Mosquitoes and Yellow Fever 205 



volunteers presenting themselves, one of these mosquitoes died the 

 sixty-ninth and one the seventy-first day after their original con- 

 tamination, without it being determined whether they were still 

 capable of transmitting the disease. 



So carefully carried out was this work and so conclusive were the 

 results that Dr. Reed was justified in writing: 



"Six months ago, when we landed on this island, absolutely noth- 

 ing was known concerning the propagation and spread of yellow 

 fever it was all an unfathomable mystery but today the curtain 

 has been drawn its mode of propagation is established and we know 

 that a case minus mosquitoes is no more dangerous than one of 

 chills and fever." 



The conclusions of the Commission were fully substantiated by 

 numerous workers, notably Dr. Guiteras of the Havana Board of 

 Health, who had taken a lively interest in the work and whose 

 results were made known in 1901, and by the Brazilian and French 

 Commission at Sao Paulo, Brazil, in 1903. 



Throughout the work of the Army Commission and down to the 

 present time many fruitless efforts have been made to discover the 

 specific organism of yellow fever. It was clearly established that 

 the claims of Sanarelli for Bacillus icteroides were without founda- 

 tion. It was found, too, that whatever the infective agent might 

 be it was capable of passing through a Berkefeld filter and thus be- 

 longs to the puzzling group of "filterable viruses." It was further 

 found that the virus was destroyed by heating up to 55 C for ten 

 minutes. It is generally believed that the organism is a Protozoan. 



The question of the hereditary transmission of the yellow fever 

 organism within the mosquito was left unsettled by the Army Com- 

 mission, though, as we have seen, it was raised by Finlay. Marchoux 

 and Simond, of the French Commission devoted much attention to 

 this phase of the problem and basing their conclusions on one ap- 

 parently positive case, they decided that the disease could be trans- 

 mitted through the egg- of an infected Aedes calopus to the second 

 generation and thence to man. The conclusion, which is of very 

 great importance in the control of yellow fever, has not been verified 

 by other workers. 



Once clearly established that yellow fever was transmitted solely 

 by mosquitoes, the question of the characteristics, habits, and geo- 

 graphical distribution of the insect carrier became of vital import- 

 ance. 



