Infectious bronchitis in poultry may be controlled with a regimen that includes priming with at least one live vaccine followed by boosting with an inactivated vaccine, according to Aris Malo, DVM, global technical director for poultry at MSD Animal Health during a recent workshop in Birmingham, England.
The infectious bronchitis virus is persistent and disseminates quickly, making it a continuing menace to the poultry industry, said Malo, and new versions of it emerge often due to the fact that it is an RNA virus and subject to mutations and recombination. According to other studies, layers not vaccinated against infectious bronchitis had over a 70 percent drop in egg production. In contrast, vaccination at three and 16 weeks of age with an inactivated M41 infectious bronchitis vaccine, and without a live primer, resulted in egg-production declines of about 30 percent. A protocol employing a live infectious bronchitis Massachusetts-strain vaccine at three weeks of age, followed by a different live infectious bronchitis Massachusetts-strain vaccine at 16 weeks of age, resulted in a 10 percent drop.
No decline in egg production occurred in birds vaccinated once with a live infectious bronchitis vaccine at three weeks of age followed by an inactivated vaccine at 15 weeks of age. “The best results were achieved when live priming was followed by boosting with an inactivated vaccine,” said Sjaak de Wit, Ph.D., of the Animal Health Service, Deventer, The Netherlands. De Wit said he advocates testing to determine what strains of the virus are circulating and to enable wise vaccine protocol choices.