Prof. R. N. Sreenivas Gowda

Former VC- KVAFSU, Bidar .

Infectious bursal disease is a viral infection, affecting the immune system of poultry.

The disease is highly contagious, affects young chickens, and is characterised by the destruction of the lymphoid organs, and in particular the bursa of Fabricius, where B lymphocytes mature and differentiate.

Why it is called Gumboro Disease?Why it is called Gumboro Disease?Infectious bursal disease (also

known as IBD, Gumboro Disease, Infectious Bursitis and Infectious Avian Nephrosis)

The disease was first discovered in Gumboro,a place in Delaware, USA in 1962, hence the name Gumboro Disease

IBD is a highly contagious disease of young chickens caused by infectious bursal disease virus (IBDV), characterized by immunosuppression and mortality generally at 3 to 6 weeks of age.

B- Lymphocytes are the primary target cells. It primarily affects the bursa of fabricius, an

important organ responsible for immunity.

Why it is Economically Important?

Economically significant, because heavy mortality in 3 – 6 wks old chickens and older and severe prolonged immunosuppression of chickens infected at an early age.

This disease breakdowns the immunity, leading to the outbreak of other diseases.

Immunosuppression leads to vaccination failures, Escherichia coli infection, and Gangrenous dermatitis and Inclusion Body hepatitis – anaemia syndrome.

Economic impact of IBDThe economic impact of an Infectious Bursal

Disease Virus (IBDV) infection is two fold:1.Direct mortality that can reach levels in

excess of 40% to 100%2.Secondary infections, due to a suboptimal

immune system, having a negative impact on production efficiency.

The Cause ? - VIRUS Small, non-enveloped double

stranded RNA virus that has a bi-segmented genome belongs to Genus; Arbirnavirus &Family: Birnaviridae.

Very stable hardy virus. Able to withstand a wide pH

range (pH 2-12). Heat stable (still viable after 30

minutes at 60°C). High level of resistance to most

commonly used disinfectants. Survives in the poultry house

environment for extended periods of time.

IBD- Variants –vvIBD ?At least

six antigenic subtypes of IBDV serotype 1 have been identified by in vitro cross-neutralization assay.

Viruses belonging to one of these antigenic subtypes are commonly known as variants, which were reported to break through high levels of maternal antibodies in commercial flocks, causing up to 60 to 100 percent mortality rates vvIBD in chickens.

There are two distinct serotypes of the virus, but only serotype 1 viruses cause disease in poultry.

TransmissionIn recent years, very virulent strains

of IBDV (vvIBDV), causing severe mortality in chicken, have emerged.

Infection is via the oro-fecal route, with affected bird excreting high levels of the virus for approximately 2 weeks after infection.

Transmission…..cont This virus is highly contagious and persistent in the environment of

poultry houses. Affected birds excrete the virus in faeces for 10-14 days. Virus survives upto 120 days in poultry sheds. Water, feed, droppings from infected birds are viable for 52 days in

the poultry houses. Hardy nature of this virus survives heat, cleaning and disinfectant

procedures. Survives in the environment between outbreaks. Meal worm, Aedes vexan (Mosquito) and litter mites appear to act as

carriers and remains infective for up to 8 weeks. Egg trays, vehicles used in the transport of birds, eggs and personal

handling of birds in sheds and elsewhere are very important source of carriers of infection.

Role of mechanical vectors (Human, wild birds, insects). No vertical transmission and carriers. (Disease is not transmitted

through eggs). Older birds (due to Bursal regression) are more resistant to infection.

Clinical signsDisease may appear

suddenly and morbidity typically reaches 100%.

In the acute form birds are prostrated, debilitated and dehydrated.

They produce a watery diarrhoea and may have swollen faeces-stained vent.

Most of the flock is recumbent and have ruffled feathers.

Field Expression of IBDACUTE CLINCAL IBD SUBCLINICAL IBD

Sudden onset of disease. Infected birds are depressed,

have ruffled feathers, droopy appearance and may be seen pecking at the vent.

Morbidity and mortality begins 3 days post infection, peaks and recedes in a period of 5 -7 days.

Mortality may be negligible or as high as 90% in case of very virulent IBDV. The more common scenario is mortality of 10 – 20%.

In the field situation the mortality in layer type birds is generally higher than in meat type birds.

Characterised by bursal atrophy, immunosuppression and resultant increased susceptibility to secondary infections (such as E. coli).

No peak mortality as evidenced with clinical IBD.

Secondary infections in broilers, mainly E. coli, result in a continuous above standard daily mortality and poorer feed conversions.

Due to immunosuppression there can be a poor response to subsequent vaccinations.

Mortality & MorbidityThis is acute and highly contagious infection

of chickens..Young chicks up to 0-6 weeks are more

susceptible.Incubation period is short and clinical signs

observed in 2-3 days following infection.Morbidity is 100% and mortality is 80-90%.

Clinical signsSelf vent pecking.AnorexiaDepression and

tremblingWatery and whitish

diarrhoeaSoiled ventsRuffled feathersReluctant to moveClosed eyes and death.

Gross lesionsDehydration of carcass.Petechial / paint brush haemorrhages on

the leg, thigh and pectoral muscles.Hemorrhage in the Proventriculus and

Gizzard junction.Enlargement of bursa fabricius to almost

double its normal size.Haemorrhage on the internal and serosal

surfaces of the bursa fabricius.Intestine with excess mucus.

Gross lesions in IBDHemorrhages on the keel muscle

and thigh muscle

Enlarged Bursa

Enlarged and hemorrhgic BF

Hemorrhages at the junction of proventriculus and gizzard

Enlarged BF & congested kidney

Kidney LesionsSWOLLEN CORRUGATED

KIDNEY

DiagnosisFlock HistoryA sudden onset of mortality in chickens between 2 and 8 weeks of age could indicate an IBDV infection. The presence of distinctive lesions in the bursa of Fabricus and accompanying blood spots in the musculature of the breast and thigh of affected chickens are strong indications.SerologyMolecular diagnostic assays are most often used to identify IBDV in diagnostic samples. They use reverse-transcriptase PCR to identify the viral genome in bursa tissue. analysis of the VP2 coding region has been used to further characterize the viruses. Viral IsolationIBDV may be isolated in 8- to 11-day-old, antibody-free chicken embryos with inocula from birds in the early stages of disease.

Vaccine for IBD•Primary vaccination with mild or intermediate strain at 2 weeks of age.•Booster vaccination with intermediate strain (live) after 3 weeks of age.•Recommended vaccination schedule for layer chicks:

Age in Days Name of the Vaccine

Route

12-14 IBD-live (primary)

I/O

22-24 IBD live (Booster)

I/O

Vaccination of Breeders•Vaccination of breeder stock and seromonitoring by hatcheries to ensure adequate levels of maternal antibodies in the chicks.•To obtain high levels of MDA in progeny, parent stocks are vaccinated between 4 and 10 weeks of age with live vaccine and again at approximately 16 weeks with inactivated oil-adjuvant vaccine.

                                                                                                                                                   

Treatment Since it is a viral disease better to have good

vaccination programme for breeders, and chicks

• Include immuno-stimulants like Vitamin E in the feed.

A pinch of salt in a liter of water with vitamin E- is beneficial

Give Mycotoxin free feed

Prevention and controlProper disposable of dead birdsBurry in deep soil layered with lime

• Disposal of litter, dead birds, used gunny bags, curtains and other disposables by incineration or deep burial with slaked lime.

• Restricting vehicular movements with crates, egg trays and culled birds.

• Soaking feeders and waterers with 5% formalin.• Fumigating new poultry sheds with formalin

fumes.• Restricting personnel to their sheds for work

Keep watch on movement of Men and MaterialUsed Egg filler flats

Vectors- Dark beetles & Mosquitos