﻿ETIOLOGY OF DENGUE FEVER. 121 



November 2 : Patient feeling well and the eruption has almost disappeared. 



November 5 : Keturned to duty. 



Remarks. — It will be observed that this patient did not contract dengue 

 through the mucous membrane of the mouth nor from mosquito bites. As re- 

 gards the latter experiment, we can not be sure that he was bitten more than 

 one or two times by mosquitoes. From the intravenous inoculation of dengue 

 blood he developed a very typical case of the disease as will be seen by referring 

 to the temperature chart. The incubation period in this case was longer than 

 in any of our previous cases, being four days and four hours. 



Experiment No. 6. 



Case 6, Chart 6. — J. E. S., private, Troop H, Eighth Cavalry. At time of 

 experiments this man was in good health, but had been exposed to dengue at 

 Fort McKinley. The following is a record of the experiments performed in this 

 case : 



September 22: Exposed last night to mosquitoes that bit Case 41 (Chart G) 

 on September 13. Says that none bit him during the night. 



September 23 : Exposed again last night to mosquitoes, and says he was bitten 

 once. Dengue did not result from this experiment.- 



October 7: Patient was exposed to mosquitoes that bit Case 44 (Chart E) the 

 night before. 



October 8 to 15: Patient feeling well, and states that he does not know - 

 whether he has been bitten. Dengue did not result from this experiment. 



October 25: Slept last night with mosquitoes that had bitten Case 60 (Chart 

 F), and was bitten at least twice. 



October 26 to 28 : Mosquitoes have disappeared and patient has not been 

 bitten again. Dengue did not result from this experiment. 



October 31: Slept with mosquitoes that had bitten Case 65 (Chart J) last 

 night. 



November 1 to 3 : Has been bitten several times by the mosquitoes. 



November 4 : Patient feeling well and mosquitoes have all disappeared. Dengue 

 did not result from this experiment. 



November 8: At 3 p. m. to-day the patient was inoculated intravenously with 

 20 minims of blood from Case 70 (Chart K) . The man from whom the blood was 

 taken had a typical attack of dengue fever, and the inoculation was made upon 

 the third day of the disease. 



November 10 to 14: Patient feeling well. 



November 15 : In the afternoon the patient had a slight chill, headache and 

 general pains in the muscles. 



November 16: Patient complains of severe headache, backache and pain in 

 the limbs. Has no appetite. 



November 17 to 20: During this time the patient presented the usual symp- 

 toms of dengue, which have already been indicated. 



Remarks. — The chief point of interest in this case is the long period of incuba- 

 tion, exceeding that of any experimental case that we have observed. Inoculation 

 was made at 3 p. m. on November 8, and the first symptoms appeared in the 

 afternoon of November 15, making the incubation period about seven days. It 

 should be remembered that this man had already passed through a severe 

 epidemic of dengue, and it is probable that he possessed a relative immunity to 

 the disease, although his clinical symptoms were typical and rather severe in 

 character. 



