604 Hog-cholera 



and that it is from diseased and dead swine that the bacilli 

 are obtained, these animals are not very easily infected 

 artificially. They show no symptoms when injected subcu- 

 taneously, but almost invariably die after intravenous in- 

 jection of 1-2 c.c. of a virulent culture. 



Smith found that feeding with 200-300 c.c. of a bouillon 

 culture after a day's fasting, or with small quantities admin- 

 istered daily, would cause death, with a widespread diph- 

 theritic inflammation of the stomach and colon. Feeding 

 with the organs of dead hogs produces the same lesions as 

 the administration of the culture. 



Immunity. As early as 1886 Salmon and Smith found 

 it possible to produce immunity against hog-cholera in sus- 

 ceptible animals, by gradually accustoming them to increas- 

 ing doses of the bacteria. De Schweinitz isolated from cul- 

 tures of the bacteria two toxic substances, a ptomain 

 (sucholotoxin) and an albumose (sucholoalbumin), to- 

 gether with cadaverin and methylamin. With these sub- 

 stances he seems to have been able to produce immunity. 

 Selander * and Metschnikoff found that immunity could be 

 produced more quickly by the use of blood of infected 

 rabbits exposed to 58 C. This blood was found to be 

 exceedingly toxic. 



De Schweinitz f found that the introduction into cows 

 of progressively increased quantities of hog-cholera cultures 

 caused the development of an antitoxic substance capable 

 of protecting guinea-pigs from the disease. 



After several years of treatment, some horses that I 

 attempted to immunize failed to yield a serum protective 

 enough to be of therapeutic value. To protect a rabbit 

 against fatal infection required several cubic centimeters 

 of the blood. 



McClintock, Boxmeyer and SifferJ found that hogs may 

 be immunized against hog-cholera by the simultaneous 

 injection of diseased and immune blood, the larger animals 

 with great readiness and apparently without danger, while 

 the smaller animals react more violently and some loss is 

 liable to occur. Drying at 37 C. or the addition of 33 per 

 cent, glycerin does not attenuate the virus sufficiently for 

 immunizing purposes. Moderate doses of immune serum 

 show no curative power. 



* See "Centralbl. f. Bakt.," etc., Bd. xi, p. 339. 



f "Centralbl. f. Bakt. u. Parasitenk., " xx, p. 573. 



{ "Jour, of Infectious Diseases," March i, 1905, vol. u, No. 2, p. 374. 



