666 Bacillus Suipestifer 



by the reaction of agglutination. Typhoid immune serum produces some small 

 agglutinations, but a comparison between these and the agglutinations formed by 

 cultures of the typhoid bacillus shows immediately that the micro-organisms are 

 dissimilar. Differentiation is best made out when the prepared hanging-drop 

 specimens of serums and cultures are kept for some hours in an incubating oven. 

 It is not known whether the bacillus is peculiar to the intestines of parrots, invad- 

 ing their tissues when they become ill, or whether it is a purely pathogenic micro- 

 organism found only in psittacosis. 



Bacillus Suipestifer (Salmon and Smith)* 



Synonjrm. — Bacillus cholera; suis. 



General Characteristics. — An actively motile, flagellated, non-sporogenous, 

 non-chromogenic, non-liquefying, aerobic and optionally anaerobic, aerogenic 

 bacillus pathogenic for hogs and other animals. It stains by the ordinary 

 methods, but not by Gram's method. It ferments dextrose, but does not form 

 indol or coagulate or acidulate milk. 



Hog-cholera, or "pig typhoid," as the English call it, is a common epidemic 

 disease of swine, which at times kiUs go per cent, of the infected animals, and thus 

 causes immense losses to breeders. Salmon estimates that the annual losses 

 from this disease in the United States range from $io,ooo,ooo to $25,000,000. 

 For years it was thought to be caused by the Bacillus suipestifer, but DeSchwein- 

 itz and Dorset f were able to transmit the disease from one hog to another in 

 certain of the body fluids that had been passed through the finest porcelain filters 

 and were shown by inoculation and cultivation to be free of bacilli. It therefore 

 depends upon a filterable and unknown virus. 



This observation was received with approval by those who had any experience 

 with the effect of hog-cholera bacilli upon hogs, all of whom must have observed 

 that though infection with the bacilli occasionally caused the death of an animal, 

 the dead animal usually did not show the typical lesions of the disease and never 

 infected other animals with which it was kept. The papers upon the subject by 

 Dorset, Bolton, and McBrydeJ and by Dorset, McBryde, and Niles§ are worth 

 reading. 



These investigations entirely changed our ideas of the importance of the hog- 

 cholera bacillus, whose relation to the disease now comes to resemble that of 

 Bacillus icteroides to yellow fever. 



The bacillus of hog-cholera was first found by Salmon and Smith, |1 but was for 

 a long time confused with the bacillus of "swine-plague," which it closely resem- 

 bles, and in association with which it frequently occurs. It is a member of the 

 group of bacteria to which Bacillus icteroides and B. typhi murium belong. The 

 cirganism was secured by Smith from the spleens of more than 500 hogs. It 

 occurs in the blood and in all the organs, and has also been cultivated from the 

 urine. 



Morphology. — The organisms appear as short rods with rounded ends, 1.2 to 

 i.5« long and 0.6 to 0.7^1 in breadth. They are actively motile and possess long 

 flagella (peritrichia), easily demonstrable by the usual methods of staining. No 

 spore production has been observed. In general the bacillus resembles that of 

 typhoid fever. It stains readily by the ordinary methods, but not by Gram's 

 method. 



Cijltivation. — No trouble is experienced in cultivating the bacilli, which grow 

 well in all the media under aerobic and anaerobic conditions. 



Colonies. — Upon gelatin plates the colonies become visible in from twenty-four 

 to forty-eight hours, the deeper ones appearing spheric with sharply defined 

 borders. The surfaces are brown by reflected light, and without markings. 



* -Annual Report of the United States Bureau of Animal Industry, 1883, Vol. ii. 



t "Circular No. 41 of Bureau of Animal Industry," U. S. Dept. of Agriculture, 

 Washington, D. C. 



t"Bull. No. 72 of Bureau of Animal Industry," U. S. Dept. Agriculture, 

 Washington, D. C, 1905. 



.§"Bull. No. 102 of Bureau of Animal Industry," U. S. Dept. Agriculture, 

 Washington, D. C, Jan. 18, 1908. 



II "Reports of the Bureau of Animal Industry," 1885-91; and "Centralbl. f. 

 Bakt. u. Parasitenk.," March 2, 1891, Bd. ix, Nos. 8, 9, and 10. 



