Mosquitoes and Yellow Fever 123 



from the disease, but are usually regarded as prac- 

 tically immune. 



It was early observed, too, that the danger zone 

 might be quite well defined and that outside this 

 zone one would be safe. More than a century 

 ago the British troops and other inhabitants of Ja- 

 maica found that by retreating to the mountains 

 during the warm weather the non-immunes could 

 escape the fever. It was also observed that those 

 who slept on the first floor were more apt to take 

 the disease than those on the second floor. 



THE YELLOW FEVER COMMISSION 



In 1900, during the American occupation of 

 Cuba, yellow fever became very prevalent there. 

 A board of medical officers was ordered to meet in 

 Havana for the purpose of studying the disease 

 under the favorable opportunities thus afforded. 

 This board, which came to be known as the Yellow 

 Fever Commission, was composed of Drs. Walter 

 Reed, James Carroll, Jessie W. Lazear and Aristi- 

 des Agramonte of the United States Army. Agra- 

 monte was a Cuban and an immune, the others 

 were non-immunes. Dr. Manson in his lectures on 

 Tropical Medicines says of them: 



"I cannot pass on, however, to what I have to say 

 in connection with this work without a word of admira- 



