﻿136 ASHBUKN AND CRAIG. 



throughout the day. It is noteworthy that the only men unprotected 

 by the mosquito nets at night — that is, the three night nurses — all 

 developed the disease. 



2. In our dengue hospital, where we treated over 120 cases, no in- 

 stance of infection occurred among the attendants, although their associa- 

 tion with the dengue patients was very intimate and continued for over 

 four months. 



3. Our experiments with fomites were all negative. We endeavored 

 to produce the disease by exposure of healthy men to fomites, the men 

 experimented with living in mosquito-proof tents with patients suf- 

 fering from dengue, throughout the entire course of the disease. They 

 slept in their beds, wore their underclothing and pajamas, and ate and 

 drank from the same table furniture. In this way we experimented with 

 eight men, none of whom developed the disease from such exposure. 



We conclude, therefore, that dengue is not a contagious disease, and 

 that patients suffering from it may be placed in the general wards of a 

 hospital without fear of infection, provided precautions are taken to 

 protect the patients from mosquitoes. 



Conclusions regarding the etiology of dengue. — From our study of the 

 etiology of dengue, we believe the following conclusions are justified : 



1. Xo organism, either bacterium or protozoon, can be demonstrated 

 in either fresh or stained specimens of dengue blood with the mi- 

 croscope. 



2. The red blood count in dengue is normal. 



3. There occur no characteristic morphological changes in the red oi 

 white blood corpuscles in this disease. 



4. Dengue is characterized by a well-marked leucopenia, the polymor- 

 phonuclear leucocytes being decreased, as a rule, while there is a marked 

 increase in the small lymphocytes. 



5. The intravenous inocidation of unfiltered dengue blood into healthy 

 men is followed by a typical attack of the disease. 



6. The intravenous inoculation of filtered dengue blood into healthy 

 men is followed by a typical attack of the disease. 



T. The cause of the disease is, therefore, jjrobably ultramicroscopic. 



8. Dengue can be transmitted by the mosquito, Culex fatigans Wied., 

 and this is in'obably the most common method of transmission. 



9. Xo organism of etiological significance occurred in bouillon or 

 citrated blood cultures. 



10. The period of incubation in experimental dengue averages three 

 days and fourteen hours. 



11. Certain individuals are absolutely immune to dengue., as proven 

 by our experiments. 



12. Dengue is not a contagious disease, but is infectious in the same 

 manner as is yellow fever and malaria. 



