Is the Mosquito the only Agent through which 

 Yellow Fever is Transmitted? 1 ) 



I have been requested by my Government to answer the question 

 formulated for the Section on Yellow Fever, in the programme of this 

 Convention: "Is the mosquito the only agent through which yellow fever 

 is transmitted?" and I shall endeavor to do so by linking together the 

 experience of former years with the discoveries of the present day. Taking 

 for granted that all admit that the mosquito does transmit the disease, I 

 suppose that the question will be considered duly answered if I can show 

 that yellow fever is not transmitted, as was at one time believed, through 

 fomites, nor, as has recently been suggested, by other blood sucking insects 

 besides the Stegomyia mosquito. As to the spontaneous generation of the 

 yellow fever infection, independently of a previous case of the disease, I 

 consider that idea as obsolete, having long since been decided negatively 

 by the most competent students of yellow fever etiology. 



The question of fomites as a means of propagating yellow fever is one 

 about which conscientious observers had never been able to agree among 

 themselves and was the habitual battlefield upon which contagionists and 

 anticontagionists waged their fiercest battles during the greater part of 

 the last century. Some twenty years ago, however, the most experienced 

 and clear-sighted epidemiologists in the United States, having at their 

 disposal a vast amount of reliable data, came to the conclusion that the 

 germ of yellow fever, as it is first discharged from the body of a yellow 

 fever patient, was innocuous, and that it only acquired virulent properties 

 when it happened to find an appropriate medium or soil in which it might 

 undergo some intermediate transformations. This ingenious theory was 

 called the "nidus theory", and obtained very general acceptation in the 

 United States, inasmuch as it appeared to meet some of the more obvious 

 difficulties of the problem, while others soon proved to have been left 



1) For the International Sanitary Conference to meet at Washington D. C, 

 Dee. 1-1902. A pamphlet, anil Spanish translation by Dr. E. B. Barnet, Revista de la 

 Asociación Médico-Farmacéutica de la Isla de Cuba, t. III, marzo 1903, p. 245. 



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