Ibd Final

INFECTIOUS BURSAL DISEASE  Highly contagious –young chickens Characterised by • Immunosuppression • Mortality- 3 to 6 wks age • Lymphoid organ –bursa of fabricius destruction.

 Nomenclature: Birna -bi +rna -double stranded RNA virus. o

Family

: birnaviridae

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Genus

: avibirna virus

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Species

:infectious bursal disease virus

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Acronym : IBDV  Virus morphology: -virions non enveloped -bisegmented genome -hexagonal icosahedral symmetry.

 Serotypes: - 1 and 2 • Serotype 1 -young chickens • Serotype 2 -no clinical signs

 Antigenic property: - No HA

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Physicochemical property: 1. Resistant to : Acid pH 3 to 7 Alkali pH 7 to 9 2. Virions not sensitive to treatment with heat (60 C, one hour) or ether. 3. Sensitive to pH below 3 & above 9.

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CULTIVATION: Chickens , ECF, CEF.

1. CHICKENS: -not recommended. -via eyedrop. -kill chicken 72 to 82 hrs after inoculation. 2. Embryonated chicken eggs: -route of inoculation (i) Yolk sac -5 to 7 days (ii) Chorioallantoic membrane – 12 days.

 specific lesions • Dwarfing of embryo • Kidney, liver ,spleen- enlarged. • Congestion and subcutaneous oedema. 3.cell culture: • Chicken embryo fibroblast used.

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Epidemiology :

• -infection oral route. • spread by fomites. • carrier state vertical transmiision not demonstrated.

 PATHOGENESIS Host: Chicken, turkey and ducks Route of transmission: Water, feed , infected birds droppings Carrier : Meal worm and Aedes vexan (Mosquito) Morbidity – 100 % Mortality - broilers 25% - layers 60% Incubation period : 2-3 days. Ingestion ↓ macrophages and lymphoid cells in Caeca

Duodenum Jejunum ↓ liver via portal circulation ↓ bursa of fabricius ↓ Replication in cytoplasm ↓ Target cell – B lymphocytes ↓ Destroys lymphoid follicles in the bursa of fabricius

SYMPTOMS • Self vent pecking • Anorexia • Depression • Trembling • Watery and whitish diarrhea • Prostration • death. • Recovered birds – atrophied bursa of fabricius LESIONS 1.Bursa of fabricius a.swollen & haemorrhage b.atrophy. 2.Dehydrated carcass

3.haemorrhagic dark skeletal muscles 4.Swollen liver and kidneys 5.Intestines with increased mucus

DIAGNOSIS: 1. Clinical symptoms 2. lesions. 3.

Isolation and identification: a. Clinical materials: 1. Fresh bursa and spleen 2. HP-Samples of bursa, spleen, intestines, liver and kidney in neutral buffered formalin. 3. Serology-Blood samples

3.Serological tests 1. AGID 2. Quantitative AGID test. 3. Virus neutralization test 4. ELISA 5.FAT

4.serotype differentiation - employing specific monoclonal antibodies • Cross neutralization test. • Virus neutralization test. • Serological test .

DIFFERENTIAL DIAGNOSIS • Marek’s diseases, • Mycotoxicosis, • coccidiosis, • Haemorrhagic syndrome, • Avian adenovirus infection • Infectious bronchitis.

TREATMENT: Not effective

IMMUNITY 1. VACCINES: IBD vaccines prepared serotype 1 IBDV only.

a. Live vaccines: Only healthy birds should be vaccinated. 1.Mild –fully attenuated(lost its virulence but retained immunogenicity) 2. Intermediate – partially 3.Intermediate plus -not attenuated

Application -8 wks - Intramuscular injection - Spray –aerosal - Drinking water directly added.

b.Inactivated vaccines: 1.breeder hens – only healthy birds vaccinated. 2.produce high, 3.long lasting . 4.uniform levels of antibodies.

ERADICATION: • Recovered and vaccinated shed virus for long periods. Hence disease control

• depopulation • rigorous disinfection of contaminated premises. • Disposal of litter, dead birds, used gunny bags, curtains by incineration or deep burial with slaked lime. ZOONOTIC IMPORTANCE: Not report