YELLOW FEVER 



These very mild cases may form the greater number in 



o found the 



an outbreak, and unless severe cases are 



epidemic may be overlooked. The mild /b^sfeS by them- 



selves are very difficult to diagnose, but they are of special 



importance as they are the " reservoirs " of the c 



and from them the mosquitoes derive their infection an< 



may spread it either in the mild or severe 



mild cases are believed by some to be the 



coloured persons and in young children, and irffiese 



there may be no single symptom diagnostic of the 



disease. 



FIG. 34. 



In other cases, after a short apyrexial period or period 

 with a moderate temperature, the temperature again rises 

 (fig. 35) secondary fever but the pulse-rate remains 

 low, the vomiting recurs, and the vomit if not previously 

 mixed with blood is so now (yellow fever gravior). The 

 urine becomes more and more loaded with albumin, and 

 diminished in amount, and the distressing symptoms 

 again recur. This is the most dangerous stage and 

 may last for about a week or more. In cases pro- 

 gressing favourably the symptoms gradually subside, the 

 temperature gradually falls and the amount of urine 



