by Sonia Shah
Meanwhile, supported by both state and industry, Italian malariologists were hot on malaria’s trail. The Italians differed fundamentally from Ross and Manson in their approach to the disease. They conducted interdisciplinary research and embraced the insights of naturalists and of malaria sufferers themselves. While Ross described the malarious Indians he experimented upon as “ people who love filth” and “ really nearer a monkey than a man,”36 the Italian pathologist Amico Bignami considered malaria victims “much better informed about malaria than some medical men.” Visiting malarious areas, he asked locals about their experiences with the parasite, gleaning important clues about its secret ways. “Many precautions which they take against the fever are taken, one would say, to defend them from the sting of insects,” Bignami noted. They avoided going out at night and sleeping outdoors. They closed their leaky windows against insects but not the night breeze, and took “great care of their mosquito curtain,” which they wrapped themselves in every night, regardless of the heat.
All of this led Bignami to hypothesize that it was the bite of the mosquito—not its water or dust or air—that carried Plasmodium to its final destination. Bignami and his colleagues backed up their hypothesis with experimentation. They fed volunteers marsh water, let them inhale dust from malarious areas, and injected them with blood from malaria victims. The water and dust did nothing, but the inoculation indeed sickened volunteers.37
Bignami’s team had made progress on the species of mosquito, too. In 1895, the zoologist Giovanni Battista Grassi had joined Bignami in Rome. Grassi, a highly regarded evolutionary biologist, had described malaria in owls, pigeons, and sparrows, among other birds, finding that each bird species boasted its own unique malaria parasite species. For Grassi, as for any naturalist, the species of the mosquito was as crucial a factor in human malaria transmission as the species of the host and of the pathogen itself. Grassi had already thoroughly described the distribution of mosquitoes in Italy (there were at least fifty species), and of the six species that frequented malarial areas, he had narrowed the suspects to just three: two Culex species and the true Anopheles culprit.38
In 1896, Bignami published his notion that the bite of the mosquito transmitted malaria to humans, and with Grassi, he started experimental work to prove it.39
Manson and Ross, neither of whom ever achieved much financial success, constantly fretted over securing a living. Manson’s tactic was to try to shame the British government into supporting his and Ross’s work, appealing to its sense of national pride. “It is little to our credit,” he told a medical society gathering in 1894, “that continental nations, whose stake in tropical countries is infinitely smaller than ours, are nevertheless just as infinitely ahead of us in this matter.” Ross agreed: it would be so “annoying” if “the Italians do come in first!”40
Manson and Ross fought the Italian researchers’ findings tooth and nail and clung to their misguided hypotheses to the very end. After all, their very livelihoods were at stake. “Bignami is a pure villain,” Ross raged.
He wants to secrete a mosquito theory of his own . . . He wants to bite into the heart of your theory, suck its juices & then bloat & swell into a discoverer—or rather until he is thought to be one . . . He is quite capable of spreading his six legs over your work & calling it all his own . . . if you have not squelched him already you ought to do it.41
Malariology averted the dead end that Ross and Manson urgently steered it into when the two scientists happened upon the same conclusion as Bignami and Grassi, albeit less via methodical inquiry than through serendipity. First, Ross inadvertently discovered Anopheles mosquitoes, hidden deep inside a forest (a local servant pointed them out to him). Because he couldn’t entice any human volunteers—“for several reasons hospital patients . . . are not convenient to work with,” he wrote, “they expect treatment & the papers might talk”42—Ross shifted from humans and their malaria to the more easily captured birds and theirs.43 And while trying to prove Manson’s mosquito-water theory, he encountered a strange, delicate structure inside the torn-off head of a mosquito. “This proved to be a long branching gland of some sort, looking like a coil of large intestine,” he wrote. “I noticed at once that the rods”—sporozoites—“were swarming here & were even pouring out from somewhere in streams.” What was this quivering coil, shuddering with tiny squirming parasites? “I still experience, however, the greatest difficulty in dissecting out the gland itself,” Ross wrote.
It appears to lie in front of the thorax close to the head, but breaks so easily in the dissection that I cannot locate it properly. In the second mosquito however there was no doubt, as shown by evident attachment that the duct led straight into the headpiece, probably into the mouth.
In other words it is a thousand to one, it is a salivary gland.44
In other words, Bignami had been right all along. But Ross and Manson didn’t see it that way. In London, Manson promptly declared that he and Ross had solved the mystery of malarial transmission, presenting Ross’s work on bird malaria to a meeting of the British Medical Association, enlivening his report with dramatic flourishes such as the reading out of a telegram from Ross on his latest results.45 “The fat is thoroughly in the fire,” Manson reported proudly to Ross afterward.46 “You will be lionized when you get home.”47 “Well, I have become unbearable with conceit,” Ross wrote back. “That was a grand charge! I brag openly about it!”48
Of course, Ross had shown that mosquitoes transmit malaria to birds, not humans. Bignami had come out with the correct hypothesis first, and Grassi was the first to experimentally infect a human volunteer with malaria through the bite of an infected mosquito, a result published in 1898. Ross had described some gray, dapple-winged mosquito, while Grassi had fingered Anopheles specifically. The month before Manson’s grand announcement, German bacteriologist Koch announced that he had discovered malaria’s mosquito vector.49
That is, Ross and Manson’s stake to the nineteenth century’s scientific Holy Grail was as assured as one of those tattered flags flapping on Mount Everest. In the august pages of Britain’s leading medical journal, Bignami and Grassi politely cited Manson and Ross and their “interesting observations” on birds.50 The head of the British Medical Association openly said that the Italians had made the major discoveries in malaria’s transmission. When Ross actually went to Italy to visit with Italian researchers, the local papers downgraded him to “an engineer.”51
The Indian Medical Service, which had repeatedly disrupted Ross’s studies, yawned in the face of his fabulous discovery. It forbade him to publish his findings on malaria in birds, and even when it finally gave him time off to complete his investigations, it demanded that he look into other diseases as well as malaria. When he made his big breakthrough, the IMS “congratulated me politely,” he wrote, “but they asked no questions, never sent for me, never ordered anyone to inspect or verify my work, never gave me any assistance.”52
Back in Britain, Ross struggled to secure a well-paying position.53 He went on the offensive, writing angry papers defending the primacy of his work, and insulting other scientists who disagreed with or belittled him. “I might have omitted the word stupid,” he wrote in his memoirs of one such assault, “but the criticism was quite sound and valuable.”54 “Please don’t believe too much of Grassi & Cos.’ work,” he begged one colleague. “Their actual observations have been of the slenderest and . . . the rest is eked out by aid of my reports.”55 “The work on human malaria is only of secondary importance,” he added, a “mere detail” of his work on birds.56
Ross’s vitriol worked. In the end, it was he, not Grassi, who was awarded the Nobel Prize in 1902.57 But much time was wasted in the ugliness. “I hate war and publicity of this sort,” Manson complained.58 And in the meantime, the pace of scientific research into the mosquito question—and with it, Homo sapiens’ first big chance to tackle malaria transmission—ground nearly to a halt.
Public skepticism about the mosquito t
heory of malaria transmission reigned. The notion that Anopheles mosquitoes transmitted malaria, alone, didn’t fully explain common experiences with the disease. Did all species of Anopheles carry malaria? And if so, why was it that malaria raged in places where precious few Anopheles could be found, and was scarce in places where Anopheles rose in giant black flocks? This phenomenon was particularly obvious in Europe, where the malaria vector Anopheles maculipennis appeared to have no relation whatsoever to the prevalence of malaria. European malariologists called the conundrum “anophelism without malaria.” Further, was the mosquito the sole vector of malaria? If so, why was it that in places such as the Netherlands and Germany, fevers started in April and May, months before fat and sleepy Anopheles awoke from hibernation?59
Ross and Grassi’s discovery shed little light on such questions. As a result, many thinkers held that if the mosquito did transmit malaria, there were other, still-undiscovered factors. According to this way of thinking, Ross and Grassi had found just one route among many, and perhaps not even the most important one at that. (Grassi called the elusive transmitter “Factor X.”60)
Countertheories abounded. A paper in the Indian Medical Gazette argued that “proper, filtered water supply” played a bigger role in malaria transmission than “the mere presence of Anopheles.”61 The mosquito theory was just a fad, wrote another author, who claimed to be able to prove with statistical certainty that malaria was a waterborne complaint.62 In fact, according to another, malaria actually was just a “disorder of degenerating white blood corpuscles.”63
Ross and Manson’s response to the missing pieces in their mosquito theory only inflamed the public’s skepticism. Manson organized some poorly received experiments, which convinced few of anything. Meanwhile, Ross wildly proclaimed that he’d be able to extinguish malaria in every city in the tropics within two years.64
Ross’s exaggerations provoked even more exaggerated dismissals among health officials and scientists, who pointed out the folly of attempting to effect mosquito genocides. “I doubt whether, even if the whole population of India were put to the work of filling up all the puddles during the rains, the results would justify the expense,” maintained a British official at a malaria conference in India.65 Indeed, the chairman of London’s Society of Arts said to Ross, “Mosquitoes are every where. They surround us like the air we breathe.”66
In fact, to control malaria transmission, it isn’t necessary to slaughter every last mosquito or avoid every last mosquito bite. Only certain species of the Anopheles mosquito need to be tackled, and even then only in ways that make it difficult for them to transmit the malaria parasite. As Manson pointed out, getting bitten ten times a night in a place where one out of every one thousand Anopheles is infected results in three malaria infections a year. Reducing those bites to one a week would result in just one bout of malaria in ten years.67
In the polarized debate Ross sparked, however, such nuances were quickly lost. “The identification of mosquitoes has become so difficult that it is better to leave it alone,” said the bacteriologist Robert Koch, “so long as there remains anything else to be done in this world.”68 Even in Italy there was little interest in controlling mosquitoes. Nobody seriously considered that all the Italian peasants sleeping in caves in the Campagna could be rid of every last mosquito bite. It was impractical, inconceivable.69 According to the Indian Medical Service’s malaria expert Sydney Price James and the Dutch malariologist N. H. Swellengrebel, mosquito killing was “futile” and a “tyranny . . . over men’s minds” that should be “thrown off,” as they jointly reported for the League of Nations’ Malaria Commission in 1927.70
Ross died in 1932 a bitter, ruined man. “I had lost money over the work, I had received practically nothing but skepticism or even abuse in return, and most of my results were credited to others,” he wrote in his memoirs. “The word ‘malaria’ ” he declared, made him “nearly as sick as the thing itself would have done.”71 To add insult to injury, the species of Anopheles named after him—Anopheles rossi—for years was believed not to transmit malaria.72 When it was finally discovered that it did, it had by then come to be known as Anopheles subpictus, the name bestowed upon it by Ross’s archrival Giovanni Grassi.73
In the decades following Ross’s and Grassi’s discovery, only those willing to flout the scientific conventional wisdom did anything much to minimize the reproduction or biting of malarial mosquitoes. The Italian prime minister Benito Mussolini did, during the 1930s, as a cornerstone of his Fascist revolution. His 549-million-lire scheme to finally drain the Pontine swamps took the lives of more than three thousand workers.74 Industrialists with malaria-threatened rubber plantations in Malaysia did, discovering that disrupting malaria transmission sent other infectious diseases—diarrhea, dysentery, nephritis, abscesses, tuberculosis, convulsions—plummeting as well.75
So, too, did American malariologists. Insect destruction was generally quite popular in the rapidly industrializing United States of the late nineteenth and early twentieth centuries. American farmers, having turned the wilds into feeding troughs for insects shorn of their natural enemies, lived in fear of entomological invasion. Clouds of locusts descended upon the farms of the Mississippi Valley. Gypsy moths stripped every tree in New England of their leaves, and their decaying, crushed bodies sent a stench across the land.76
With insects strangling American economic development, the government had started to invest in entomological research. An early result, in 1901, was an influential handbook called Mosquitoes: How They Live, How They Are Classified, and How They May Be Destroyed.77 Whether or not anti-mosquito campaigns alleviated malaria, they almost always helped improve property values, spur development, and after the First World War, showcase new chemicals, many of which had been refined for use as chemical weapons.
New Jersey state entomologist John B. Smith demolished acres of mosquito habitat in that state’s lowlands, a feat that he claimed more than quadrupled property values. A similar campaign waged on Staten Island, in New York City, triggered a development boom.78 In the early years of the twentieth century, the notorious oil baron John D. Rockefeller created the philanthropic behemoth the Rockefeller Foundation, whose International Health Division quickly gravitated toward the popular anti-mosquito projects. “I can’t recollect when we have been able to remain on our front porches without fighting the blood sucker until this summer,” one grateful local wrote to the foundation. “Thank you again.”79
None of this budged the scientific consensus against mosquito killing in Europe. The Rockefeller Foundation malariologists made the rounds at international scientific meetings, touting their entomological victories, but with notoriously poor data collection and a chronic lack of controlled comparisons, Rockefeller scientists’ optimistic reports left their European colleagues entirely unmoved. The reports didn’t measure whether malaria had declined, nor the complicated role of the many confounding factors—including rainfall, temperature, and the movement of human populations—that may have played a role in any observed changes. In 1927, the League of Nations prepared a report dripping with skepticism about the Americans’ claims.80
Rather than debate the issue and refine their science, the Americans, like Ross and Manson, closed ranks. Enraged American malariologists felt that their dismissive European colleagues couldn’t be bothered doing anything about malaria.81 The U.S. surgeon general pressured the League of Nations (which the United States had never joined) to bury the doubting report, claiming it suffered from “contradictory and often insufficient premises”82—and that was that. The international body never published it.83
Malariologists’ dispute over the antimalarial utility of mosquito killing rested on differing conceptions of the nature of mosquitoes’ carriage of malaria. Simply put, those who believed that all Anopheles mosquitoes carried malaria assumed that killing any Anopheles mosquitoes would help reduce malaria. Those who believed that something other than Anopheles mosquitoes carried malaria presumed
that mosquito killing would do little to reduce malaria.
The truth was that neither side in the debate had it right: it wasn’t that all Anopheles carried malaria, or that something other than Anopheles carried malaria, but rather that only some Anopheles carried malaria. Research into the biology and mysterious habits of Anopheles mosquitoes would have revealed this fact, but both the skeptics and the enthusiasts had deflated funding interest with their conflicting orthodoxies. The American entomologist L. O. Howard, for example, tried to launch a research project on the identification of different species of Anopheles. But “there were many more species of mosquitoes than I had supposed,” with “infinite variations in habit,” he remembered. And “we could not possibly produce such a work as we wished to bring out” on the limited three-year grant Howard had scraped together. Funds to conduct this kind of mosquito research were so thin that the only way Howard figured he could continue the work at all was by dipping into the deep pockets of a fellow biologist.84
And so clues, when they appeared, arrived from obscure, unheralded corners.
First, in 1921, the French entomologist Emile Roubaud speculated that malaria transmission might be linked to some hidden quirk inside the Anopheles mosquito. Say, for example, that malaria-carrying Anopheles in some localities had more teeth, he theorized. They’d be able to bite through animals’ thick hides and therefore would deposit any malaria parasites within them into the dead-end host. Perhaps some other locality harbored mosquitoes with fewer teeth. Those insects would have no choice but to bite thin-skinned humans, and so could effectively carry malaria. The dental difference would explain why not all Anopheles species, such as the European Anopheles maculipennis, seemed to carry malaria.