basic information with some field expose by IB

1. Infectious bronchitis

2. History
 The disease was first described in 1931 in a flock of
young chickens in the USA. Since that time, the
disease has been identified in broilers, layers and
breeder chickens throughout the world. Vaccines to
help reduce losses in chickens were first used in the
1950s.

3. Introduction
 Avian infectious bronchitis (IB) is an acute and highly
contagious respiratory disease of chickens.
 It is caused by avian infectious bronchitis virus, a
coronavirus.
 The disease is characterized by respiratory signs
including gasping, coughing, sneezing, tracheal rales,
and nasal discharge.
 In young chickens, severe respiratory distress may
occur.
 In layers, respiratory distress, nephritis, decrease in egg
production, and loss of internal egg quality and egg
shell quality are reported.

4. Occurrence
 IB has been reported as a disease only in chickens.
 All ages of chickens are susceptible to infection, however,
clinical disease severity varies.
 IB is considered to be worldwide in distribution.
 The incidence is not constant throughout the year, being
reported more often during the cooler months.
 Increase age ,increases resistant

5. Etiology
 IB is caused by a coronavirus. It is an enveloped, single-
stranded RNA virus.
 IB virus has the ability to mutate or change its genetic
makeup readily

6. Transmission
 IB virus is spread by the respiratory route in droplets expelled during
coughing or sneezing by infected chickens.
 Spread of the disease through a flock is very rapid.
 Transmission from farm to farm is related to movement of contaminated
people, equipment, and vehicles.
 Following infection, chickens may remain carriers and shed the virus for
several weeks.
 Egg transmission of the virus doubtful.
Horizonta
l
Vertical

7. Clinical sign
 Baby chick showing signs of gasping
and respiratory distress. Other signs in
young chicks often include coughing,
sneezing, rales and oculo-nasal
discharge.
 In most strains, mortality is usually
negligible unless complicated by
secondary bacterial infections.
 However, chicks less than 2 weeks old
that have a natural IB infection or a
severe reaction to IB vaccine, may
suffer permanent damage to the
oviduct, resulting in poor to no egg
production capacity later in life.

8.  In young birds infected with
infectious bronchitis virus (IBV),
some of the earliest signs of the
disease include depression and
ruffled feathers.
 Birds may also huddle near heat
sources.
 These signs typically appear
within 24 hours post-infection.
 Young birds are more
susceptible to IBV than older
birds.

9.  Chronic epiphora (tearing)
associated with infectious
bronchitis virus can lead to
secondary periocular feather
loss, as seen here.

10.  Nasal discharge is more
commonly observed in
infected chicks.
 However, clinical signs of
IBV will vary according to
the pathogenicitiy of the
strain,immune status,
environmental factors, and
the presence of concurrent
infections which may
complicate the disease.

11.  In flocks of birds older than
6 weeks of age, these signs
may be subtle and may only
be observable at night when
the birds are normally quiet.
 This flock of layers is
exhibiting a mixture of
respiratory signs including
coughing, sneezing, and
rales.

12.  A mature chicken exhibiting
depression associated with
infectious bronchitis virus.

13.  Egg color and texture may
also be affected. Here, the
egg shell is roughened and
areas of discoloration are
evident.

14.  When infectious bronchitis
virus replicates in the
reproductive tract of layers,
normal calcium deposition in
the egg shells may be
disrupted, resulting in soft
misshapen eggs.

15.  When the egg is opened, the quality of the egg is often found
to be inferior.
A normal egg is
shown on the
left for
comparison.
As seen in the egg on the right,
the albumen may be thin and
watery and the separation
between the thick and thin
albumen may be absent.

16. Gross lesions
 Here, mild to moderate
inflammation of the trachea and
bronchi can be seen. There is
also an accumulation of white
caseous exudate in the syrinx
and primary bronchi.

17.  In the nephropathogenic
strain of infectious
bronchitis virus, the
kidneys may become
swollen and pale, as seen
here.

18.  These kidneys are swollen
and there is urolithiasis of
the ureters.
 The ureters are very
distended with white
urates.

19. Diagnosis
 On the basis of history.lesion and symptom.
 Serologic procedures commonly used include enzyme labelled
immunosorbent assay (ELISA), virus neutralization, and HI
 Confirmation of IB requires isolation and identification of the
virus.

20. Control
 Prevention of IB is best achieved through an effective biosecurity program.
As a second line of defence, chickens in IB problem areas should be
vaccinated with modified live vaccine.
1. Infectious bronchitis vaccine(Sarabhai Zydus)-freeze dried vaccine
containing attenuated H-120 strain,
2. Live M-48(Hester) massachusetts strain.
3. Nobilis IB(Intervet) H-120 strain.
 Primary vaccination 3-5th day I/O or I/N, booster 28-30th day in drinking
water.
 Revaccination between 90-100 day.
 DOSAGE
 Nasal instillation / eye drop method ……………...0.03 ml per chick
 Drinking water method ……………………………. Sufficient vaccine mixed with
water for birds to be vaccinated.
No. of chicks age in day
 Water(lt)= 1000

21.  1 - 3 weeks Intra ocular (0.03 ml) / drinking water
method
 12 - 13 weeks Drinking water method
 N.B.: Live Avian Infectious Bronchitis (Mass Type
Strain) Vaccine is not to be used after 13th week age
of bird.
 Only Avian Infectious Bronchitis Inactivated Vaccine
is safe after 13`th week and during egg production.