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synonyms IBD:Gumboro Disease


Type 1 avibirnavirus strains

Type 1: Both classic and highly pathogenic (vvIBD) serotypes are recognized. Pathogenic Delaware variants A through E predominate in the USA and Central America. The vvIBD strains occur frequently in the Middle East, Asia and Africa.

Type 2: Turkey strains are apathogenic to chickens.

 Occurrence and Economic Significance

The disease affects immature chickens world wide. Acute infection with classic mild or variant strains results in up to 5% mortality. The variants are more immunosuppressive than the classic strains. Very virulent (vvIBD) virus may kill up to 50% of susceptible flocks.

Avibirnaviruses are immunosuppressive and predispose flocks to intercurrent viral pathogens and secondary bacterial infection.

Infectious Bursal Disease is a major restraint to productivity and profitability in the poultry industries of both industrialized and developing nations.



Direct contact of young birds with infected flocks in multi-age units results in persistent “rolling” infection which is difficult to control. Indirect infection with IBDV occurs within days of placing chicks as the agent can survive in a contaminated environment for up to 3 months.

Contaminated equipment, non-pelleted feed containing inadequately heat treated poultry by-product meal, housing, and clothing of personnel are frequently sources of infection.

 Clinical Signs

Flocks are affected acutely and show variable morbidity (5-50%) and rapidly ascending mortality (5-50%), depending upon the pathogenicity of the IBDV strain and the susceptibility of the flock. Affected birds are depressed and show recumbency, ruffled plumage and white diarrhea. There are no characteristic signs specific to IBD.


Dehydration and muscular hemorrhages are evident in dead birds. In acute cases the characteristic lesion comprises enlargement of the bursa of Fabricius which is often surrounded by gelatinous exudate. Sectioning the organ may show hemorrhages. Recovered birds show bursal atrophy.

Airsacculitis and E. coli septicemia are frequent complications following exposure to respiratory viruses especially with superimposed climatic or environmental stress.


Acute bursal changes are generally diagnostic. Histological examination of bursas from broilers or pullets at various stages of the disease will show edema progressing to atrophy. IBDV can be isolated in specific pathogen free embryonated eggs or on tissue culture. Serotyping carried out in reference laboratories using monoclonal antibodies, can identify specific IBDV isolates.

Antibody response in vaccinated flocks should be routinely monitored using ELISA serology.


Parent flocks should be immunized with one or more attenuated live (mild or intermediate) vaccines followed by an oil-emulsion booster. This program will promote transfer of high and uniform levels of antibodies to progeny. Broiler and replacement layer chicks should be vaccinated with live-attenuated vaccine which primes the immune system. In North America a mild live multivalent (classic and variant) vaccine is administered by the in ovo route to provide initial stimulation of the immune system. This is required if chicks are exposed to IBDV at the time of placement. In areas of the world where relatively avirulent strains of IBD virus occur, mild strain vaccines may be administered from day old to 14 days. Subsequent administration of intermediate strain vaccine may be necessary depending on factors including:

  • Risk of infection.
  • Strains of virus prevalent in the area of operation.
  • Intercurrent exposure to respiratory viral infections.

A combination of live IBD virus with corresponding antibody is available to be administered either in ovo or at day-old by the subcutaneous route. This vaccine is effective in the presence of high levels of maternal antibody.

The age of administration of live attenuated vaccines depends on the level of maternal antibody and the risk of infection. In areas of the world where the very virulent (vvIBD) strain occurs, intermediate-plus (“hot”) vaccines are administered in drinking water. Selection of the age of vaccination is determined by applying the following formula based on the results of ELISA serology at day old. This formula relates the initial antibody level to the rate of decline in maternal antibody to obtain the optimal age for vaccination.

Age of vaccination: where 22.36 is the square root of 500 ELISA units, (the threshold of protection) and 2.82 is the mean half life (in days) of maternal antibody.

It is necessary to maintain strict levels of biosecurity and to operate flocks on an all-in-all-out basis in areas where severe infectious bursal disease is endemic.

Fowl Cholera

Fowl cholera is a contagious, bacterial disease that affects domestic and wild birds worldwide. It usually occurs as a septicemia of sudden onset with high morbidity and mortality, but chronic and asymptomatic infections also occur.

Newcastle Disease

Newcastle disease is an infection of domestic poultry and other bird species with virulent Newcastle disease virus (NDV). It is a worldwide problem that presents primarily as an acute respiratory disease, but depression, nervous manifestations, or diarrhea may be the predominant clinical form. Severity depends on the virulence of the infecting virus and host susceptibility. Occurrence of the disease is reportable and may result in trade restrictions.

IBD is the reason for great economic loss of poultry in bangladessh

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Poultry Diseases

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