THE RELATIONSHIP OF VARIOLA AND VACCINIA 



By P. M. AsHBURN, E. B. Vedder, and E. R. Gentry ' 



{From the United States Army Board for the Study of Tropical Diseases 

 as they Exist in the Philippine Islands ) 



From Jenner's day until the present the relationship of va- 

 riola and vaccinia has been a subject of frequent, often violent, 

 and always unsatisfactory discussion, and no explanation of 

 the relationship has yet received general acceptance. We think 

 that an explanation that is simple, complete, and satisfactory 

 is here presented. The prolonged absence of smallpox from 

 Manila has hitherto prevented our undertaking certain experi- 

 ments that we think might afford definite proof of our view. 

 Therefore, we advance the view, supported by facts already 

 known, and hope that others may be able to do the experimental 

 work, although we shall undertake it in case we can obtain 

 smallpox cases. 



I. BASIC FACTS 



The following basic facts as to the smallpox-vaccinia relation- 

 ship merit first mention. 



1. Smallpox contagion or inoculation gives rise in man to 

 smallpox, a highly contagious, generalized disease of consider- 

 able mortality, characterized ordinarily by a preeruptive stage, 

 and other stages related to the appearance, development, and 

 subsidence of the eruption. 



2. Passed through monkeys and cattle for a few generations 

 and brought back to man, the virus gives rise to vaccinia, a 

 localized, noncontagious, mild disease, that in itself causes no 

 mortality, although septic complications may cause some. 



3. Having, by passage, once lost its power to produce small- 

 pox, the virus nevey- regains it, even though passed from person 

 to person (proper hosts for variola virus) for thirty-five (i) 

 or one hundred(2) (3) years. 



' P. M. Ashburn, major; E. B. Vedder, captain; E. R. Gentry, lieutenant; 

 Medical Corps, United States Army, constituting the United States Army 

 Board for the Study of Tropical Diseases as they Exist in the Philippine 

 Islands. 



115513 2 17 



