Pathogenesis. 265 



and has a great share in the development of the organic affec- 

 tions which develop in association with the primary affection. 

 According to Dorset, McBryde and Bolton the following factors 

 proved that this organism is not the primary cause of hog 

 cholera: 1. The artificial transmission of the disease can be 

 much more readily affected by blood from an affected animal, 

 than by subcutaneous injection of pure cultures of the bacillus 

 suipestifer. 2. Hogs which were affected either by natural 

 infection or by subcutaneous injections with virulent blood 

 transmit the disease very readily to healthy animals, whereas 

 animals which were infected with cultures of bacilli do not infect 

 healthy hogs. 3. Blood from hogs which have been infected with 

 blood, proves virulent by subcutaneous injection, while the blood 

 from hogs infected with cultures of the bacilli is harmless for 

 healthy animals. 4. Recovery from the natural or the artificially 

 produced disease confers a lasting immunity, whereas hogs inoc- 

 ulated with the bacillus suipestifer continue to be- susceptible to 

 the natural infection. 



Besides these considerations it should also be noted that the bacillus 

 suipestifer cannot be demonstrated bacteriologically in all eases of true 

 bog cholera. Thus Uhlenhuth found the organism only in 76 out 

 of 178 affected hogs, while in the other cases in seven so called varieties 

 of this organism (some of which do not ferment dextrose) three times 

 varieties resembling the paratyphus A-Group, once the bacillus en- 

 teritidis Gartner, 50 times the bacillus pyocyaneus, 36 times streptococci, 

 27 times staphylococci, and 110 times colon bacilli, were isolated from 

 the organs ; ' while in 14 cases the organs proved sterile. In some of 

 the outbreaks the bacillus appears to occur only rarely, as Boxmeyer 

 in Michigan and Theiler in South Africa failed to demonstrate the 

 bacillus in typically affected hogs. These findings make it probable 

 that in different localities various bacteria, especially of the paratyphus 

 B, or of the hog cholera group, may produce the usual changes in the 

 intestines found in hog cholera. 



According to views accepted at the present time the bacillus 

 suipestifer forms a group in common with the bacillus paratyphi B 

 and Bac. botulinus, which are pathogenic for man, also including the 

 mice typhus and the psitticosis bacillus, as well as the Bac. Sanarelli. 

 This group is designated as the hog cholera, or the paratyphus B-Group, 

 and the various organisms of this group cannot be distinguished from 

 each other, either by their morphologic and culture characteristics, or 

 by sero-diagnostic methods (agglutination). The only distinguishing 

 signs consist, excepting when their origin may be demonstrated, in 

 certain, not constant, and therefore not characteristic pathogenic prop- 

 erties. The very close relation which almost borders on identity, would 

 explain in hogs, for instance, why it is that various representatives 

 of this group may produce very similar pathological changes, and 

 attain pathogenic properties for man (this theoretical possibility has 

 not yet been proven for the true suipestifer bacillus). Bang and Th. 

 Smith, also Uhlenhuth and his co-workers cultivated strains of the 

 bacillus suipestifer from hog cholera pigs, which showed certain 

 deviations from the common type, and therefore are considered as 

 varieties (some strains produce no gas in dextrose, others coagulate 

 milk, and Smith & Moore even described a non-motile variety). 



