Infectious Bronchitis



Infectious Bronchitis

Definition:

Infectious Bronchitis (IB) is an acute contagious viral disease of chickens that usually causes respiratory signs, but may also affect the uterus and kidneys and decrease egg production.

Cause:

IB is caused by a coronavirus.

Incubation Period :

• 18-36 hours

• Rapid spreading and highly contagious.

Transmission :

1. Airborne aerosol from infected birds.

2. Direct contact with short time carriers (about 1 mo.)

3. Contaminated premises (about 1 mo.)

Clinical Signs

CHICKS -

1. sneezing, tracheal rales, nasal discharge and ocular discharge

2. Wet frothy eyes with conjunctivitis - swollen Harderian gland.

3. Depressed

LAYERS -

1. Rales

2. egg production may drop 20-50%.

3. Soft, misshapen and or rough surfaced shells.

4. Shell problems may persist due to prior oviduct infection.

Postmortem Lesions

CHICKS AND BROILERS

1. Hyperemia of trachea

2. Serous exudate in trachea

3. Slight airsacculitis

4. Tracheal plugs at the bifurcation

PULLETS AND LAYERS

1. Hyperemia of trachea

2. Serous & catarrhal exudates of trachea

3. Egg yolk peritonitis

4. Salpingitis & permanently damaged oviduct.

5. Swollen kidneys with urates

Differential Diagnosis

1. Newcastle Disease

2. Laryngotracheitis - slow moving

3. Infectious Coryza - swollen head

4. Avian Influenza

Diagnosis

1. History of fast spreading respiratory disease

2. ELISA - uses Mass. antigen but get cross reaction with other serotypes.

3. HI - less cross reaction early in an outbreak but difficult to interpret later.

4. VN - rises in titer between paired serum samples (2 wks. apart)

5. Isolation and identification of virus-

6. Identification of IBV serotype - PCR, monoclonal antibody test, etc.

Prevention:

Vaccination -

LIVE vaccines - Monovalent - usually Mass

Bivalent - Mass. & Conn

KILLED vaccines - used in breeders and layer pullets to prevent production losses and produce consistently high antibody titers.

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