Calf Diphtheria. 



419 



Simultaneous inoculations with serum of highly immunized sheep 

 (4 ee.), and with virulent blood (2 cc.), gave very favorable results in 

 a herd of 295 merino sheep. A mixture of serum and virus (2 :1) is also 

 suitable for immunization. Theiler observed that in serial inoculations 

 of sheep the virulence diminishes gradually and finally from the tenth 

 operation, and from then on, a harmless vaccine is obtained. 



Literature. SpreuH, J. of comp. Path., 1905, XVIII, 321.— Paine, Ibid., 1906, 

 XIX, 5.— Theiler, Schw. A., 1895, XXXVII, 1: Bull. P., 1905, III, 617; Z. f. Tm. 

 1907, XI, 301. ' 



4. Calf Diphtheria. Diphtheria vitulorum. 



{Angina diphtheritica vitulorum.) 



Calf diphtheria is an acute infectious disease of sucking 

 calves, in the course of which croupous diphtheritic pseudo- 

 memhranes form on the mucous membrane of the mouth and 

 the pharynx, and which, as a result of a general septic infec- 

 tion usually results in death. The causative factor of the dis- 

 ease is the bacillus necrophorus, which was closely described 

 by Bang. 



History. The disease was first described in 1877 by Dammann, 

 who observed it in enzootic extension in two consecutive years on an 

 estate near the Bast Sea. He established its contagious and transmissible 

 nature and considered it identical with diphtheria of man. Later 

 Blazekovic and VoUers observed similar affections, while Loffler (1884) 

 proved by histological examinations that the affection differed from 

 human diphtheria, and was probably caused by long rods, which were 

 present at the border of the necrotic tissue. Later Bang (1890) estab- 

 lished the identity of the Lofflier's bacillus with his bacillus necrophorus. 



Occurrence. According to the observations made up to 

 the present time the disease occurs but rarely; in some localities 

 however it occurs as a stable disease 

 among the sucking calves and causes 

 by its malignant course material loss. 

 Thus in Dammann 's case all calves 

 born in the winter and spring became 

 affected, and with a few exceptions 

 they died of the affection. 



Etiology. The bacillus necro- 

 phorus, Bang, which is considered to 

 be the cause of the disease, appears as 

 a thin slender rod, which in the tis- 

 sues as well as in artificial cultures, 

 grows into long threads, the plasma of 

 which is either homogeneous or at 

 uniform distances contains dark, fine 

 granules (Fig. 64). The bacillus shows no motility. 



Staining. The bacillus stains only slightly and uniformly with 

 aqueous solutions of aniline dyes, stains well with earbol-fuchsm, but not 

 with Gram. 



]?ig. 64. Bacillus necrophorus 



Bang. Agar culture; staining 



with metliylene blue. 



