A SPKCIFIC INFECTIOUS DISEASE I I 



sterilize the skin. In case of traumatic infection the wound 

 itself must be disinfected. 



^ 5. A specific infectious disease. A specific infec- 

 tious disease is the result of the multiplication within the animal^ 

 body of a single species of microorganism. The lesions may 

 be local or general, but the cause producing them is always 

 the same. Thus, Baciermm anthracis will produce a disease 

 which is called anthrax, no other cause can produce it, and no 

 matter how much the lesions may vary in different individuals 

 if they are produced by this species of bacteria the disease is 

 anthrax. It is clear, therefore, that there is no hard and fast 

 line between a simple (single) wound infection and a recog- 

 nized infectious or epizootic disease, except in the nature of the 

 invading organism. The course of the disease may vary in 

 different individuals and usually it does, especially if in differ- 

 ent species of animals. If a man receives accidentlly a cut 

 from a knife with which he is making a post-mortem on an 

 animal dead from anthrax, the lesion is liable to be restricted 

 to the point of inoculation, and while it is anthrax (malignant 

 pustule) it would often be recognized as a simple wound infec- 

 tion. If this accidental inoculation should occur in a guinea 

 pig, the disease would not be recognized as a local lesion ; but 

 the animal would develop septicemia. 



As a class the specific diseases are differentiated from the 

 lesions known clinically as wound infections in a number of 

 ways. The bacteria of the epizootic diseases do not ordinarily 

 produce wound infections following accidental injuries or sur- 

 gical operations, although there are exceptions. Again, there 

 is usually a difference in the mode of infection. The virus of 

 the epizootic diseases is ordinarily introduced through the 

 digestive or respiratory tract or by means of insects, while in 

 wound infection the virus is introduced, as the term implies, 

 through the injured integument or mucosa. 



§ 6. The differential characters of a specific infec- 



■Plants suffer from specific infectious diseases caused by bacteria 

 and fungi, quite as much as animals. 



