We've plastered them with pesticides and warded off their bites with chemical-soaked nets. But centuries after the war on mosquitoes began, these carriers of malaria still deliver their killing bites in most developing countries of the world.
In her most recent book, The Fever: How Malaria Has Ruled Humankind for 500,000 Years, U.S. science writer Sonia Shah begins her chronicle of malaria's history by recalling the fear she felt as a child as she lay in bed in India, watching the mosquitoes perch on the mesh above her body.
“It is hard to fall asleep knowing they are there, watching me, but eventually I drop off and my tensed body uncurls,” she recalls. “They sneak into the gaps my protruding limbs create, and feast.”
The Fever: How Malaria Has Ruled Humankind for 500,000 Years, by Sonia Shah, Farrar Straus & Giroux, 307 pages, $29.95
Shah weaves a compelling tone throughout her book, using her descriptive-writing spell to bring the reader through failed malarial eradication programs even as smallpox and polio vaccinations succeeded.
Most surprisingly, she shows how humans exploited malaria for their own gain, both to protect civilizations and to destroy them.
The swamps beside Rome bred mosquitoes for thousands of years, but the outlying locals developed a higher resistance to the disease than foreign invading armies.
That approach worked well until the Second World War, when the retreating Germans flooded more of the farmland and carried the mosquitoes further into previously untouched Roman communities, deliberately spreading malaria and sickening hundreds of thousands.
An American anti-malaria poster— The National Library of Medicine
Malaria was also considered collateral damage in the pursuit of other goals. United States dam companies, well-aware that the still waters their machines required would also breed mosquitoes, ignored the malaria outbreaks until legislation forced them to change their practices.
As Shah shows, only in the past few decades has the fight begun to change.
She has an eye for picking the anecdotes of history that stick out, such as the hapless Scottish pioneers ridiculed by their peers after malaria felled their efforts to settle Panama.
Sometimes, however, her flair for the dramatic begins to override the narrative considerations of the book. At one point, she delineates the various types of mosquitoes, and why some are more prone to carrying malaria strains than others.
She makes an admirable effort at description, but a diagram of the different strains would have been easier to keep straight than scientific definitions, especially given that she refers to these strains repeatedly for the rest of the book.
Shah usually does use her storytelling skills to better purpose, though, mainly to illustrate the mostly fruitless efforts to contain this disease.
Most of the progress humans made, she points out, was through coincidence rather than by concerted effort. Paving over swamps in the rural southern United States removed mosquito habitat and cut the incidence of malaria to almost nothing.
In Britain, farmers imported the Dutch idea of rotating crops rather than leaving fields fallow for several seasons in between harvests. With more crop available, livestock populations flourished. Shah cites a 1937 book, Lewis Wendell Hackett's Malaria in Europe, that states when an English variety of mosquito is between an exposed cow flank and a human, four out of five times it will land on the animal.
This whittled down the disease to barely noticeable levels on the island.
By contrast, more recent efforts such as Malaria No More's treated nets distribution program in Africa are not as successful, she says. There is a gap in reporting the number of nets actually used, Shah points out, when talking about the millions distributed in the region. She describes locals blithely washing the nets to keep them clean, stripping the mesh of the very chemicals needed to make them effective.
Also, in an area of limited resources, it's often hard to convince parents that vulnerable children are worth shielding with the nets.
Shah's book weaves history and science into one tale of malarial woe, although where she succeeds best is in the history.
As for what's to come, Shah provides very little guidance in her book – perhaps because it is so uncertain.
She berates publicly funded groups such as the World Health Organization for all but shutting down their efforts to track malaria, making it difficult to figure out just how many cases there are worldwide.
A look at the WHO website shows a 2010 fact sheet stating 273 million cases of malaria happen annually, with one million people dying every year. Shah says the statistics probably understate the problem, but – given the scant tracking she finds – can only speculate on what the true number would be.
Shah also expresses doubts about privately funded anti-malaria campaigns, such as that put on by the Bill & Melinda Gates Foundation. Scientists working for those groups can be swayed by political interests, she says, casting doubt on the validity of any of their research.
She offers no solution for this dilemma.
As for the issue of climate change, and whether that will bring malaria once again into Massachusetts or even southern Ontario, Shah doesn't touch the issue at all, focusing only on airplane-borne transmission as a viable path for the disease to take to North America.
“The entire economy, it is said, would have to break down in order for malaria to resettle in developed nations such as the United States,” she writes. “And yet mosquito-borne West Nile virus and Japanese encephalitis have spread unchecked.”
Almost makes one want to buy a mosquito net.
Elizabeth Howell is a freelance science journalist based in Ottawa.
