Americas

Until the 1500s, the New World was malaria-free. The great trek across the Bering Strait into North America by malarious Asians 20,000 years ago froze out the mosquitoes and Plasmodium. But then, European explorers, conquerors and missionaries ferried Plasmodium in the warmth of their blood to the soft shores of the Americas.

Malarious Spaniards and their parasitized African slaves spread malaria throughout South America and the Caribbean. Malaria remains a serious problem throughout much of South and Central America. Less known is that for centuries, malaria was the premier disease of the North American continent as well. English entrepreneurs brought their vivax malaria to the Chesapeake Bay colonies, and later to Carolina and the southern settlements. By the mid-1600s, African slaves arrived in the English settlements and introduced falciparum malaria to North America as well. By the 1680s, falciparum had supplanted endemic vivax in the Chesapeake Bay colonies, and the parasites had spread to New England. Each newcomer to the colonies was forced to suffer his or her “seasoning”—a life-threatening bout of malaria.

Virginia was so malarious it was “only good for doctors and ministers,” bemoaned one Scottish settler in 1723. “They who want to die quickly go to Carolina,” added a German commentator in 1737.

Malaria spread into the Mississippi Valley and over the Rockies after the American Revolution, as malarious settlers spread westward. By the early 1800s, malaria had become “the great cause of mortality or infirmity of constitution” in the Mississippi valley, the physician Daniel Drake noted. The fertile lands of the river valley were “exceedingly destructive to health and human life,” a physician noted at the time. “The inhabitants…sooner or later sink into the grave the victims of malaria.” Malaria killed 80 percent of settlers in Pike County, Illinois in the 1820s, and 80 of 600 Norwegian settlers in Wisconsin in 1841. It destroyed an 1830s effort to build a canal between the Great Lakes and the Mississippi river.

In New England and the Mississippi Valley, malaria was a seasonal affair. In the American south, where mosquitoes reproduced and bit year round, malaria was ever-present. Plasmodium falciparum, which dies out when the weather cools and the mosquitoes stop biting (vivax can hang on, since it can retreat into the body and remain in stasis for months), plagued the south. Twice the capital of Alabama was relocated because of malarial fevers; in an 1821-22 malaria outbreak in Catawba, 12 percent of the population perished. Southern falciparum malaria may have played a role in white planters’ increasing reliance on African slave labor, as opposed to poor white or native labor—a significant portion of Africans carried genes that lessened the severity of falciparum infection. The sickle-cell gene, for example, is potentially deadly in double-doses (homozygotes), but confers an advantage against falciparum infection in those with a single dose (heterozygotes). Natural selection weeds out the gene in places where there isn’t much falciparum. In Carolina, the sickle-cell gene circulated as lushly among African slaves as it did in West Africa.

The discovery of American coal deposits unleashed industrial developments that started to push back malaria in the Midwest and New England. The building of the railroads allowed many Americans to move away from mosquito-ridden waterways. The push for greater drainage to reclaim wetlands for agricultural development destroyed millions of acres of mosquito-friendly swamps and bogs. As the spongy land dried out, downstream flooding worsened, and waterfowl and shorebird populations plummeted, but farmlands grew and mosquito habitats steadily disappeared, diminishing the possibilities of malaria transmission.

The Civil War interrupted malaria’s downward slide. From its strongholds in the South, malaria struck out in the bodies of scores of troops. Union troops suffered 1.3 million cases of malaria, leading to 10,000 deaths. In 1864, every single Federal soldier in the Department of the Gulf came down with at least one episode of malaria. As the close of the war, Northern soldiers fanned out across the northern states, heading home. Over half had carried plasmodium parasites within them.

The re-introduced parasite didn’t need a great many mozzies to hang on. Even a handful of willing mosquitoes was sufficient, so long as they survived long enough to gestate and pass on the parasite. (As the late mosquito biologist Andy Spielman wrote, mosquito longevity is “by far” the most important factor in malaria transmission. “An old mosquito is your worst enemy.” )

Malaria outbreaks spread across the increasingly industrialized landscape, plaguing even concrete-covered Manhattan. Manhattan had been built upon a watery idyll of stream, creek, and bog. Madison, Washington and Tompkins Squares, constructed atop cheap, swampy lands rejected by builders as “unfit”, for a brief period after the war became “Dangerous Hot-Beds of Disease and Death,” as a New York Times headline put it.

Malaria hung on in the South until the 1930s. According to the USDA, malaria bled the fledgling postwar US economy of some $1 million a year. In the late 1930s, 62 percent of children in the eastern counties of North Carolina harbored malarial parasites In 1933, President Roosevelt signed two measures to uplift the South: the Tennessee Valley Authority, and the Agricultural Adjustment Act, which would help Southern farmers mechanize their farms. Not only did the TVA dams not trigger malaria, they destroyed mosquito breeding sites. The cheap electricity enriched the region, bringing in better housing and roads. At the same time, the greater mechanization of Southern farms intensified the stream of black sharecroppers leaving their swampy cabins for the city, and the urban areas of the North. Malaria died out as they left.

For more:

Centers for Disease Control: history of malaria
http://www.cdc.gov/malaria/history/index.htm

Pan American Health Organization: Malaria
http://www.paho.org/english/ad/dpc/cd/malaria.htm

St. Julien Ravenel Childs, Malaria and colonization in the Carolina low country 1526-1696 (Baltimore: The Johns Hopkins Press, 1940)

Forest Ray Moulton, ed., A Symposium on Human Malaria with Special Reference to North America and the Caribbean Region (Washington, DC: American Association for the Advancement of Science, 1941)

Erwin H. Ackerknecht, Malaria in the Upper Mississippi Valley 1760-1900 (Baltimore, MD: Johns Hopkins Press, 1945)

Todd L. Savitt and James Harvey Young, eds., Disease and Distinctiveness in the American South (Knoxville, TN: University of Tennessee Press, 1988)

Margaret Humphreys, Malaria: Poverty, Race, and Public Health in the United States (Baltimore, MD: Johns Hopkins University Press, 2001)

“I eat plenty of hog meat and peas and I never had malaria.” -a North Carolina man, 1940s