Infectious bursal disease (IBD) or
Gumboro disease is a highly contagious disease of young chickens caused by
infectious bursal disease virus characterized by immunosuppression and
mortality.
Young birds at around 2 to 8 weeks of
age that have highly active bursa of Fabricius are more susceptible to the
disease.
Birds over 8 weeks are resistant to
challenges and will not show clinical signs unless infected by highly virulent
strains.
Infection is through oral-fecal route
(when the bird ingests contaminated faeces).
Acute disease and death is due to the
destructive effect of the virus on the host tissues.
Kidney failure is a common cause of
death in affected bird.
If the bird survives, it remains
immunocompromised which means it is more susceptible to other diseases.
Clinical signs:
1. Disease may
appear suddenly and spread typically reaches 100%.
2. Mortality
commences on the third day of infection, reaches a peak by day 4, then drops
rapidly, and the surviving chickens recover to a state of apparent health after
5 to 7 days.
3. In the acute
form birds are prostrated, debilitated and dehydrated.
4. They produce a
watery diarrhoea and may have swollen vent stained with faeces.
5. Most of the
flock is recumbent and have ruffled feathers.
6. Mortality rates
vary with virulence of the strain involved, the challenge dose, previous
immunity, presence of concurrent disease, as well as the flock's ability to
mount an effective immune response (from vaccination).
Treatment and Control:
1. Breeder flocks
may be immunised against IBD so that they would transfer protective antibodies
to their progenies, such as broiler and pullet chicks.
2. Low-attenuated
vaccine strains may cause damage to the bursa of Fabricius and
immunosuppression in susceptible chicks.
3. Biosecurity
with adequate restriction to farm visitation and distancing from other flocks.
4. Post outbreak
hygiene measures may not be effective as the virus can survive for long periods
in both housing and water.
5. The virus is
sensitive to sodium hydroxide (it is totally inactivated when pH exceeds 12),
but it is not affected at pH of 2.
6. The iodinated
and chlorinated derivatives, as well as the aldehydes (formaldehyde,
glutaraldehyde) are also active.
Prior to cleaning, all insects and
pests (e.g. rats and mice) must be eliminated as soon as the farm premises are
empty.
Old bedding and dung must be eliminated
and composted.
All farm equipment must be disassembled
and stored in cleaning rooms located outside the farm buildings.
The buildings, surroundings and farm
equipment must be dry-cleaned first, in order to eliminate dust, and then
washed using hot water with a detergent.
A second disinfection of the full
premises must be performed before the introduction of the chicks.
Feeders must be emptied completely and
cleaned.
Under no circumstances may feed remains
from previous flocks be reused.
Disinfection is to be undertaken only
after all the buildings have been cleaned.
All disinfectants are more active at a temperature above 20°C; however, chlorinated and iodinated disinfectants cannot be heated above 43°C.
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