﻿ETIOLOGY OP DENGUE FEVER. 95 



Foster says that most of them have considered it a modified yellow fever. We 

 do not so infer from such literature as we have seen. They speak of it as 

 having a common cause, but as these statements were made before the specific 

 causes of any of the fevers were known, we take it that the writers meant merely 

 that the cause of both was a "miasm," an atmospheric condition, the state of the 

 ground water, etc. We have not found any author who states that the one 

 disease may arise from the other. 



The disease has occurred in most widespread epidemics in the tropical and 

 subtropical world, not only covering large areas of country, but attacking a 

 greater proportion of the inhabitants than probably any other known disease, and 

 usually also affecting most of the other members of a family after one has been 

 attacked. That being the case, it is rather surprising that a belief in its 

 contagiousness has not been practically universal. 



As a matter of fact, only a minority of the authorities whose writings are 

 accessible to us have expressed an unqualified belief in its contagiousness, while 

 many have rejected it entirely. 



Dickson considered it very highly contagious, while many of his contemporaries 

 liken it to yellow fever in its manner of progression. Most writers express them- 

 selves as in doubt on the subject. Wragg denied contagiousness, as did Horlbeck 

 (4). 



Holliday (6) wrote to sixty practitioners who had large experience with the 

 disease, asking their opinions as to its contagiousness. Forty-five replied that 

 it was simply epidemic, four that it was contagious, two were in doubt, and the 

 rest did not answer. 



One point on which the writers, from first to last, almost unanimously agree 

 .is the influence of atmospheric conditions. Hot, sultry weather, with abundant 

 rains, is by all thought to favor the occurrence of epidemics. Nearly all also agree 

 in stating that lowlands, seaports, the deltas of rivers and the neighborhood of 

 marshes, are favorable places for the occurrence of the disease, while it seldom 

 prevails extensively inland, and almost never at high altitudes. 



If, in addition to this, we consider that it is a tropical disease, only extending 

 as far north as our Gulf States and Charleston in the summer, usually about 

 August, and dying out with the coming of frost (6), we have one of the reasons 

 for likening it to yellow fever. Epidemics have possibly occurred in Philadelphia 

 in 1780, and Ohio, in 1828, though we have not had access to the original accounts 

 of these outbreaks, but it was only in the hottest part of the year in each instance. 



Guiteras and Cartaya (7) say: "Dengue presents in its epidemiology a great 

 resemblance to mosquito-borne disease, especially yellow fever. Epidemics appear 

 in the hot season, even in the Tropics. It selects by preference the great seaports, 

 the coast, and avoids the interior highlands. We meet places in which infection 

 persists, epidemics which develop slowly in the beginning. If it then spreads 

 rapidly it is because of the shortness of the incubation and the presence of many 

 susceptible people. * * * Everything indicates that its transmission is not 

 direct from sick to well. * * * It is common for a sick person to be taken to 

 a place where dengue does not exist, and no harm result. * * * In Havana 

 itself, and at the very height of the epidemic, there was a place in which the disease 

 did not spread, simply because of freedom from insects. In Las Animas (Hos- 

 pital) we have treated a good number of cases in the same rooms with other 

 patients * * * without any contracting dengue. We have treated the greater 

 part of our eases in the pavilion used for infectious diseases of known means of 

 transmission, a pavilion protected against insects by metallic screening and 

 frequent fumigation to kill mosquitoes, but where other disinfection was not 

 practiced, and still dengue has not been transmitted to anyone." 



