Infectious Bursal Disease (IBD) is a viral infection that primarily affects young domestic chickens worldwide. The Birna virus causes the disease (Infectious Bursal Disease Virus) and can lead to symptoms such as depression, watery diarrhea, ruffled feathers, and dehydration. Although mortality is usually low, some virus strains can be highly virulent and cause mortality rates of 60% or higher. IBD diagnoses are typically made by examining lesions in the cloacal bursa and identifying the viral genome.
Infectious Bursal Disease Management in Chicken
Causes of Infectious Bursal Disease
- Birna virus is a virus that belongs to the family Birnaviridae and genus Avibirnavirus.
- The virus is highly contagious and persistent in the environment of poultry houses, where it primarily affects chickens.
- Infected birds excrete the virus in their feces for 10-14 days, and the virus can survive in poultry sheds for up to 120 days.
- The virus can remain viable in water, feed, and droppings from infected birds for up to 52 days.
- The virus is known for its hardy nature, as it can survive heat, cleaning, and disinfection procedures.
- It can also survive in the environment between outbreaks, making it difficult to control. Mechanical vectors such as humans, wild birds, and insects can also play a role in transmitting the virus.
Disease Cycle of Infectious Bursal
- Entry: The virus enters the chicken’s body through the respiratory or digestive tract.
- Incubation: The virus incubates for 3-5 days in the tonsils and respiratory and gastrointestinal tract. During this time, the virus replicates and spreads to other tissues, including the bursa of Fabricius.
- Early clinical signs: The first clinical signs of IBD usually occur around 7-14 days post-infection. These signs include depression, huddling, ruffled feathers, and watery diarrhea.
- Immunosuppression: The virus targets and destroys B lymphocytes in the bursa of Fabricius, leading to immunosuppression. This makes the chicken more susceptible to secondary infections by other organisms, such as bacteria and parasites.
- Recovery or death: Chickens that survive the acute phase of the disease may recover but may also develop chronic infections and suboptimal immune function. Some birds may die from the disease, particularly in the case of very virulent strains of the virus.
- Shedding: Infected birds shed the virus in their feces, which can contaminate the environment and infect other birds. This virus can live in the environment for several weeks to months.