa of Fabricius; at the beginning, the bursa enlarges and becomes swollen. The IBD virus has a lymphocidal effect and primarily affects the lymphatic follicles of the bursa.

IBD lesions resolve various stages from isolated hemorrhages to severe hemorrhagic inflammation. The incidence is very high and can reach 100%, while the mortality rate is 20 - 30%. The disease progresses in 5-7 days and the peak mortality occurs in the middle of this period.

In some cases, the bag is filled with curdled fibrinous exudate, which usually takes the form of an impression of the shape of the folds of the mucous membrane. In birds that survived acute stage diseases, the bags gradually atrophy.

The kidneys suffer greatly from severe diathesis caused by urate deposition. The use of live vaccine in chickens is key point in the prevention of IBD. All poultry are vaccinated at the age of 10 days.

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