Avian Tuberculosis. 



609 



(Zuern found tuberculosis in 10% of deaths in these animals). 

 Among water fowls the disease, though generally much less 

 prevalent, also appears as an enzootic (Huss). Birds kept 

 in captivity are also affected (M. Koch and Eabinowitsch found 

 118 tuberculous subjects among 459 birds that died in the 

 Zoological Garden in Berlin"). 



Etiology. The bacillus tuberculosis avium obtained from 

 tissues is usually shorter and stains more evenly than the 

 bacillus of mammalian tuberculosis, but otherwise agrees with 

 the latter in staining characteristics (see Fig. 95). 



Cultivation. On glycerin blood serum the bacillus thrives much 

 better than the mammalian variety, glassy, transparent, roundish 

 colonies being visible on the surface of the nutrient medium as early 

 as the 8th and sometimes even the 5th day. Later they become confluent 

 and form a grayish-white or yellowish-red, moist, slimy, stringy, smeary 

 scum that is easily emtilsified in water. The bacillus thrives best be- 

 tween 30° and 40° C, but will grow also at 25° and at 45° C. In 

 cultures grown at a high temperature we find eside from short rods 

 also longer forms that stain uniformly or exhibit a granular appearance, 

 some of them thick and club-shaped or even branched (Maffucci). On 

 potatoes they form a grayish-white, blackish or reddish, moist, smeary, 

 crumpled layer (Matzuschita ; see Plate II); in glycerin bouillon 

 granules develop on the floor and wall of the vessel while only some 

 of the strains form a dry wrinkled membrane on the surface of the 



liquid ("Weber & Boflnger) . On some media, 



e.g., glycerin chicken bouillon, egg yolk, etc., 



occasionally also on ordinary media, the 



_ ^ cultures of some strains present an appear- 



//Mi ' .'^ fTrSlkkf. X £\ ance similar to that of mammalian tubercle 



bacilli. 



Not all tubercle bacilli obtained from birds 

 will show the above culture characteristics, but 

 the greatest variety of transition forms occur, 

 including the dry scaly cultures of mammalian 

 bacilli. (M. KoCh & Eabinowitsch). 



Tenacity. The bacillus of avian tuber- 

 culosis is on the whole more resistant to external 

 infliience than Koch's bacillus. Thus a culture 

 two years old may still contain living bacilli. 

 Temperatures of 70° 0. require 15 minutes to 

 desj;roy them. (Maffucci). 



Fig. 95. Bac. tuberculosis avium. 

 Articular exudate from chicken ; 

 Stain according to Ziehl-Nelsen. 



Pathogenicity. Experimental infection of fowls is most 

 certain by introduction of the virus into the blood stream. 

 One or two months later, upon the appearance of symptoms 

 of marasmus, small tubercles are found in the spleen and 

 liver, while the blood vessels of these organs are filled with 

 masses of bacilli. Intraperitoneal or subcutaneous inoculation 

 give less certain results. These are followed by local foci 

 only, but the affected animal may die from the toxic, effects 

 of the lesion. A single injection of culture masses suffices 

 as a rule for infection. The fowls die after one or two months 



Vol. 1-39 



