INFECTIOUS DISEASES 325 



diagnosis should be done by laboratory procedure. The enlarged and 

 engorged spleen is apparently the outstanding lesion. 



Treatment. — Treatment in the acute attacks has not proved suc- 

 cessful. A bacterin made from the paratyphoid B. has been reported 

 as valuable in preventing this disease, and according to some this 

 bacterin has been successfully used in the subacute form of the disease. 



Salmonellosis 



Salmonellosis is the name of a disease of «wine caused by the B. sui- 

 pestifer. The occurrence of a disease caused by the B. suipestifer 

 has been experimentally demonstrated ; however, the actual occurrence 

 of the disease as a distinct entity is difficult to identify. It is possible 

 that the condition now designated as infectious necrotic enteritis and 

 attributed to various microbian agents will be demonstrated to be 

 salmonellosis. The significance of the B. suipestifer is not fully appre- 

 ciated by practitioners and many investigators, but it is no doubt an 

 important factor in the diseases of swine. 



Malignant Edema 



Malignant edema is a specific infective disease caused by the 

 Bacillus edematis maligni. Pasteur described this disease in 1878 and 

 it was later investigated by Koch and others. 



This disease is relatively common in swine, although reports of 

 cases in literature are rare, probably because of the failure to recog- 

 nize the disease. Porcine malignant edema occurs most frequently as 

 a sequel to immunization with anti-hog cholera serum, castration or 

 other surgical operations. Cases of malignant edema occurring in 

 recently immunized swine have been observed in which 50 per cent 

 of the immunized swine died. The disease has also been observed in 

 swine that had been hyper immunized for serum production and it hai? 

 also been reported to occur in virus pigs in serum establishments. 

 Some sporadic cases of malignant edema have been reported or af 

 least the B. edematis maligni were isolated from lesions. 



Etiology. — The specific cause of this disease is the B. edemati? 

 maligni, an anaerobic spore-bearing microorganism. These micro- 

 organisms are found in the soil and also occur in the digestive tract of 

 some animals. They are distinct bacillary microorganisms when iso- 

 lated from the tissue of an affected animal, but they grow into long 

 filaments after the death of an infected animal and in artificial culture 

 media : 



