TRANSMISSION OF YELLOW FEVER BY MOSQUITOES. 661 



that this insect was not a mosquito of the genus CalI&r, such as he had 

 used in his inoculation experiments. I also urged that efforts should 

 be made to ascertain definitely whether the disease can be connuuni- 

 cated from man to man by blood inoculations. Evidently, if this is 

 the case tiie blood must contain the living- infectious agent upon which 

 the propagation of the disease depends, notwithstanding the fact that 

 all attempts to demonstrate the presence of such a germ in the blood 

 by means of the microscope and culture methods had proved unavail- 

 ing. I had previously demonstrated \>^ repeated experiments that 

 inoculations of yellow-fever blood into lower animals — dogs, rabbits, 

 guinea pigs — give a negative result; but this negative result might 

 well be because these animals were not susceptible to the disease and 

 could not be accepted as showing that the germ of yellow fever was 

 not present in the blood. A single inoculation experiment on man 

 had been made in my presence in the city of Vera Cruz in 1887 by 

 Dr. Daniel Ruiz, who was in charge of the civil hospital in that cit3\ 

 But this experiment was inconclusive, for the reason that the patient 

 from whom the blood was obtained was in the eighth day of the 

 disease, and it was quite possible that the specific germ might have 

 been present at an earlier period and that after a certain number of 

 days the natural resources of the body are sufficient to effect its 

 destruction, or in some way to cause its disappearance from the 

 circulation. 



This was the status of the question of yellow-fever etiology when 

 Doctor Reed and his associates commenced their investigations in Cuba 

 during the summer of 1900. In a '^Preliminary note" read at the 

 meeting of the American Public Health Association, October 22, 1900, 

 the board gave a report of three cases of yellow fever which they 

 believed to be the direct result of mosquito inoculations. Two of 

 these were members of the board, viz: Dr. Jesse W. Lazear and Dr. 

 James Carroll, who voluntarily submitted themselves to the experi- 

 ment Doctor Carroll suffered a severe attack oi the disease and re- 

 covered but Doctor Lazear fell a victim to his enthusiasm in the cause 

 of scienc-e and humanitv-' His death occurred on September 25, after 

 an illness of six davs' duration. A})Out the same time nine other indi- 

 viduals who volunteered for the experiment were bitten b^-m tec-ted 

 mosquitoes-i. e., bv mosquitoes which had previously been allowed to 

 fill themselves with^blood from yellow-fever cases-and in these cases 

 the result was negative. In considering the experimental evidence 

 thus far obtained the attention of the members of the board was 

 attracted bv the fact that in the nine inoculations with a neg|itive 

 result -the time elapsing between the biting ot the mosquito and the 

 inoculation of the healthy subject varied in seven cases from two to 

 "ght days and in the remaining two from ten toHm-teen days whereas 

 in two of the three successful cases the mosquito had been kept for 



