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Infectious Bursal Disease

Gumboro Disease, Infectious Avian Nephrosis

Infectious bursal disease (IBD), also known as Gumboro disease, is an acute, highly contagious, immunosuppressive disease of young chickens worldwide. The disease is caused by the infectious bursal disease virus (IBDV), a type of birnavirus that primarily targets the lymph tissue in the bursa of Fabricius (cloacal bursa). The cloacal bursa plays a significant role in proper function of the chicken's immune system.

Chicks are most susceptible to clinical disease (where they show signs of illness) when they are between 3 to 6 weeks of age. Chicks less than 3 weeks of age are still susceptible to becoming infected with the virus, but typically don't demonstrate signs of illness (subclinical infection). All chicks that are infected with the virus, regardless of whether they demonstrate clinical signs at the time of infection, have lasting impacts. The damage the virus causes to the cloacal bursa results in greater susceptibility to future infections, including normally nonpathogenic microbes.
Infectious bursal disease
When clinical disease occurs, in chicks 3-6 weeks old it is characterized as follows:
  • Has a sudden onset and rapidly runs through all flock members.
  • One of the first clinical signs is watery or whitish diarrhea that clings to the chick's vent feathers (referred to as 'pasty butt'). Sometimes blood is also present. Affected chicks are often seen picking at their own vents.
  • General, non-specific signs such as lethargy, depression, loss of appetite, reduced water intake, huddling, ruffled feathers, and reluctance to stand are often observed in chicks.
  • The diarrhea and reduced water intake will cause dehydration, soon followed by incoordination, trembling and weakness.
  • 20-30% of chicks will usually die 3 days from when they first demonstrated signs of illness.
  • Remaining flock members will usually undergo a rapid recovery 5-7 days from when first infected.
IBDV is spread by direct and indirect contact with infected birds, often through exposure to feces. The virus is able to remain infectious for several months in a wide range of environmental conditions. Once established, it can be very difficult to eradicate.

Incubation period
The incubation period is very short, with clinical signs becoming apparent within 2-3 days following exposure to IBDV.


'Pasty butt'
Whitish or watery diarrhea, sometimes bloody
Chicks pecking at their own vents
Ruffled feathers
Decreased appetite
Reluctance to rise
Unsteady gait


  • History
  • Clinical signs
  • Histopathology of bursae
  • Virus isolation
  • Virus detection in the bursa by immunoassays or RT-PCR
  • AGID or ELISA for antibody detection
  • Virus characterization or neutralization


Report diseaseIn the United States, IBD is a reportable disease, meaning that if you suspect that your chicken has this disease, by law you need to report it to your veterinarian, or a state or federal veterinarian.
Supportive care relating to pasty buttWhen poop hardens it can cause a blockage to the chick's gastrointestinal system, as if the poop has no way to leave the chick's body, the chick will die.
Gather a warm wet facecloth, dry paper towels, and petroleum jelly (Vaseline).
Using the facecloth, gently run it over the hardened poop. The intent is to clean it off completely, but depending on how hard it is this may take repeated attempts and a little time. Once clean, gently dry off the chick's bum with the dry paper towel and apply a small amount of petroleum jelly to the area that was sticky, to try to prevent fresh poop from sticking in the future. Repeatedly check on the chick, as this process is likely to need to be repeated.
Supportive care for dehydration
Protocatechuic acid (PCA)20 mg/kg for 5 days
Thymulin 5cHDiluted into drinking waterSato C et al., 2012
Calendula officinalis extract0.5 ml added to feed daily for for 7 daysS Marina et al; E Barbour et al


  • Vaccination of parent breeders and/or chicks
  • Biosecurity


Surviving chicks remain unthrifty and more susceptible to secondary infections because of immunosuppression.

Scientific References

Good Overviews

Age Range

IBD affects younger chickens less than 6 weeks of age.

Risk Factors

  • Unvaccinated chicks
  • Overcrowded conditions
  • Unsanitary conditions