598 Malaria 



brought under control in others. At the opposite extreme, there are still 

 areas in which perhaps 90 per cent of the population have malarial 

 infections every year. The history of malaria in North America (11, 44, 

 119) illustrates the results which may be expected from more or less 

 systematic efforts to control the disease. 



The origin of malaria in North America is uncertain. Some authorities 

 suspect that the disease did not exist in the Am.ericas before their dis- 

 covery by Europeans. Others think that malaria was already endemic 

 when Europeans first reached America. At any rate, malaria has played 

 an important part in the history of North America for more than four 

 centuries. Introduction of slaves from Guinea into the West Indies was 

 begun about 1518 and the subsequently developed slave trade did much 

 to spread malaria, especially malignant tertian. 



The early Spanish and French expeditions to the Gulf and south 

 Atlantic coasts probably brought malaria to North America, but some 

 time elapsed before the disease became important here. The settlers w^ho 

 reached Roanoke Island in 1585 apparently were not troubled by malaria. 

 However, those who came to Jamestown in 1607 had been recruited 

 mostly from the London area where malaria was then endemic. Within 

 four months more than 40 per cent of the settlers had died in what was 

 possibly an outbreak of malaria. By 1619, the slave trade also was begin- 

 ning to influence the malaria situation in Virginia. Along the Carolina 

 and Georgia coasts, malaria gradually increased with the establishment 

 of rice plantations, since the practice of flooding the fields provided 

 breeding grounds for anopheline mosquitoes. The cultivation of rice was 

 gradually extended southward. As a result, malaria flourished and the 

 prosperous coastal region soon became the most intensely malarial. The 

 disease also spread northward to New England, producing outbreaks in 

 Massachusetts in 1647, 1650, and 1668. Thus, a century before the out- 

 break of the American Revolution, malaria had become established 

 along the Atlantic coast from Massachusetts to Georgia. The Revolu- 

 tionary War introduced susceptible foreign troops into the malarial re- 

 gions along the coast and probably helped to spread the disease in the 

 southeastern area. 



The close of the Revolution ended restrictions on migration. The 

 result was a westward movement of native easterners and immigrants. 

 Malaria accompanied the early migrants over the Appalachians and 

 beyond the Alleghenies to become endemic along the trails. Later 

 settlers passed through these malarial regions on their way westward 

 and helped to extend the disease into new territory. By 1850 most of the 

 United States — with the exception of the western plains and deserts, 

 northern Minnesota and Wisconsin, and the Appalachian and Rocky 

 Mountain highlands — was afflicted with malaria. The disease extended 

 from the Atlantic to the Pacific and from the Gulf of Mexico to the 



