THE YELLOW-FEVER MOSQUITO 103 



to time the disease has been carried to neigh- 

 bouring parts of America, especially to the 

 Gulf, Central America, and the northern coast 

 of South America. It has been introduced 

 more than once into Monte Video and Buenos 

 Ayres, and has even penetrated up the Parana 

 as far as Asun9ion. Every few years it ex- 

 tends into the Southern States and has even 

 reached Philadelphia and Boston. With the 

 exception of an outbreak in Leghorn in 1804, 

 European epidemics have been confined to 

 Portugal, Spain, and the Balearic Islands. 



It will have been noticed that most of these 

 outbreaks occur on the coast and then pass 

 up the rivers. It is thus most probable 

 that the disease is one which is brought mainly 

 by ships. It is obviously a disease which 

 must be guarded against by our troops fighting 

 near the coast in West Africa, as well as such 

 troops as are left in the West Indies. But, above 

 all, it must be guarded against in relation to 

 our shipping fleet and our Navy, operating off 

 the South American coasts. The danger, 

 now the Panama Canal is open, of introducing 

 the disease from America to Asia is a danger 

 that should carefully be considered. 



Yellow fever is a disease which requires a 

 winter temperature of at least 68° F., for it is a 

 mosquito-borne disease, and the yellow-fever 

 mosquito flourishes best at about this tempera- 



