CHAPTER IX. 

 YELLOW FEVER. 



THE parasitology of this disease is unknown. It is 

 in no way connected with malaria, but as it has been 

 proved to be carried by a mosquito, Stegomyia fasciata 

 (S. calopiis), and as there is further proof that time has 

 to elapse after the infection of the mosquito before it 

 in turn becomes infective, development must take place 

 in the mosquito. On these grounds the disease is here 

 included with the probably protozoal diseases. 



Yellow Fever in its severer form is characterized by 

 fever, intense headache, jaundice, and albuminuria in- 

 creasing steadily in amount ; by tendency to haemor- 

 rhages from mucous and sometimes from cutaneous 

 surfaces, and by haematemesis "black vomit." In fatal 

 cases there is frequently suppression of the urine. In the 

 milder form there is fever for two or three days, gastric 

 disturbance, and epigastric pain. 



It is conveyed from man to man by mosquitoes 

 belonging to the genus Stegomyia. 



Geographical Distribution. It is best known as a disease 

 of the New World, and occurs endemically, or as epidemics, 

 in the West Indies and along the Atlantic coast from 

 New York down to Rio de Janeiro. It was at one time 

 common in the West Coast of Africa, and recent out- 

 breaks have occurred. In South Europe, on the Atlantic 

 coast, it is an imported disease, and on board ship. It 

 has spread to a small extent even in English ports in 

 the vicinity of infected ships, during summer months. 



It is usually limited to the larger settlements on the 

 coast in the Tropics. Ship epidemics were common in 

 the past, but are now rare. 



