INFECTIOUS TRACHITIS 53 



exudate of sufficient virulence to cause deatli in susceptible cockerels 

 These chronic carriers had previously suffered an attack of infectious 

 trachitis due to intratracheal inoculation of the Gardner and California 

 strains of the disease, and had recovered from the acute stage in two 

 and four weeks, respectively. They represent 3 per cent of the total 

 puinher of chronic cases examined. If, after every outbreak of infectious 

 1 rachitis. 3 per cent of the birds are carriers for an indefinite period after 

 the acute stage has subsided, it is evident that such flocks are a potential 

 danger to susceptible birds as long as the carrier stage exists. 



From a total of 14-4 birds examined, showing visible symptoms of in- 

 fectious trachitis, the virus was found in either the secretions or excre- 

 tions of 62, or 75.61 per cent. Two of these birds developed into healthy 

 carriers, in which the virus in the tracheal exudate remained viable for 

 two and four weeks after all visible symptoms of the disease had dis- 

 appeared. 



Does Chickenpox Vaccination Protect Against Infectious Trachitis? 



.^ome of the liirds mentioiu'd in ]ut'cecling experiments were reported 

 to have been vaccinated against cliickenpox. As far as could be deter- 

 mined with these birds, chickenpox vaccination did not increase the resist- 

 ance of the birds against infectious trachitis or influence the course oT 

 the disease. Since the chickenpox vaccinations were done outside of the 

 laboratory, and nothing was known about the thoroughness of the work or 

 the effect of the vaccine upon the birds, the results were unsatisfactory. 



In order to get more reliable data on the effect of chickenpox vaccfna- 

 iion against infectious trachitis, nine fowls, four pullets, four cockerels, 

 and four chickens were secured from unvaccinated flocks. These blrBs 

 were vaccinated \\ith a vaccine which had been tested previously and 

 found effective against chickenpox. Every one of the 21 birds showecl 

 lesions of chickenpox within 14 days and failed to react to a second 

 chickenpox vaccination with a different strain of vaccine. 



The nine fowls were treated with Granby virus which possessed marked 

 virulence, and two were killed. 



The cockerels, pullets, and two of the chickens, V 2397 and V 2410, 

 were inoculated with California virus. One cockerel, two pullets, and both 

 of the chickens died as a result of the inoculations. 



Chickens V 2398 and V 2399, after recovering from chickenpox. were 

 tested with the first New Jersey virus and both died. 



All the other birds had severe attacks of infectious trachitis. but re- 

 covered after the disease had run a natural course. 



There was nothing in these experiments to indicate that chickenpox 

 vaccination protected fowls, cockerels, pullets or chickens from infectious 

 trachitis; as a matter of fact, it tended to predispose to infectious trachitis 

 by lowering the vitality of the birds. Apparently chickenpox and in- 

 fectious trachitis are two different diseases symptomatically, pathologi- 

 cally and immunologically. Possibly they are different bacteriologicalTy, 

 since the virus of infectious trachitis did not pass the pores of the Berlie- 

 feld N filter as readily as the chickenpox virus. 



