486 MAN CONTROLS HIS ENVIRONMENT FOR HEALTH 



is being successfully fought and conquered in Italy by the draining 

 of the mosquito-breeding marshes. 



The problem of malaria affects nearly 13,000,000 of the inhabit- 

 ants of the United States, principally those of the southern states. 

 Mississippi, with over 92 per cent of its population, shows a death 

 rate of over 10 deaths per 100,000 from malaria ; Florida with 80 

 per cent of her population exposed to malaria, and Arkansas, 

 with 75 per cent living in malarial districts, present the most 

 serious problems from a health standpoint. In Arkansas, Mis- 

 sissippi, and other southern states successful fighting of malaria 

 by draining marshes, oiling standing water, and screening houses 

 has greatly reduced the number of malarial patients. 



Project. To make a survey of your neighborhood to determine if 

 there are any breeding places for mosquitoes. How can these places 

 be reduced? 



Other protozoan diseases. Many other diseases of man are 

 probably caused by parasitic protozoans. Dysentery of one kind 

 is caused by the presence of an amoeba-like animal, Endamoeba, 

 in the digestive tract. These parasites are far more widely spread 

 than was ever thought and many people suffer from the effects of 

 this parasite without knowing what 'actually causes them to be ill. 



Another group of protozoan parasites are called trypanosomes. 

 These are parasitic in insects, fish, reptiles, birds, and mammals 

 in various parts of the world. They cause several diseases of 

 cattle and other domestic animals, being carried to the animal in 

 most cases by flies. One of this family is believed to live in the 

 blood of native African zebras and antelopes. Seemingly it does 

 them no harm, but if one of these parasites is transferred by the 

 dreaded tsetse (tse'tse) fly to one of the domesticated horses or 

 cattle of that region, the animal dies. 



The tsetse fly also carries to the natives of Central Africa a 

 trypanosome which causes the dreaded and incurable sleeping 

 sickness. This disease has killed more than fifty thousand 

 natives yearly, and many Europeans have succumbed to it. Its 

 ravages are largely confined to an area near the large Central Afri- 

 can lakes and the upper Nile, for the fly which carries the disease 



