CHAPTER L 



YELLOW FEVER 



Yellow fever is an acute infectious disease which prevails endemi- 

 cally in the tropical countries of the Western Hemisphere, but occurs also 

 along the western coast of Africa and has exceptionally appeared, in 

 epidemic invasions, in the north temperate United States and Europe. 

 Guiteras, as quoted by Osier, classifies the distribution of the disease into 

 three areas of infection. 



1. The area in which the disease is never absent, including tropical 

 South American ports and Havana. 



2. The area of periodic epidemics, including sea-ports of the tropical 

 Atlantic in America and Africa. 



3. The area of accidental epidemics, extending from parallel 45° 

 north latitude to 35° south latitude. In the United States severe epi- 

 demics have frequently occurred in Louisiana, Mississippi, and Alabama, 

 and occasional but severe epidemics have occurred in Philadelphia and 

 Baltimore. 



The disease occurs spontaneously only in man, and experimental 

 inoculation of lower animals has been successful only in the chimpanzee 

 in a single case reported by Thomas.' 



In man afflicted with the malady the clinical picture is one of a rapidly 

 developing fever with severe gastrointestinal symptoms, vomiting of 

 blood, albuminuria, and often active delirium. The mortality is usually 

 high, often reaching eighty per cent or more in the severe epidemics. 



Etiology and Method of Transmission. — The actual infective agent 

 which causes yeUow fever is, as yet, unknown. Numerous researches 

 have been aimed at the elucidation of the problem, and microorganisms, 

 for which etiological significance was claimed, have been isolated from 

 the dejecta, the vomitus, and the secretions of afflicted patients. None 

 of these claims has been supported by convincing proof and none of 

 them has found subsequent confirmation. 



A few of these claims only have historical importance because of the 



1 Thomas, Brit. Med. Jour., 1, 1907. 

 668 



