YELLOW FEVER 289 



To check the spread of the disease it is necessary to 

 prevent mosquitoes biting patients, and as far as 

 possible to destroy the mosquitoes. In Havana, 

 the place chosen for the first campaign against the 

 disease, patients were confined in mosquito nets, 

 and the breeding places of the mosquito, large and 

 small collections of water, were removed or treated 

 in various ways. The result was that within a few 

 months the disease had ceased in Havana, a place 

 in which it had claimed very numerous victims 

 every year. 



"In the Panama Canal zone, which used to be 

 one of the worst endemic regions in Central America, 

 as a result of anti-mosquito campaigns the number 

 of cases of yellow fever was reduced so rapidly that 

 within five years the disease had completely dis- 

 appeared from this region." 



As evidence of the losses formerly caused by this 

 disease maybe cited the fact that "the French army 

 in Santo Domingo in 1798 out of a total strength 

 of 25,000 lost over 22,000 from yellow fever and four 

 years later out of a total of 40,000 it lost 20,000." 



We may next consider two very important 

 protozoal diseases, Malaria and Sleeping Sickness, 

 which are responsible for much sickness and an 

 enormous mortality annually. 



The parasites of Malaria, of which there are at 

 least three varieties, have two periods of multiplica- 

 tion in their life-cycles, one in the red blood 

 corpuscles of man and the other in a mosquito. 



S. S. N. 19 



