BIRD POX VACCINES AND BACTERINS 



209 



Interpretation 



1. The filtered virus produced pox, roup, and avian diphtheria, indicating 

 that one and the same virus is capable of causing- all forms of the disease. 



2. Bird No. 2 had a simple catarrh when inoculated. This evidently low- 

 ered the resistance of nuicous membrance surfaces and avian diphtheria 

 followed. 



3. The incubation period of the filtered virus was from twelve to eighteen 

 days, while in the case of the unfiltered virus it ranged from seven to nine 

 days. The filtered virus also produced a less pronounced form of the infec- 

 tion than did the unfiltered virus. These latter two points coufirm the work 

 of Schinid (8) in 1909. 



A bacteriological examination of the unfiltered powdered virus revealed 

 •several secondary invaders, such as Pseudomonait aermjinosa and variovis 

 Staphylococci. These organisms undoubtedly assisted the unfiltered virus in 

 causing a shorter period of inculiation and a more pronounced form of the 

 disease. 



The Uxiformity of the Virulence of Commercial Viruses. 



Before studying the efficiency of the powdered pox virus vaccines, it was 

 desirable to ascertain the strength of the viruses which make up these com- 

 mercial products. 



Four groups of birds were inoculated on October 5th with four different 

 strains of powdered pox virus. The course of the disease subsequent to the 

 inoculation is represented by the respective lines A, B, C, and D in the fol- 

 lowing graph. Virus A was obtained on October 1 from a natural infection 

 in Massachusetts and viruses B, C, and D were of commercial origin. 



+ + + 



Days 5 6 7 8 9 ]D H 12 B It 15 1« 17 18 19 20 21 22 23 at 25 26 27 28 29 30 31 1 2 3 4 5 6 7 



Chart I. Variance in Streng-th of Powdered Pox Viruses. 



-|- Period of incubation. 

 -|--|- Appearance of a few or several well formed pox nodules. 

 -|--|--]- Appearance of many pox nodules of mature develo])ment. 

 -|--|--j--|- Maximum development of pox nodules. 

 Downward curves — Periods of recovery. 



Virus A showed the greatest potency. The period of inculiation was seven 

 days, the disease reaching its maximum development three days later, and 

 death following within twenty-three days with no appreciable evidence of 

 recovery. 



Virus B showed the greatest potency of the three commercial stock viruses. 

 The period of incubation was eight days, maximum development four days 

 later, and complete recovery in twenty-two days more. 



