Immunization. 289 



always injeeteiT four days after the virus, while each subsequent inoculation is 

 made 12 days after the last. In IV2 to 2 months the horses may be ininiunii.ed 

 to such an extent that they withstand 5 cc. of virulent blood without any reaction. 



The blood necessary for the immunization is taken from affected animals 

 shortly before death, it is defibrinated, filtered, mixed with an equal quantity of 

 glycerin and water, and 5:1000 carbolic acid, and allowed to stand from 2 to 3 

 weeks. After repeated filtration it is stored in small bottles. Immediately before 

 inoculation the required quantity of virus is diluted with 5 cc. of physiological salt 

 solution. 



For the preparation of the immune serum older (salted) horses are injected 

 in the jugular with fresh defibrinated virulent blood at two-weekly intervals (the 

 first time 2,000 cc, later somewhat smaller doses). The blood, which is subsequently 

 drawn, produces the serum, and is preserved by Ehrlich's method (to 90 parts 

 serum 10 parts of a mixture of 5.5 parts carbolic acid, 20 parts glycerin and 74.5 

 parts of water is added). 



Theiler's Method of Immunization. According to Theiler the 

 safest immimization consists in the injection of immune serum (300 cc.) 

 into the juguhir, and virulent blood (1-2 cc.) under the skin; after 

 the appearance of the febrile reaction a second serum injection 

 (50-100 cc.) appears indicated. 



In the Transvaal and Ehodesia 8,766 mules were treated by this method, with 

 a loss of 3.7% from the inoculation. Subsequently only 1.3% fell victim to the 

 disease from natural infection in affected territories. As it has since been found 

 that serum jirepared with a certain virus is sufficiently effective, only against this 

 virus, Theiler recommends the preparation of a polyvalent immune serum. 



Other Methods of Immunization. Rickmann employs material 

 originating from mules which are first injected subcutaneously with 

 0.1 cc. of virulent blood, three days later with 100-200 cc. of serum, 

 and after 12 to 14 days again with 1 cc. of virus (incubation method). 



A second method consists in the simultaneous but separate sul)- 

 cutaneous injection of 0.2 cc. of virus, and 200 cc. of serum, and 21 

 days later the subseciuent subcutaneous inoculation of 25 cc. of virus 

 (simultaneous method). 



According to Eeinecke of 280 mules treated by the first method, and of 160 

 injected by the second method 8% died, and the percentage being somewhat 

 higher in the simultaneous than in the incubation method. Practically all of the 

 inoculated animals remained well, while the losses among the mules which were 

 not inoculated, and kept at the same place, amounted to 3.3% as a result of 

 natural infection. 



Leipziger gives for the first dose subcutaneous injections of 1 cc. of virus, 

 and 300 cc. of highly potent serum; for the second dose 20 cc. of virus. The losses 

 from the inoculations amounted to 3.5%. For the immunization of horses he 

 recommends first the subcutaneous simultaneous method, with 0.1 cc. of virus and 

 400 cc. of serum; three weeks later an injection of 0.3 cc. of virus and 100-200 cc. 

 of serum; then the animals should be injected daily, first subcutaneously, later 

 intravenously, with diminishing quantities (down to 0.01 cc.) and later again with 

 increasing quantities of virus, until a reaction takes place. 



Literature. Theiler, Schw. A., 1893, 145 ; D. t. W., 1901, 209 ; Bull. P., 1905, 

 III, 617; Eep. of the Gov. Yet. Bact., 1905-1908.— Edingtou, The Yet., 1895, XLI, 

 595- J. of comp. Path., 1900, XIII, 223 u. 281.— Eickmann, B. t. W., 1895, 289; 

 A. f. Tk., 1907, XXXIII, 372; B. t. W., 1908, 883.- Sander, A. f. Tk., 1896, XXI, 

 249.— MacFadyean, J. of comp. Path., 1900, XIII, 1; 1901, XIV, 103.— Nocard, 

 Bull 1901 37.— Koch, A. f. Tk., 1905, XXXI, 330.— Eeinecke, Diss. Bern, 1909 

 (Lit.) ; Z. f. Yk., 1910, 76.— Leipziger, Diss. Bern, 1909 (Lit.).— Frei, Z. f. Infkr., 

 1909, YI, 363. 

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