1236 



YELLOW FEVER 



The Vomit. — ^The vomit is often distinguished as white, red, and 

 black. The white is acid, colourless or bile-stained, and is composed 

 largely of mucus. The red vomit contains bright blood, while the black 

 is acid, containing hydrochloric acid, epithelial cells, red corpuscles, 

 fat, debris, and micro-organisms, its colour being due to the presence 

 of haemoglobin, turned to acid hsematin by the hydrochloric acid. 



Morbid Anatomy. — ^The skin is yellow from bile-pigment, and 

 blotched with post-mortem lividity and haemorrhages. The mucosa 

 of the tongue is fissured, and the mouth may be covered with blood. 

 The liver is yellowish or brownish in colour, marked by haemorrhages. 

 The cells are swollen and in a state of advanced fatty degeneration. 

 The gall-bladder contains inspissated bile, sometimes mixed with 

 blood. The spleen is normal in size, but may be congested and soft. 

 The stomach and intestines may be full of blood, usually in the form 

 of a black homogeneous tarry fluid containing black particles, and the 

 mucosa of the stomach, especially that of the pylorus and duodenum, 

 is usually much swollen, and the mesenteric glands may sometimes 

 be enlarged. The kidneys are, as a rule, normal in size, and show 

 signs of some congestion. Bowman's capsules are said to be dilated, 

 but this is not constant. The cells of the tubules show fatty de- 

 generation, and the lumen may contain granular debris. The supra- 

 renal capsules may be hypersemic or show fatty degeneration, but 

 neither of these is constant, and hyperaemia or fatty degeneration 

 of the pituitary body and the thyroid gland have been described, 

 but are not important. The bladder is usually empty. The heart 

 shows ecchymoses, and effusions may be found in the pericardium. 

 The lungs may be congested, and haemorrhages may be found beneath 

 the pleura. The uterine mucosa is congested, and there may be 

 blood in the cavity. The meninges of the brain are congested, and 

 haemorrhagic spots may be seen. 



Symptomatology — Incubation.— An exact knowledge of the length 

 of the incubation period is of the utmost importance from a pro- 

 phylactic point of view. Calculated from experimental mosquito 

 bites, it varies from two days twenty-two hours to seven days five 

 hours, but the latter figure was in a man who had had a mild attack. 

 With regard to the former period, it is the shortest actual record, 

 but some more doubtful figures, as low as two days one hour, are 

 given. Excluding the man with the slight attack, the incubation 

 period, as generally given by American observers, would be from 

 two days twenty-two hours to six days two hours. Marchoux, 

 Salimbeni, and Simond consider that the incubation may be as long 

 as twelve days, and draw this conclusion from inoculation of modified 

 blood serum, and also from natural infection. Carter's careful 

 clinical records, however, give the incubation period as varying from 

 three to five and three-quarter days. 



The average time appears to be about five days, but to be on the 

 safe side at least six to seven days must be allowed. 



The Fever. — ^The fever is divisible into two paroxysms, separated 

 by a remission or intermission, The first attack is characterized 



