Dr Bhavesh Zapadia

AN ASSIGNMENT ON

INFCTIOUS BURSAL DISEASE (GUMBORO DISEASE)

BY M. R. VAHORA. M. V. Sc. Student. Livestock Production.

INTRODUCTION.  IBD is an acute highly contagious viral

infection of young chicken.  In 1962 first recognized and referred to as “avian nephrosis”  Since first outbreak occurred in area of Gumbora in U.S.A.called Gumboro disease.  In India first outbreak in 1977-78.

ETIOLOGY  IBDV is a member of the Birnaviridae

family (12,23,87)  Virus is single shelled  Non enveloped virion.  Has two segment (i) Segment A (large) VP2, VP3,VP4. (ii) Segment B (Small) VP1.

PATHOTYPE OF IBDV Main two type of serotypes designated as – Serotype- 1 – Serotype- 2.

Serotype-1.

– (i) Standard serotype –moderate mortality and immunosupression. – (ii) Variant serotype-1 No mortality and high immunosupression.Found in U.S.A. – (iii) Very virulent serotype-1 High mortality and high immunosupression. Found in Asia,Europe.

Serptype-2.

– Found only in Turkey. However later studies show that virus of serotype-2 could be isolated from chicken.

PATHOGENESIS  Field viruses exhibit different degrees of

pathogenicity.  WhiteLeghorne exhibited the most sever reaction and had the highest mortality.  Period of greatest susceptibility is between 3 to 6 weeks.  Susceptible chicken younger than 3 weeks do not exhibit clinical sign but have subclinical infection that are economical important because the result can be sever immunosupression of the chicken.

SOURCE  Contaminated feed and water.  Virus found in high concentration in litter.  If litter is used as mannure in area, more

problem of IBD.

SYMPTOMS  CLINICAL IBD  Anorexia,Depression.  Ruffled Feather  White diarrhoea and Pasty vent.  Spiking or shooting mortality.  Typical mortality curve  Disease of self restricting.

SUBCLINICAL IBD  Immunosupression  Impairment of immune system.

MORTALITY PATTERN  In broiler    

Mortality between 3-6 weeks. 2- 5% mortality rarely goes beyond 10%. Peak on 2nd and 3rd day. No mortality on 5th day.

 In layer Mortality between 5-10 weeks of age. 30- 70 % mortality Mortality runs from 7 to 14 days. Two peak. AT 3rd and 4th day AT 7th and 8th day.  In unvaccinated flock 90% mortality.  In cage layer high mortality.    

P. M. LESION  Bursa oedematous and enlargement with peribursal       

oedema. Mucosal surface of bursa is necrotic and haemorrhagic. Bursal atrophy with caseous material in lumen at the receding phase of outbreak. Bursal lesion are more pronounce in layer than broiler. Diffuse haemorrhage in thigh,leg muscles and breast. Haemorrhage at provetriculus-gizzard junction. Haemorrhage may extend to glandular part of proventriculus. Kidney dehydrated and prominent tubules.

EFFECT OF IMMUNOSUPRESSION DUE TO IBD  Lack of proper response to vaccination.  Poor booster effect of vaccination.  Lower resistance to pathogens like

E.coli.,Mycoplasma.  Increase incidence of IBD related disease like IBH,GDS and CAA.  Supression of growth rate and poor FCR.

TREATMENT AND CONTROL  No effective treatment.  Only supportive treatment.  Reduce dehydration. Give Electrolytes.  Boost immunity.  Give Vit.C, Vit.E,Selenium.

PREVENTION  Vaccination is effective tool.  A universal vaccination program cannot be offered

because of the variability in maternal immunity, management and operational condition that exist.  Also consider past history and prevalence of disease.  IBDV is sensitive to    

0.5% formalin for 6 hours. 0.5% Chloramines –killed virus in 10 minutes. Glutaraldehyde. Alkyldimethylbenzyl ammonium chloride.

VACCINATION SCHEDULE  For commercial broiler.  At 12-13 days age Intermediate plus in drinking water.  For commercial Layer.  On 14th day Intermediate I/O or D/W.  On 21st day Intermediate plus in D/W.  On 28th day Intermediate in D/W.  Other schedule.  On 18th day Intermediate plus in D/W.  On 26th day Intermediate plus in D/W.  For Breeder  Prelay and Midlay Oil Adjuvent inactivated vaccine.