Infectious Bursal ( Gumboro) Disease is an acute highly contagious disease of young chicks (2-6 weeks old). It also affects chicks of 7-10 weeks in mild manner. Older birds do not develop clinical disease.
The disease is associated with severe damage to Bursa of Fabricius in young chicks. This leads to defective immune systems, making chicks susceptible to many diseases like Ranikhet ( Newcastle) Disease inspite of vaccination.
The disease spreads by contaminated feed, water and air. The incubation period is short (2-3 days). The affected chicks become dull, depressed, go off feed, have ruffled feathers and huddle in corners. Soon diarrhoea develops leading to progressive weakness & death in 5-6 days. It can affect 80% of the flock but kills about 2-10% chicks only.
On postmortem, bursa is enlarged, oedamatous and yellowish. At times bursa show petechial or ecchymotic haemorrhages on mucosal surface. Occasionally, extensive haemorrhages through the entire bursa are observed. Pinpoint haemorrhages can be seen in muscles of breast, thighs and legs. Spleen is enlarged, caecal tonsil and thymus are hyperemic.
The vaccine contains live, low passage Infectious Bursal Disease Intermediate plus strain virus propagated in SPF chicken embryo fibroblast cell culture. The vaccine virus(serotype 1) successfully immunizes the chicks with maternal antibodies yet is nearly harmless to the Bursal tissue & confers quick immunity against virulent IBD virus. It is available in freeze dried form. The vaccine contains atleast ≥103TCID50 of virus per dose. The vaccine is available in 100, 200, 500 and 1000 dose vial.
METHOD OF VACCINATION :
- Use 4 ml diluent for 100 dose, 8 ml for 200 dose, 20 ml for 500 dose and 40 ml for 1000 dose vial of Gumboro vaccine.
- Remove 1 ml vaccine diluent with a syringe and needle from the diluent vial & reconstitute the vaccine.
- Remove reconstituted vaccine and mix with remaining diluent.
- Administer to the chick one drop of reconstituted vaccine orally .
- The vaccine can also be given in cold non-sanitized drinking water stabilized with 2 gm skimmed milk powder per liter of water. Use enough water that the chicks can drink in 1 to 2 hours. The chicks are kept thirsty for 2-3 hours before offering vaccine water. Vaccination should preferably be done during motning hours.
Chicks should be vaccinated at 12-14 days of age and repeated at 4 weeks of age .
Vaccine should be stored at 20– 80C, in refrigerator. Vaccine diluent can be stored at room temperature in cool area.