Avian Mass Immunization for Infectious 

 Bronchitis and Newcastle Disease 



By W. R. Du nlop and R. G. Strout=^ 



Introduction 



THE PHENOMENAL growth of the poultry industry in the last 

 decade, manifested in size of flocks rather than in number of flocks, pre- 

 sents the need for an entirely new approach to poultry disease control. 



Areas of heavy poultry populatidu lend themselves, unfortunately, to 

 rapid spread of acute diseases. An example of this is readily observed in the 

 prevalence of respiratory conditions, such as infectious bronchitis and New- 

 castle disease. The control of the diseases over the entire country presents a 

 very pressing problem. In spite of the highly specialized technicjues of vac- 

 cinations carried on today, this problem is increasing in magnitude. 



It is apparent that in keeping pace with the industry of today, a method 

 of mass immunization is needed. The arduous task of vaccinating individual 

 birds not only presents an expensive labor problem but also invites a factor 

 known as human error. This factor is considered by some to be largely re- 

 sponsible for the inadequacy of avian immunization programs. 



Mass immunization, whether a dust or a spray, is based on one of the 

 soundest principles in the study of the spread of virus diseases. Specifically, 

 it is understood that most virus diseases of the respiratory tract are spread 

 by means of the virus particles riding on dust particles or moisture droplets 

 in the air. 



Review of Literature 



In 1948, Hitchner and Johnson (7) reported the use of the Bj strain of 

 Newcastle virus in the intranasal vaccination of day-old chicks. While the 

 duration of immunity was not established, day-old vaccinated chicks were 

 immune at 4 months of age. It was also demonstrated that the vaccinatio;i 

 of laying birds did not produce any marked drop in egg production. At- 

 tempts to immunize baby chicks by atomization of the Bj virus resulted in 

 a high morbidity and mortality, but there was no evidence of paralytic 

 symptoms. 



Later, Bankowski ( 1 ) concluded from laboratory and field vaccination 

 trials with an attenuated Newcastle virus that the length of exposure to V:W 

 air-borne virus and the age of the chickens being vaccinated are important 

 considerations. The results were of a highly encouraging nature. 



* Dr. Dunlop is Research Poultry Pathologist and Mr. Strout is Assista-it 

 Pathologist, New Hampshire Agricultural Experiment Station. 



