CHAPTER XVI 



INFECTIOUS DISEASES OF UNKNOWN CAUSE 



Smallpox (Variola), Hydrophobia (Rabies), Scarlet 

 Fever, Measles, Whooping Cough, Mumps, Yellow 

 Fever, Typhus Fever, Rocky Mountain Spotted 

 Fever, Epidemic Infantile Paralysis. 



Among the common transmissible diseases are a 

 number which have been the subjects of research 

 and experiment continuously since the founding of 

 the science of bacteriology, but which yet must 

 be listed as of unknown origin. 



Smallpox, or Variola 



Smallpox is an acute, infectious, highly conta- 

 gious, eruptive disease. The eruption passes through 

 three stages, (1) papular, (2) vesicular, and (3) 

 pustular, and finally heals with a scab. Like most 

 eruptive diseases, smallpox is especially contagious 

 during the period of desquamation. Several micro- 

 organisms, have been found in the lesions of small- 

 pox, but none have been proved to be the cause of 

 the disease. 



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