Gumboro Disease is an actue 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 serve damage to Bursa in Fabricius in young chicks. This leads to defective immune systems, making chicks susceptible to many disease including disease like Ranikhet 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 diarrhea 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 Gumboro 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 It is available in freeze dried form. The vaccine contains atleast ≥102 TCID50 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.
- 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(for 1000 chicks use one litre per day of age e.g. for 10 days old chicks 10-litre water) that the chicks can drink in 1 to 2 hours. After mixing the required number of vaccine doses throughly in the water, the vaccine water is offered to the chicks in clean waterers. 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 10-12 days of age and repeated at 4 weeks of age oral route.
Vaccine should be stored at 20– 80C, in refrigerator. Vaccine diluent can be stored at room temperature in cool area.