Now largely a tropical disease, malaria was once a global blight.
Aug 4, 2008, Vol. 13, No. 44 • By KEVIN R. KOSAR
The Making of a Tropical Disease
In 1881, the eminent Philadelphia publishing house Presley Blakiston began selling Joseph F. Edwards's Malaria: What It Means and How Avoided. In it, Edwards, an M.D. and author of other useful monographs, such as Constipation Plainly Treated and Relieved Without the Use of Drugs, complained that too many "incompetent physicians" attempting to hide their "want of penetration in diagnosis" had confused matters. The good doctor would set matters aright.
"I will define malaria for you," he promised, "and will furnish the definition in two words, BAD AIR." This blight on man's health was to be distinguished from another affliction, which he termed "intermittent fever," a mysterious affliction that caused dreadful spells of chills and fever. The cause of the latter was due to a "special, mysterious, unrecognized agent." Malaria's cause, however, was obvious--"Everything that has life, be it animal or vegetable, MUST DIE. Everything that dies MUST DECOMPOSE, and everything that decomposes MUST PRODUCE BAD AIR. . . . Therefore, it is self-evident that the surest way to avoid malaria is remove this matter from your presence while it is undergoing decomposition." Q.E.D.
Dr. Edwards, for sure, was not the first person to misconstrue malaria's nature. For at least two millennia scientists, naturalists, and others had gotten it wrong, blaming angry gods, unbalanced humors, and swamp gas. Indeed, as Edwards's example shows, even the best informed could not agree on the affliction's causes, or even its name. Malaria is the accepted nomenclature today, but in centuries past it has been called paludisme, swamp fever, and ague.
What all observers could agree on, though, was that malaria tended to occur in summer and autumn, and that it was--and still is--a god-awful pestilence. The afflicted may first feel minor symptoms, such as a headache and muscle pains. Then come horrendous chills, a skyrocketing fever, and pouring sweats. The spleen swells, anemia may set in, and the victim might fall comatose, in some cases with his limbs thrust out in frozen contortions. The fortunate evade death, but remain susceptible to reinfection throughout their lives.
Nobody was safe from it; malaria has killed millions, from the humblest field worker to eminent figures such as Alexander the Great, Pope Leo X, and Oliver Cromwell.
Discerning the causes of malaria required both technological advances and overcoming old ways of thinking about disease. Aided by microscopes and advances in medical science, researchers began to unravel the mystery of malaria. In 1880 French physician Charles Louis Alphonse Laveran discovered parasites (malaria plasmodium) in the blood of malaria victims. Around the fin de siècle, the British physician Ronald Ross found that the Anopheles mosquito could transmit malaria plasmodium from one bird to another, while the Italian researchers Giovanni Battista Grassi, Amico Bignami, and Giuseppe Bastianelli demonstrated that the same mosquito could spread this parasite from human to human.
Today, we have a pretty good grasp of the mechanics of malaria. The -Anopheles mosquito carries the plasmodium parasite, which it passes on to humans when it bites them. Plasmodium quickly travels through the circulatory system to the liver, where it takes up residence in liver cells, and multiplies. After a week or two, the liver cells burst, sending the disease into the bloodstream. Thereafter, the buggers penetrate blood cells and multiply until these cells burst and scatter still more pestilence in the circulatory system. (This recurrent cycle of bursting red blood cells accounts for the waves of fever that the victim experiences.)
The immune system and spleen work mightily to kill off the infection, and some victims recover. Too often, though, the victim's body cannot keep up with the exponential reproduction of the parasite. Red blood cells die en masse, the organs fail for want of oxygen, and the victim convulses and dies.
Armed with this knowledge, mankind has taken the battle to malaria. Draining swamps and oiling stagnant pools reduces the breeding grounds for Anopheles mosquitoes. Sleeping under mosquito nets can keep individuals from being bitten, and spraying DDT and malathion has killed off zillions of mosquitoes. Chloroquine, artemsinin, and other medications can disrupt the parasite's reproduction, thereby helping victims' bodies to defeat the pathogen. Isolating the afflicted in medical facilities prevents mosquitoes from biting them and spreading plasmodium to others.