28 DDT — Killer of Killers 



in its spread. A severe epidemic broke out in Vienna in 

 1916, spread over Europe, reached Great Britain, hopped the 

 ocean to North America, and appeared in about half of the 

 states of the U. S. A. by May, 1920. Australia had epidemics 

 in I917-I9I8 and again in 1922 and 1926. In the summer 

 of 1934, 60% of the over 7,000 viaims in Japan died, and 

 another epidemic broke out in Japan in the following year. 

 The United States had a widespread epidemic in 1933, and 

 has had a number of localized epidemics since. And the 

 disease is not limited to man, for horses and sheep are also 

 susceptible. 



For many years, the mosquito has been suspected of be- 

 ing the transmitting agent, and this ^as recently proved by 

 Doctors W. H. Hammon and W. C. Reeves of the Hooper 

 Foundation for Medical Research, University of California. 

 Of the many thousands of different kinds of insects that these 

 men and their co-workers collected, only the mosquito was 

 found guilty of carrying the virus. And even more startling 

 was the proof that birds, both wild and domesticated, are the 

 reservoirs of the disease. That is why most cases of en- 

 cephalitis occur in rural areas, small towns, and suburbs of 

 large cities — ^places where people keep chickens. 



We could go on and on and show the possible animal- 

 insea-man relationship in the transmission of many other 

 diseases, but we shall bring this section to a close with a few 

 words about African sleeping sickness. This disease is car- 

 ried by the tsetse fly, and it affeas animals as well as man. 

 The only way to control the spread of the disease is to elimi- 

 nate the flies, or at least to confine them to areas far from 

 human habitation. That is why a news item from Pretoria, 

 South Africa, dated July 21, 1946, is of particular interest. 

 Briefly, this article stated that the biggest wild animal hunt in 



