54. MASS. EXPERIMENT STATION HULI.ETIN 27:3 



Summary 



1. The iiMiiie infectious tracliitis is suji-^ested for tiie disease sonietinie?; 

 called infectious bronchitis, tracheolaryngitis, chicken flu. and Canada flu, 

 because it is short, easily jironounced, and descriptive of the symptoms 

 and chief lesions. 



2. Tiie prevalence of infectious trachitis in Ma.ssachusetts previou.s to 

 1920 and 1921 is uncertain. However, it i.s known that the disease has 

 progressively existed in the State since 1921. 



3. The clinical symptoms of infectious trachitis, as noted in tiiis study, 

 were pale face, ruffled appearance of the feathers, lacrimation of the eyes, 

 elevation of temperature, lack of apjietite sometimes accomjjanied by 

 emesis, cyanotic coloration of the comb and wattles, dyspnea, weakness, 

 the formation of pseudomembranc in the visible ])arts of the respiratory 

 tract, swelling of the infraorbital sinuses, death due to suffocation, toxe- 

 mia, or general debility. 



1-. Gross lesions of infectious trachitis were especially prominent in 

 fowls and absent in young chickens dead of tlie disease. The most common 

 lesions of infectious trachitis revealed by this investigation were descjuama- 

 tive epithelial inflammation of the trachea, the formation of pseudomem- 

 b.rane in the respiratory tract, congestion and sometimes fatty degeneration 

 ol the liver, inflammation of the spleen and liemorrhages of the kidney. 

 Congestion and consolidation of the lungs occurred in a few cases. 



.5. The histopathology of infectious tracliitis varied consitlerably in 

 individual birds. The following lesions were usually found in this study: 

 hyperemia of the trachea, larynx and alidominal organs, des(]uamative 

 inflammation of the ciliated epithelial iayer> of the tracliea and larynx: 

 fil)rino-purident infiltration of the mucosa of the trachea; hemorrhagic 

 infiltration into the aheolar sjiaces of the lungs, tubular spaces of the 

 kidneys, and the mucosa and sidimucosa of tlie tracliea; inflammation and 

 sometimes fatty degeneration of the liver. Inflammation of the sjileen was 

 observed in some cases. 



(). Viruses from acute field cases of infectious trachitis were success- 

 fully jirojiagated under laboratory conditions. \'iruses from chronic field 

 cases of infectious trachitis lost their jiotency when transmitted in series 

 under laboratory conditions. 



7. N'iruses from the acute field cases of infectious Iraciiitis studied 

 i:i this investigation were filtrable. These viruses consistently passed the 

 pores of Berkefeld V and Seitz fdters in sutticient (piantities to success- 

 fully inoculate fowls, ])ullets, cockerels, and chickens. Some of the viruse-; 

 were partially retained by the Berkefeld N filters, used in these exjieri- 

 ments, so that susceptible birds were not always successfully inoculated 

 with the filtrates. These viruses were not demonstrated in the filtrates 

 pa.ssing through Berkefeld M' filters. 



fS. F'owls, pullets, cockerels, arul chickens were not successfully inocu- 

 lated by the subcutaneous method. 



9. Six chickens inoculated intravenously with the virus of infectious 

 trachitis failed to develoj) the disease, while the controls inoculated intra- 

 tracheallv with the same virus died. 



