44 INSECTS AND DISEASE 



work has been carefully done the death rate from malaria has been re- 

 duced to a small fraction of that formerly prevailing. 



Other Diseases Transmitted 



Yellow fever is transmitted solely by certain species of mosquitoes. 

 In Montana and Idaho a disease known as spotted fever is carried 

 by a tick. The terribly fatal bubonic plague is transmitted largely by 

 fleas. A species of fly has been found to be the means of spread of the 

 sleeping sickness that has been ravaging some sections of Africa. Yet 

 this is only a part of the known list. 



Among domestic animals, a striking example is found in the disease 

 known as Texas fever, which has caused tremendous losses among 

 owners of cattle. The organism causing this disease is carried by a 

 species of tick, and infection invariably takes place only through the 

 bite of this tick. In Asia and Africa other serious or fatal diseases 

 of domestic animals have been traced to insect carriers, and it is 

 probable that similar discoveries will be made here. 



