28 MASS. EXPERIMENT STATION BULLETIN 273 



State. While these laboratory records, as.sociated with the diagnostic 

 service, do not give the total number of cases for any period, they show 

 that the disease has existed in Masachusetts for at least ten years, and 

 during this time has been progressively advancing into new territory. 



It should be pointed out that the specimens sent to the laboratory were 

 almost entirely from localities in which infectious trachitis had not been 

 reported in previous years. Apparently each specimen represented a new 

 enzootic center, in which the disease was not recognized, and poultrymen 

 took advantage of the laboratory for diagnosis. In tliis way, it was 

 discovered that at least seven new enzootic centers iiad developed each 

 year for the last ten years. The mortality observed by reliable poultry- 

 men in individual flocks under field conditions varied from 5 to 90 

 per cent, depending upon the age, condition, and resistance of the birds. 



Sometimes in flocks consisting of pullets and cockerels, the outbreaks 

 were explosive in character; the disease, in such instances, spread through 

 the flocks in a week or two in spite of all eiforts to check it, took its 

 toll, which was iisually heavy, and disappeared as quickly as it came. 

 In flocks of older birds, such as are commonly kept for breeding pur- 

 poses, the disease often spread slowly and in such flocks was likely to ap- 

 pear sporadically. In some of the birds the infection was acute, while in 

 others it was chronic. Some of the chronic cases showed lesions of pseudo- 

 niembrane in the trachea and larynx for five or six months. In these 

 sporadic appearances of infectious trachitis the mortality usually was 

 low. but the loss in production in most instances was great. 



External factors, such as cold and damp weather, overcrowding and 

 under-feeding, have been held responsible for predisposing flocks to the 

 disease. While these predisposing factors are important in the propa- 

 gation of infectious trachitis. the experiments which follow indicate that 

 the disease is caused by a filtrable virus, and that poultry will not con- 

 tract it unless this causative agent is ])resent. 



The First Transfer of Granby Virus. 



Two field cases of infectious trachitis were sent to the laboratory for 

 experimental purposes on November 20. 1929. Since the flock of origin 

 was at Granby, Massachusetts, the material was designated the Granby 

 Virus, in order to distinguish it from the strains used in other experi- 

 ments. The same day the field cases were received, four White Leghorn 

 cockerels, VP 880, VP 881, VP 882, and VP 884, were inoculated intra- 

 tracheally by means of cotton swabs. White Leghorn cockerel, VP 885, 

 was kept as an uninoculated control. All of the inoculated cockerels 

 developed the disease with the following clinical and pathological histories. 



Five days after inoculation, VP 880 appeared listless, ruffled, inap- 

 petent. and anemic. Slight dyspnea appeared at inspiration. An exam- 

 ination by transmitted light showed pseudomembrane in the rima glottis. 

 The next day, November 26. the dyspneic symptoms were increased and 

 halitosis was very evident. The bird appeared to be weak and spent 

 most of the time off its feet. The seventh day after inoculation, Novem- 

 ber 27, the cockerel was unable to stand. At inspiration the head Mas 

 raised, while the bird gasped for breath with open beak and emitted a 

 peculiar sound as the air was inspired. During expiration the head was 



