﻿114 ASHBURX AND CRAIG. 



2. Dengue is not accompanied by anaemia, the red blood count being 

 normal in uncomplicated eases. There are no characteristic morpholo- 

 gical changes in the red corpuscles, leucocytes, blood plates or blood 

 plasma. 



3. Dengue is characterized by a leucopenia and in the vast majority 

 of instances by a decrease in the polymorphonuclear leucocytes and a 

 marked increase in the small lymphocytes; the increase in the small 

 lymphocytes is constant throughout the disease. 



(d) Blood plates. — We have observed no changes in the number or 

 appearance of the blood plates in dengue. 



(e) 27/ e Wood plasma. — In neither fresh nor stained specimens of 

 blood *have we been able to demonstrate any organism of etiological 

 significance in the blood plasma in dengue. In a few instances bacteria 

 were noticed but from the ease with which blood cultures collected 

 with the most careful attention and asepsis become contaminated in this 

 climate, we believe that these bacteria were of external origin. The 

 most common bacterium observed was a long, stout bacillus, actively 

 motile, and commonly seen here in blood specimens from various 

 sources. No organism resembling a protozoon was observed in the 

 blood plasma. Yeast cells were frequent contaminations in stained 

 specimens. 



3. BLOOD CULTURES. 



With the exception of McLaughlin's researches, which have been men- 

 tioned and which, so far as cultural methods are concerned, were almost 

 valueless, Ave have not been able to find in the literature an)^ detailed 

 descriptions of experiments having for their object the cultivation of 

 bacteria or protozoa from the blood of dengue patients. We therefore 

 approached this portion of our task with high hopes that by applying 

 modern cultural methods we might be able to isolate and cultivate the 

 organism causing the disease. In view of the success attained hy Novy 

 and others in the cultivation of tiypanosornes, and by Kodgers in cul- 

 tivating the Leishman-Donovan body (Herpetomonas donovani), we 

 were especially hopeful that by applying similar methods in this disease, 

 we might be able to secure growths of any protozoon which might be 

 present. As we have stated, we were impressed with the idea that 

 dengue might be caused by an organism belonging to the same group as 

 those producing relapsing fever, or to some closely allied group, and we 

 therefore endeavored, both by employing special staining methods and 

 culture media, to demonstrate such an organism. 



(a) Methods. — In our experiments we have used citrated blood and 

 acid and alkaline bouillon as culture media. In making cultures with 

 citrated blood, the sterilized syringe was first filled with citrated solu- 



