8o8 MICROBIOLOGY OP DISEASES OF MAN AND DOMESTIC ANIMALS 



The essential features of hog cholera may, be briefly summarized as 

 follows: Extreme contagiousness. Symptoms of severe illness accdm- 

 panied by fever, loss of appetite, weakness and diarrhoea. Haemor- 

 rhagic lesions in the various organs and lymphatic glands and round 

 button-Hke ulcers in the .large intestine. Immunity in hogs which 



recover. 



Fig. 1 7o.^Hemorrliagic points on kidneys of hog-cholera hog. (Original.) 



The etiology of hog cholera has long been the subject of scientific 

 controversy, but it is now generally acknowledged that the cause of 

 this disease is an invisible microorganism which exists in the blood, 

 the internal organs, and the urine of infected hogs. The fact that 

 this disease is caused by an invisible microorganism was demonstrated 

 as follows :* 



The blood serum of hogs infected with hog cholera acquired in the 



* Bulletin 72, Bureau of Animal Industry, U. S. Dept. Agriculture, 1905. 



