208 SWINE DISEASES 



from different strains of the different species of the repre- 

 sentatives of the hemorrhagic septicemic group would 

 be more efficient. 



Immunization by means of a serum prepared by 

 repeated injections of a horse with cultures of the Bacillus 

 suisepticus has been found partially successful, but the 

 immunity thus produced was apparently of short dura- 

 tion. This method of immunization will probably not 

 come into general use. 



NECROBACILLOSIS 



Necrobacillosis is a name for a group of diseased 

 conditions caused by the Bacillus necrophorus and char- 

 acterized by inflammation and necrosis. This condition 

 is of common occurrence in one form or other in various 

 locations in the United States and in other countries. 

 The state of Colorado has suffered extensive losses from 

 necrobacillosis; in fact, according to Glover, the losses 

 from this disease in that state prior to 1912 were greater 

 than the losses from cholera. The disease occurs sporadi- 

 cally, enzootically, and rarely as an epizootic. 



Etiology. The Bacillus necrophorus is the cause of 

 necrobacillosis. This microorganism is universally dis- 

 tributed, though the intestinal tract of swine may be its 

 natural habitat. The Bacillus necrophorus is pleomor- 

 phic, but usually occurs in long threads in cultures and 

 in the invaded tissues. It contains granules, particularly 

 in old cultures. It is nonmotile and does not form spores. 

 It is a strict anaerobe and grows well in serum agar, 

 bouillon, and milk. A pungent, disagreeable odor is 

 evolved from the cultures, and may also be recognized 

 in the lesions. It stains readily with practically all of 

 the aniline dyes but not with Gram's stain. 



The Bacillus necrophorus produces disease by products 

 that it elaborates and eliminates into the tissue. This 

 microorganism is pathogenic for practically all animals; 

 but as a rule it is only a secondary invader, the tissue 

 resistance having been diminished by previous disease 

 process or by injury. Inoculations of cultures of the 



