1878.] Dr. Klein. Etiology of Infections Diseases. 101 



III. " Experimental Contribution to the Etiology of Infections 

 Diseases with special reference to the Doctrine of Contagram 

 vivum." By E. Klein, M.D., F.R S. Received February 4, 

 1878. 



The present communication has for its object to bring before the 

 Royal Society the results of an experimental inquiry * into the etiology 

 of an infectious disease of the pig, known as Hog Plague, Mai Rouge, 

 Red Soldier, Malignant Erysipelas, or also Typhoid Fever of the Pig. 

 There are English and continental writers who describe the disease as 

 Anthrax or Splenic Fever of the Pig. I shall show, however, conclu- 

 sively, in my Report to the Medical Officer of the Local Government 

 Board, that it is neither typhoid fever nor anthrax, but is an infectious 

 disease of its own kind, which I propose to call " Infectious Pneumo- 

 Enteritis of the Pig " (Pneumo-enteritis contagiosa) . 



Like other infectious diseases, the " Pneumo-Enteritis " possesses an 

 incubation period, followed by constitutional disturbance and certain 

 anatomical changes. These latter are invariably affections of the lung, 

 of the intestine, and of the lymphatic glands, not only of those of the 

 organs of respiration and alimentation, but also those of the inguinal 

 and lumbar regions. In the lung the changes are those known to 

 pathologists as lobular pneumonia. In the alimentary canal the 

 mucous membrane of the large intestine is chiefly affected, being the 

 seat of smaller or larger ulcerations. There is generally also inflam- 

 mation of the serous membranes, especially the peritoneum, leading to 

 an exudation of lymph into the serous cavity. The skin is occasionally 

 affected with greater or smaller red patches. 



There are hemorrhagic patches to be found in the lung and serous 

 membranes, the endocardium, and the muscle of the heart, the mucous 

 membrane of the intestine (especially duodenum and large intestine), 

 the tongue, and occasionally also the liver and spleen, only seldom in 

 the skin and kidney. 



In anatomical respects, therefore, the Pneumo-Enteritis bears un- 

 doubtedly a great resemblance to anthrax or splenic fever. There 

 exists, however, a marked difference between the two diseases in the 

 incubation period, the general pathology, f and especially in the ana- 

 tomical character of the spleen and blood. In splenic fever we find the 

 spleen invariably enlarged, being the principal organ of the affection, 



* This being part of a larger research carried out for the medical officer of the 

 Local Government Board. 



+ In splenic fever the period of incubation ranges from between a few hours to 

 several days, in pneumo-enteritis it varies from two to five days and more. Splenic 

 fever is easily transmissible to man and the domestic animals, whereas the transmissi- 

 bility of the pneumo-enteritis is much more limited. Hitherto I have succeeded in 

 communicating it to rabbits, guinea-pigs and mice, although only with difficulty. 



