Malaria’s probable arrival in Rome in the first century AD was a turning point in European history. From the African rain forest, the disease most likely traveled down the Nile to the Mediterranean, then spread east to the Fertile Crescent, and north to Greece. Greek traders and colonists brought it to Italy. From there, Roman soldiers and merchants would ultimately carry it as far north as England and Denmark (Karlen, 1995).
For the next 2,000 years, wherever Europe harbored crowded settlements and standing water, malaria flourished, rendering people seasonally ill, and chronically weak and apathetic. Many historians speculate that falciparum malaria (the deadliest form of malaria species in humans) contributed to the fall of Rome. The malaria epidemic of 79 AD devastated the fertile, marshy croplands surrounding the city, causing local farmers to abandon their fields and villages. As late as the 19th century, travelers to these same areas remarked on the feebleness of the population, their squalid life and miserable agriculture (Cartwright, 1991). The Roman Campagna would remain sparsely settled until finally cleared of malaria in the late 1930s.
In India and China, population growth drove people into semitropical southern zones that favored malaria. India’s oldest settled region was the relatively dry Indus valley to the north. Migrants to the hot, wet Ganges valley to the south were disproportionately plagued by malaria, and other mosquito- and water-borne diseases. Millions of peasants who left the Yellow River for hot and humid rice paddies bordering the Yangtse encountered similar hazards. Due to the unequal burden of disease, for centuries, the development of China’s south lagged behind its north.
Although some scientists speculate that vivax malaria may have accompanied the earliest New World immigrants who arrived via the Bering Strait, there are no records of malaria in the Americas before European explorers, conquistadores, and colonists carried Plasmodium malariae, and P. vivax as microscopic cargo (Sherman, 1998). Falciparum malaria was subsequently imported to the New World by African slaves initially protected by age-old genetic defenses (sickle cell anemia, and G6PD deficiency) plus partial immunity gained through lifelong exposure. Their descendants, as well as Native Americans and settlers of European ancestry, were more vulnerable, however. Deforestation and “wet” agriculture such as rice farming facilitated breeding of Anopheles mosquitoes. By 1750, both vivax and falciparum malaria were common from the tropics of Latin America to the Mississippi valley to New England.
Malaria, both epidemic and endemic, continued to plague the United States until the early 20th century. It struck presidents from Washington to Lincoln, weakened Civil War soldiers by the hundreds of thousands (in 1862, Washington, D.C., and its surroundings were so malarious that General McClellan’s Army en route to Yorktown was stopped in its tracks),