

Three of these oval red blood cells contain a common 

 sporozoan parasite of birds, Haemoproteus, here made 

 more visible by use of a dye. The parasite is trans- 

 ferred from one bird host to another by a blood-suck- 

 ing fly, in whose body the parasite goes through a 

 sexual part of its life history. (General Biological Sup- 

 ply House, Chicago. ) 



edge, which was not finally established until 1898, 

 the course of human culture was long deeply influ- 

 enced by the sporozoan that we now call Plasmo- 

 dium. No human tyrants, nor all the wars in human 

 history, have taken the toll of misery and death ex- 

 acted by the malarial parasite in those warm or tem- 

 perate parts of the world where anopheline mosqui- 

 toes are infected with Plasmodium. Malaria was well 

 known to the Greeks twenty-five hundred years ago, 



but perhaps it was introduced, after they had already 

 achieved their fine civilization, by soldiers returning 

 from military triumphs or by slaves brought in to do 

 their menial work. Whether malaria came to the New 

 World with the Spaniards or was already here when 

 they came, it was one of the major hazards, less men- 

 tioned but probably more important than either hun- 

 ger or Indian attacks. Malaria may have been the 

 disease that in 1607 killed half the settlers at James- 

 town, and malaria epidemics are recorded for Mas- 

 sachusetts as early as 1647. It was one of the chief 

 burdens of the pioneers who moved westward into 

 the Mississippi Valley, and as late as the I930's was 

 still widespread in the southern part of that valley. 

 If the history of man had not in the past been written 

 to so great an extent by militarily and politically 

 minded writers, it might tell a very different sort of 

 story. The southern part of the United States has lost 

 much of its strength to a disease that annually, until 

 World War 11, debilitated at least a million Ameri- 

 cans and killed several thousand. During the war, 

 when quinine ran out among the men at Bataan, 85 

 per cent of every regiment developed acute malaria. 

 And in the South Pacific campaign there were five 

 times as many casualties from malaria as from com- 

 bat. Up to the end of the war there were in all the 

 world some 350,000,000 cases of malaria annually, 

 of which about 3,500,000 resulted in death each 

 year. 



Since that time a dramatic change has come. New 

 therapeutic drugs, spraying of houses with DDT, bet- 

 ter control of mosquito breeding places, and better 

 organized health care have wiped out malaria in the 

 United States and brought it completely under con- 

 trol in parts of Europe, especially Italy, where it was 

 so long a heavy drain on the life of the people. A vast 

 improvement has been made in a great many parts of 

 Africa and of Asia. But to assume that man has 

 necessarily consigned malaria to his unhappy past is 

 naive. Our control of malaria depends upon the 

 proper functioning of a complex civilization that can 

 break down as others have in the past, while the 

 biological potential of mosquitoes and sporozoans is 

 built firmly into the species. Long before there were 

 men about, hemosporidians were living in lizards, 

 birds, bats, small rodents, monkeys, apes, and others. 

 Much of what we know about human malaria was 

 first learned from studies in birds, whose malaria is 

 transmitted by mosquitoes of the common genus 

 Cule.x and certain related genera. There are four 

 species of Plasmodium that cause malaria in man. 

 P. ovale is rare but found in many separated parts 

 of the world. P. vivax, P. malariae, and P. falciparum 

 are common and widespread, and each causes a 

 distinctive set of cyclic symptoms corresponding to 

 forty-eight-hour, seventy-two-hour, and forty-hour 

 cycles of development respectively. 



50] 



