Summary about Disease
Infectious Bursal Disease (IBD), also known as Gumboro disease, is a highly contagious viral disease of young chickens, primarily affecting the bursa of Fabricius. The bursa of Fabricius is a specialized lymphoid organ responsible for the development of B-lymphocytes, which play a critical role in the bird's immune system. IBD causes immunosuppression, making chickens more susceptible to other diseases and reducing the effectiveness of vaccinations.
Symptoms
Depression
Anorexia (loss of appetite)
Ruffled feathers
Diarrhea (often watery and may contain blood)
Vent pasting (fecal matter sticking to the vent)
Tremors
Prostration (lying down and unable to stand)
Swollen vent
Dehydration
Increased mortality
Causes
IBD is caused by the Infectious Bursal Disease Virus (IBDV), a double-stranded RNA virus belonging to the Birnaviridae family. The virus is highly resistant to environmental degradation and can persist for extended periods. Different strains of the virus exist, varying in virulence (ability to cause disease).
Medicine Used
There is no specific antiviral treatment for IBD. Treatment focuses on supportive care to manage secondary infections and dehydration:
Supportive care: Providing easy access to water and electrolytes to combat dehydration.
Antibiotics: May be used to treat secondary bacterial infections that develop due to immunosuppression.
Vitamins: Vitamin supplements may help to support the bird's immune system.
Vaccination: Vaccination is the primary method of prevention and control. Live and inactivated vaccines are available.
Is Communicable
Yes, IBD is highly communicable between chickens. The virus spreads rapidly through direct contact with infected birds or through indirect contact with contaminated environments, including feces, feed, water, equipment, and personnel.
Precautions
Vaccination: Implement a rigorous vaccination program using appropriate vaccines for the local IBDV strains.
Biosecurity: Strict biosecurity measures are crucial to prevent the introduction and spread of the virus:
Restricting access to poultry houses.
Foot baths and hand sanitization at entry points.
Cleaning and disinfection of equipment and facilities.
All-in/all-out management (raising birds of the same age together).
Proper disposal of dead birds.
Good hygiene: Maintaining clean and dry litter, providing clean water and feed.
Vector control: Controlling insects and rodents, which can act as mechanical vectors.
Water Sanitation: Properly sanitize drinking water, to prevent disease spread.
How long does an outbreak last?
An acute outbreak of IBD typically lasts for 1-2 weeks within a flock. Mortality rates can vary depending on the virulence of the virus strain and the age and immune status of the chickens.
How is it diagnosed?
IBD is diagnosed based on a combination of factors:
Clinical signs: Observation of characteristic symptoms.
Gross pathology: Examination of the bursa of Fabricius during necropsy (post-mortem examination). The bursa is typically enlarged, edematous (swollen), and may contain hemorrhages. Later in the disease, the bursa shrinks and becomes atrophic.
Histopathology: Microscopic examination of bursa tissue to identify characteristic lesions.
Virus isolation: Detecting the virus in bursal tissue or feces.
Serology: Detecting antibodies against IBDV in the blood.
PCR (Polymerase Chain Reaction): A molecular test to detect the presence of the IBDV genetic material.
Timeline of Symptoms
Incubation period: 2-3 days.
Initial symptoms: Depression, anorexia, ruffled feathers.
Peak of the disease: Diarrhea, vent pasting, tremors, prostration. Bursa is enlarged and inflamed.
Recovery phase: Surviving birds may begin to recover within a week, but immunosuppression can persist for several weeks. Bursa starts to atrophy.
Important Considerations
IBD can cause significant economic losses due to mortality, reduced growth rates, increased susceptibility to other diseases, and decreased vaccination efficacy.
Subclinical infections (infections without obvious symptoms) can occur, leading to immunosuppression and reduced performance even without high mortality.
Proper vaccination is crucial, but vaccine failures can occur due to the presence of variant IBDV strains or inadequate immune response in vaccinated birds. Monitoring antibody levels after vaccination is recommended.
Biosecurity and hygiene are essential for preventing the introduction and spread of IBDV, especially in multi-age poultry operations.