﻿ETIOLOGY OF DENGUE FEVER. 135 



Case 13. — J. G., private, Company I. Sixteenth Infantry. This soldier belonged 

 to a company of the Sixteenth Infantry that had furnished twelve cases to the 

 hospital with dengue before this man volunteered. He had therefore been 

 exposed to the disease. 



Experiment 1 : On September 12, 1906, the subject rinsed his mouth with 

 normal salt solution containing 12 minims of dengue blood, our object being to 

 determine if the dengue parasite could infect through an intact mucous mem- 

 brance. The result of the experiment was negative. 



Experiment 2: On September 19 the subject was given an intravenous inocula- 

 tion of filtered blood from Case 11 (Chart 11). No symptoms developed. 



Experiment 3 : On the night of October 4 the subject was exposed to mosquitoes 

 that had bitten Case 44 (Chart E) the night before, and was bitten at least twice. 

 Dengue did not develop. » 



Experiment 4: On the night of October 15 he was bitten many times by 

 mosquitoes that had bitten a dengue case two nights before. The result was 

 negative. 



Experiment 5: On October 22 the subject was given an intravenous inoculation 

 of 20 minims of unfiltered blood from Case 95 (Chart S). No symptoms of 

 dengue developed, and the man was returned to duty October 29, 190G. 



Case l.'i. — J. B. P., private, Company M, Sixteenth Infantry. At the time 

 of volunteering the company to which this man belonged had furnished ten men 

 suffering from dengue to the Forth McKinley Hospital. 



Experiment 1 : On the night of September 24, 1906, the subject was exposed 

 to mosquitoes that had bitten Case 11 (Chart 11) the night before. He was 

 bitten several times and also many times during the next ten days. The result 

 of the experiment was negative. 



Experiment 2: The subject was exposed October 26 and 27 to mosquitoes that 

 had bitten a typical case of dengue on October 25. The result of the experiment 

 was negative. 



Experiment 3 : On November 17 the subject was given an intravenous inocula- 

 tion of unfiltered blood from Case 82 (Chart N), who was suffering from a 

 typical attack of dengue. No successful result was obtained in this experiment, 

 and the man was returned to duty November 23, 1906. 



Remarks. — 'These men were all exposed to fomites, in addition to the experi- 

 ments outlined, and we believe that the results of these experiments demonstrate 

 that absolute immunity to dengue is present in certain individuals. 



9. CONTAGION IN DENGUE. 



We have already noted the theories regarding the contagious character 

 of dengue. We have carefully studied this portion of our subject, and 

 believe that the following facts conclusively prove that dengue is not 

 contagious in the least degree. 



1. At the hospital at Fort William McKinley over 600 cases of dengue 

 were treated in the general wards without a single case originating 

 among the other patients in the wards. Only four men belonging to the 

 Hospital Corps on duty at this hospital contracted the disease, three of 

 them being nurses on night duty in the wards and the other a cook 

 having no contact with the dengue patients. No precautions were used 

 to prevent contagion other than the rigid use of mosquito nets at night, 

 the dengue and other patients eating together, and being closely associated 



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