LARYNGOTRACHEITIS VACCINATION 15 



These diseases were maintained in healthy birds in the laboratory either by 

 contact or by inoculation with the respective exudates. In making the etiological 

 studies, exudates were streaked on plates containing chicken infusion and chicken 

 blood agar, and incubated aerobically, anaerobically, and in an atmosphere 

 of CO a , or sealed as Nelson (1933) found suitable for cultivating the causative 

 agent in coryza of chickens, and as Delaplane and Stuart (1934), Schalm and 

 Beach (1934), and Eliot and Lewis (1934) found efficacious for isolating an 

 organism involved in purulent conjunctivitis, rhinosinusitis, and colds of chickens. 

 Immunological studies were made on birds recovering from natural attacks of 

 the respective diseases. The diagnostic differentiation of these diseases is es- 

 pecially important because of the bearing it has on vaccination against infectious 

 laryngotracheitis. 



Coryza and Colds 



A gram negative hemophilic bacterium resembling those described by the 

 investigators just mentioned was found in 8 of the 14 diseases classified as corvza 

 and colds. The causative agent in this disease did not appear to be filtrable. 

 Berkefeld V, N, W, and Seitz filters were used according to the technique of 

 Ward (1928), Tang (1932), and Gibbs (1933b). All of the filters used in this 

 study were tested and graded according to the technique of Ward and Tang 

 (1929) and Krueger and Riter (1930). 



The hemophilic bacterium did not appear to be as virulent in chickens reared 

 in the laboratory as in field cases. Other factors such as exposure to cold, damp 

 weather and improper feeding may have been responsible for these differences. 

 Before this microorganism is accepted as the primary cause of coryza and colds 

 in the domestic fowl, more intensive investigations of natural outbreaks are in 

 order. 



Fresh exudate from the nostrils and sinuses of chickens suffering from corvza 

 or colds was swabbed into the bursa of Fabricius and produced mild inflammation 

 of this organ as shown in birds necropsied five days after inoculation. Freshly 

 isolated cultures of Hemophilus gallinarum induced a similar affection, while 

 old laboratory cultures seemed to be quite innocuous. Chickens in which takes 

 were evident retained their resistance to this disease for one month. Hens and 

 roosters, or birds in which the bursa of F*abricius had disappeared, were refractory 

 to this treatment. 



Conjunctivitis 



Five outbreaks of conjunctivitis in chickens six weeks or less in age were 

 found, after several transfers in susceptible chicks, to be chronic eye forms of 

 infectious laryngotracheitis. The poultrymen called this condition "greasy 

 head" because the chickens frequently rubbed their heads on their shoulders, 

 and the head, neck, and shoulders became smeared with exudate from the eyes, 

 producing a very unsightly appearance. 



Rhinosinusitis 



Three outbreaks of rhinosinusitis occurring in Bristol and Plymouth Counties 

 were found upon etiological studies to be due to mixed infections. One outbreak 

 appeared to be due to a combination of ccryza and infectious laryngotracheitis, 



