IBD infectious bursal disease https://www.udemy.com/course/poultry-farming-viral-diseases-threaten-poultry-industry/?referralCode=EAFBDC5B623DADAAFD25

1. INFECTIOUS BURSAL DISEASE
(IBD; Gumboro Disease)
DEFINITION
Infectious bursal disease (IBD) is an acute, contagious, viral
disease of young chickens characterized by inflammation
followed by atrophy of the Bursa of Fabricius and variable
degrees of immunosuppression.

2. OCCURRENCE
IBD occurs in all of the major poultry-producing countries
of the world. Clinical signs are variable and are generally
more severe in birds 3-6 weeks old.
However, IBD may
occur in chickens as long as they have a functional bursa
of Fabricius (1-16-weeks of age)

3. Birds infected at less
than 3 weeks of age do not have clinical signs.
However,
destruction of the bursa results in
immunosuppression

4. (IBDV) was first described in Gumboro,
Delaware in 1962
, hence the IBDV-related clinical problems and
associated conditions are often referred to as
Gumboro disease

5. ETIOLOGY
IBD is caused by a double-stranded RNA virus
belonging to the genus Avibirnavirus of the family Birnaviridae
The virus is very resistant to environmental factors
and many disinfectants
The virus spreads rapidly

6. It has been demonstrated that IBD can severely
damage the humoral responsiveness of susceptible
chicks when they are infected at less than 3 weeks
of age. Those chicks then do not respond properly
when vaccinated against other diseases

7. Progeny from well-immunized breeder flocks
may resist infection for 2-3 weeks.

8. CLINICAL SIGNS
1. Clinical disease is observed only in birds infected after
3 weeks of age.
There is a sudden onset, particularly
with the first outbreak.

9. tremor
unsteadiness.
There is depression,
anorexia,
ruffled feathers
droopy appearance
Diarrhea and dehydration
voiding of blood and straining

10. Morbidity is very high. Mortality is usually low although
it can be substantial (approaching 30%) if husbandry is
poor or if strains are particularly virulent.
Mortality in a
flock has usually peaked and receded within a week of onset

11. enlarged
Caseous
exudate
ecchymotic hemorrhage.
extensive necrosis
The swelling recedes by the 5th day and the
bursa atrophies rapidly until 8-10 days post
infection

12. Petechial and echymotic
hemorrhages are common in
thigh and pectoral muscles
Hemorrhages at the junction of
the proventriculus and gizzard.

13. Kidneys may be swollen and the ureters may contain urates

14. IBD infection results in immunosuppression, so
birds are more susceptible to secondary infections
such as gangrenous dermatitis, IBH, coccidiosis,
etc. Historically, IBH was preceded by an
immunosuppressive infection such as IBD but recently
IBH has been recognized as a primary disease

15. DIAGNOSIS
In an acute outbreak in susceptible chicks, the short
course and bursal lesions are very suggestive of IBD.
PCR, paired serologic testing with rising titers using
the ELISA, agar-gel precipitin, or virus neutralization
can be used to confirm the diagnosis.

16. CONTROL
. Vaccination of breeders to confer immunity to progeny
is an effective method of reducing the disease in
young chicks. Vaccination programs typically include
“priming” with live vaccines and “boosting” with
inactivated oil-emulsion vaccines to produce high and
long-lasting levels of antibody in breeders.

17. knowledge of passive antibody
levels and correct timing are necessary for successful vaccination
Chicks can be vaccinated against the disease but
timing the vaccination in maternally immune chicks can be difficult