Yellow Fever 

 Its Transmission by Means of the Culex Mosquito ^ 



In the month of May, of last year, when the yellow fever epidemic was 

 commencing at Vera Cruz, Dr. Carmona, of Mexico, inoculated six 

 prisioners with the dried residue of yellow fever urine. In two of the six, the 

 local symptoms of the inoculation were immediately followed by those of 

 fatal yellow fever, and a few days later, both died on the same day 

 (Carmona, Lecons sur l'étiologie et la prophylaxie de la fiévre jaune, 

 p. 265). This unfortunate result agrees with the views that I have 

 entertained since 1881, viz, that whereas the disease is not spontaneously 

 transmissible by infection through the air nor by contact, it can be 

 communicated by inoculation. In searching for a natural agent capable of 

 fulfilling this condition I was led to fix upon the Culex mosquito as the 

 most likely one. Before submitting, however, the experimental results 

 which, so far, appear to confirm my theory, it will be necessary to describe 

 the habits and peculiarities of this insect. 



Most books on natural history inform us that only the female mosqui- 

 to stings human beings and animals for the purpose of sucking their 

 blood, the males feeding only on sweet juices or nutrient liquid. The 

 fecundated females, in cold climates, hibernate during winter, in a state 

 of apparent death, in dark corners, in cellars, etc., to revive with the return 

 of warm weather, when they will lay eggs and propagate their species. I 

 was unable, however, to ascertain from previous writers whether gnats, in 

 general, suck blood more than once, how long they live after their first bite, 

 and many other particulars essential for my investigation. I was, therefore, 

 obliged to undertake a systematic study of the species generally found in 

 Havana, to which alone the following remarks must be understood to apply, 

 leaving future inquiries to determine whether the same may be true of 

 others that are known to exist in the interior of the island and in foreign 

 countries. 



Two species of mosquitoes are commonly observed in Havana. One, the 



1) The American Journal of the Medical Sciences, Oct. 1886. pp. 395-409. 



