﻿130 ASHBURN AND CRAIG. 



invariably all the mosquitoes left alive had bitten and were full of 

 blood. The subject to be experimented upon, having been placed in 

 bed beneath a mosquito net in another mosquito-proof tent, the mos- 

 quitoes which had bitten the dengue case the night before were liberated 

 beneath his mosquito net, and orders given that the man remain beneath 

 the net until the mosquitoes had disappeared; later we allowed the men 

 to remain out of bed during the day, the mosquitoes being kept beneath 

 the spread net. With one exception, which has been noted, all the men 

 were bitten a few times, but in most instances the mosquitoes died before 

 the men had been bitten severely. We also confined mosquitoes that 

 had bitten dengue cases in glass jars, and kept them as long as from 

 four to six days before allowing them to bite, but in the few instances in 

 which we tried this method our results were all negative. 



We do not consider it necessary to give our negative results in full, 

 as they are all referred to in detailed experiments, and we will only 

 describe the case in which we produced dengue by allowing the volunteer 

 to be bitten by infected mosquitoes. 



Experiment No. 11. 



Case 11, Chart 11. — B. L. W., private, Hospital Corps, United States Army. 

 This man had been on duty at the Division Hospital for several weeks, and as no 

 eases of dengue had occurred in the hospital, had not been exposed to the disease, 

 so far as we could determine. On September 12, 1906, the man being in good health, 

 he was placed under a mosquito net with mosquitoes that had bitten Case 88 

 (Chart R) on the night of September 11. Case 88 was suffering at the time from 

 a typical attack of dengue. Case 11 was not bitten by mosquitoes until the 

 night of September 13, and developed no symptoms until the night of the 17th, 

 but upon reference to his chart it will be seen that he had fever for nearly twenty- 

 four hours before he noticed any symptoms. If we assume the period of incuba- 

 tion to be the period intervening between the 13th, the night upon which he was 

 first bitten, and the 16th, when he had his first rise in temperature, the incubation 

 period would be about three days and one-half. However, if we assume the 

 disease to have commenced when he first noticed symptoms — that is, upon the 

 evening of the 17th — the incubation period would be a little over four days. The 

 following is a summary of his clinical history: • 



September 12 : Put under net with mosquitoes that bit Case 88 last night. 



September 13: Bitten by mosquitoes last night. 



September 18: Had headache and felt uncomfortable last evening. This 

 morning complains of headache and a dull pain in the articulations. 



September 19 : Still complains of headache and general muscular pain and 

 soreness. His face and eyes are greatly congested. 



September 20: Last night had severe pain in the head, eyes and the muscles 

 of the back, but feels much better this morning. 



September 21 : Is feeling better. A faint rash is visible covering the chest 

 and abdomen. 



September 22 : Complains of soreness and stiffness in the muscles. The erup- 

 tion is now plainly visible and typical of dengue. 



September 24: Feels well. The eruption has almost disappeared. 



October 1 : Returned to duty. 



