PROTOZOA 9 



In 1900, during the American occupation of Cuba, the yellow fever 

 became so prevalent there that a yellow fever commission of medical 

 officers was ordered to study the disease. Dr. Finlay of Havana 

 had claimed that the disease was transmitted by the bite of a mosquito, 

 and the commission decided to prove or disprove this theory. No 

 braver nor more useful piece of work has, perhaps, ever been done 

 than that of the members of this commission Drs. Reed, Carroll, 

 Lazear and Agramonte. The crucial test was to let an infected 

 mosquito that is, one that had bitten a yellow fever patient bite 

 a non-immune person to see if the disease would thus be transmitted. 

 Dr. Carroll allowed himself to be bitten by such a mosquito and in due 

 time developed the disease, so that he was the first person to whom 

 it was proven that the mosquito had carried the disease. His heroism 

 fortunately did not cost him his life, but Dr. Lazear, who was accident- 

 ally bitten, died in a few days. Other volunteers allowed themselves 

 to be experimented upon, and, when the conditions were right, developed 

 the disease. It was found that it is only during the first three days 

 of the disease that a mosquito may be infected by biting a yellow 

 fever patient, and that 12 days must elapse before this mosquito is 

 capable of infecting another person. It is even claimed that the 

 mosquito may transmit the infecting power to her offspring. Various 

 experiments like the one quoted above for malaria were tried with 

 yellow fever. For example, a number of non-immunes lived for three 

 weeks in a mosquito-proof house, where they were supplied with 

 clothing and other articles from a yellow fever hospital. They even 

 slept between soiled sheets from a bed which a yellow fever patient 

 had occupied. None of them developed the disease. When some of 

 these men were later inoculated they developed the disease, showing 

 that they were not immunes. 



Thus it was conclusively proven that yellow fever is transmitted 

 by the bite of the Stegomyia mosquito and in that way alone. The 

 effect of this discovery upon the health of Havana,, New Orleans, the 

 Canal Zone and other pest-ridden places, is known to all. The problem 

 resolved itself simply into cleaning up the swamps, covering the cisterns, 

 etc., thus exterminating the mosquitoes. The methods employed in 

 this work will be discussed in the section dealing with insects. 



The terrible mortality among the laborers, engineers, doctors and 

 nurses, while the French were at work upon the Panama Canal, was 



