Inclusion body hepatitis (IBH) is an acute
disease of young chickens associated with anemia and hemorrhagic
disorders. A similar disease has been reported in quail with quail
bronchitis ( Quail Bronchitis: Introduction) caused by an avian
adenovirus. Once considered common, IBH is now rarely diagnosed, but it
has been seen in many areas of the world.
Etiology, Transmission, and Pathogenesis:
Adenoviruses have been considered to be
the cause. A birnavirus (the cause of infectious bursal disease
[IBD], Infectious Bursal Disease: Introduction ) and a
circovirus (the chick anemia virus [CAV], Chicken Anemia Virus Infection: Introduction )
have been associated wit. adenovirus infections; both of these cause
immunosuppression and contribute greatly to the severity of disease
caused by adenoviruses.
Adenoviruses are ubiquitous and are
transmitted horizontally and vertically. Infections are common and
widespread in chickens. Chicks and young chickens are affected most
commonly. Infection by adenovirus usually results in minimal hepatic
disease; however, if birds infected with the IBD virus or CAV are
infected with adenoviruses, clinical disease becomes evident.
Clinical Findings, Lesions:
Sudden mortality usually is seen in
chickens <6 wk old. Mortality is seldom >7%. Signs associated
with diseases caused by other pathogens (eg, bacteria, fungi, or
viruses) commonly occur if birds are immunosuppressed. In these
cases, mortality rates may be >30%. Hemorrhage may occur in any
organ. The bursa of Fabricius usually is small. Bone marrow, livers,
and other organs usually are pale. Congestion and multifocal areas
of light or dark discoloration are seen in. livers. Microscopically,
solitary prominent basophilic inclusion bodies are seen in
A tentative diagnosis is based on
typical microscopical findings and confirmed by isolating
adenoviruses from portions of liver. Immunosuppression resulting
from infection with the IBD virus or CAV usually is the.
predisposing event that culminates in clinical IBH.
Treatment, Control, and Prevention:
Treatment consists of nursing care.
Antibiotics may help prevent secondary bacterial infections.
Sulfonamides are contraindicated if evidence of hematologic disease
or immunosuppression is seen.
Broiler-breeder flocks should have high
levels of IBD antibody before they begin to lay fertile eggs.
Vaccines against IBH or CAV are not commercially available in the
USA. In Australia, a peracute form of IBH has occurred in broiler
chickens in the absence of infections with either the IBD virus or
CAV. A live IBH vaccine is effective in preventing IBH in progeny
when administered P. or in drinking water to breeder chickens
several weeks before the onset of lay. In Pakistan, IBH is an
essential part of the hydropericardium syndrome of broiler chickens
in which an excessive amount of clear, watery or jelly-like fluid
accumulates in the pericardial sac of chickens 3-6 wk old. A
formalized vaccine prepared from the homogenated livers of
experimentally infected chickens is 80-90% effective in preventing
the hydropericardium syndrome when administered SC to chicks 10-12