﻿ETIOLOGY OP DENGUE FEVER. 119 



creased, covering the entire body, being especially marked, over the trunk and 

 limbs. 



August 25: Patient slept well and all symptoms have disappeared except 

 slight headache and pain in the eyes. The eruption is fading and the itching 

 is very annoying; there is considerable desquamation present in the form of 

 small white scales. 



August 27 : Eruption has disappeared. Patient feels well. 



August 3 1 : Returned to duty. 



Remarks. — The incubation period in this case was about two days and eighteen 

 hours. The temperature curve is not as characteristic as is generally observed, 

 but the symptoms were very typical, and the fact that we were able to produce 

 a very severe case of dengue by the injection of the filtered blood of this patient 

 proves beyond doubt the nature of the disease ( see Case 9, Chart 9 ) . An 

 interesting feature of this case is the early appearance of a well-marked erup- 

 tion, which, after fading gradually, increased again during the crisis and finally 

 disappeared, accompanied by considerable desquamation. It is also interesting 

 to note that in the case of dengue referred to as being produced by the inocula- 

 tion of filtered blood from this case, the eruption appeared early and presented 

 the same characteristics. While the temperature was low the symptoms were 

 more severe than in many others in which the fever was much greater, and the 

 eruption was almost as well marked as in any case that we have observed. 



In the three cases just described the inoculations were made as soon as the 

 subject volunteered, no previous experiment in the way of exposure to fomites or 

 mosquitoes having been tried. In the case which follows, the inoculations were 

 used as a final test of immunity, the men inoculated having been exposed to both 

 fomites and infected mosquitoes. 



Experiment No. 4. 



Case 4> Chart 4- — C. H. B., private, Troop A, Eighth Cavalry. Had been 

 exposed to dengue, his troop having had eighteen men on sick report with the 

 disease. At time of volunteering he was in good health, and stated that he had 

 never had any serious illness. The following is a brief resume of the clinical 

 record in this case: 



September 22 : Exposed to fomites of dengue, being placed with three dengue 

 cases in a mosquito-proof tent, sleeping in their beds and wearing their under- 

 clothes. 



September 26: No result being obtained from fomites after four days, the 

 patient is to sleep to-night under net with about forty mosquitoes which bit 

 Case 38, who had a typical case of dengue (see Chart D) on the night of 

 September 25. 



September 27 : Feels well. Says he was not bitten by a single mosquito. 



September 28: Feels well. Says that he has not yet been bitten by the 

 mosquitoes. 



September 28 to October 2: During this time the patient has slept under the 

 net containing the infected mosquitoes, but claims that he has not been bitten 

 at all, and his statement is confirmed by the fact that the mosquitoes all 

 remained empty during this time, and made no attempt to bite, most of them 

 dying while within the mosquito net. He states that so far as he knows he has 

 never been bitten by a mosquito, although he had campaigned in localities in Africa 

 which were almost uninhabitable because of these insects. At first we were 

 inclined to doubt his statements in this respect, but observation has convinced 

 us that this man is really immune to mosquitoes. 

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