760 MrCROBIOLOGY OF DISEASES OP MAN AITO DOMESTIC ANIMALS 



The control of the disease depends upon the isolation of the infected 

 animals, cremation of infected foetus, placenta and discharges, and 

 thorough disinfection of the premises. Heifers and healthy cows 

 should not be allowed to mingle with cows which have aborted, nor 

 should they be served by a bull which has covered infected animals at 

 any time. Local antiseptic treatment of the cow which has aborted 

 diminishes the danger of the persisting discharge. 



Contagious abortion also occurs in other domestic animals, espe- 

 cially in horses, sheep, goats and swine. Inoculation experiments have 

 shown that the; Bad. abortus of Bang can infect some of these animals. 

 Its importance as a factor in the epizootics of abortion occurring natu- 

 rally among them is still uncertain. In horses at any rate another organ- 

 ism appears to be more frequently involved. 



Diphtheria* 

 Bacterium diphtheria 



The disease is epidemic in all large communities especially in Europe 

 and America. It is, however, almost absent from tropical regions. 

 Epidemics and pandemics occur in cycles. Essentially diphtheria is a 

 disease peculiar to man. Avian diphtheria, however, is known, al- 

 though seemingly due to another cause, and on rare occasions natural 

 infection has been found in the horse. 



The period of incubation is said to be two to five days. 



In man the disease usually begins with lassitude and fever followed 

 in a few hours by "sore throat." The inflamed area on the pharyngeal 

 wall, tonsils, larynx or wherever it may be becomes in t5T3ical cases the 

 seat of degenerative changes in the epithelium and underlying tissues 

 with abundant fibrinous exudation resulting in the formation of a com- 

 paratively tough membrane or pseudo-membrane, which is a striking 

 and characteristic feature of the disease. This local lesion is almost 

 always found on mucous membranes though occasional instances of 

 infection of wounds have been noted. 



The bacterium of diphtheria was described in 1883 by Klebs in 

 sections of t3T)ical membranes. The organisms were isolated and dif- 

 fertntiated in 1884 by Loeffler, who was able to fulfill Koch's postulates 

 for pathogenic microbes. Accidental infection of the human being has 



• Prepared by Edward Fidlar. 



