202 Arthropods as Hosts of Pathogenic Protozoa 



include the important circumstance that the faculty of transmitting 

 the yellow fever germ need not be limited to the parent insect, 

 directly contaminated by stinging a yellow fever patient (or per- 

 haps by contact with or feeding from his discharges), but may be 

 likewise inherited by the next generation of mosquitoes issued from 

 the contaminated parent." He believed that the bite of a single 

 mosquito produced a light attack of the disease and was thus effec- 

 tive in immunizing the patient. Throughout the period, many 

 apparently successful attempts to transmit the disease by mosqui- 

 toes were made. In the light of present day knowledge we must 

 regard these as defective not only because possibility of other infec- 

 tion was not absolutely excluded but because no account was taken 

 of the incubation period within the body of the mosquito. 



In 1900, while the American army was stationed in Cuba there 

 occurred an epidemic of yellow fever and an army medical board was 

 appointed for "the purpose of pursuing scientific investigations with 

 reference to the acute infectious diseases prevalent on the island." 

 This was headed by Walter Reed and associated with him were James 

 Carroll, Jesse W. Lazear and Aristides Agramonte, the latter a Cuban 

 immune. For a detailed summary of this work the lay reader can- 

 not do better than read Dr. Kelly's fascinating biography ''Walter 

 Reed and Yellow Fever." 



Arriving at the army barracks near Havana the Commission first 

 took up the study of Bacillus ictermdes, the organism which Sanarelli, 

 an Italian physician, had declared the causative agent in yellow fever. 

 They were unable to isolate this bacillus either from the blood during 

 life or from the blood and organs of cadavers and therefore turned 

 their attention to Finlay's theory of the propagation of yellow fever 

 by means of the mosquito. In this work they had the unselfish 

 and enthusiastic support of Dr. Finlay himself, who not only consulted 

 with them and placed his publications at their disposal, but furnished 

 eggs from which their experimental mosquitoes were obtained. 

 Inoculations of eleven non-immunes through the bite of infected 

 mosquitoes were made, and of these, two gave positive results. The 

 first of the two was Dr. Carroll who allowed himself to be bitten 

 by a mosquito which had been caused to feed upon four cases of 

 yellow fever, two of them severe and two mild. The first patient 

 had been bitten twelve days before. 



Three days after being bitten, Dr. Carroll came down with a 

 typical case of yellow fever. So severe was the attack that for three 



