July 27, 2010, 11:07 a.m.
Malaria is spread through mosquitoes that have been infiltrated by the Plasmodium parasite.
Malaria, the mosquito-borne infectious disease, has been almost entirely eradicated in the United States for the past 60 years, but continues to infect millions of people around the globe, mainly in parts of sub-Saharan Africa and in subtropical areas.
Each year, between 300 million and 500 million people are afflicted with malaria. The main typical symptoms are fever and chills, but several complications — which can lead to convulsions, hallucinations and even death — occur in a small percentage of cases.
In The Fever: How Malaria Has Ruled Humankind for 500,000 Years, journalist Sonia Shah weaves together a social history of the disease, which has plagued humans for thousands of years and shows no sign of slowing down, despite being treatable with drugs.
In an interview on Fresh Air, Shah tells Terry Gross that prompt treatment and knowing where the infected mosquitoes live and breed are the best ways to avoid malarial infection.
"The trick is knowing where those mosquitoes are living, and building our habitats far away enough so they don't bite us — and [then] protecting ourselves during the times that they bite," Shah explains. "These are things that entomologists have figured out in many places. ... [And] the [malarial] treatments we have actually kill the parasites in our bodies so that we're not infective anymore. So if we get prompt treatment, [we] can also start to end malaria, and of course that is what we've done here in the United States. Prompt treatment and changing the
Sonia Shah is a journalist whose work has appeared in The Washington Post, The Boston Globe and other publications.
On the malaria parasite that infiltrates mosquitoes
"The parasite is called Plasmodium. It's a protozoan. It's a very wily little creature. It transmogrifies into about seven different forms during its life cycle which vary not just in how they look but also in their physiology. It reproduces sexually and asexually, but all of this takes place inside the bodies of mosquitoes for half their life, and the other half of [the Plasmodium's] life is spent inside whatever host they're targeting. And different malaria species target different hosts. So for us, there's at least five malaria parasite species — these species of Plasmodium that infect humankind. And what they do is they come into our bodies in the saliva of a mosquito. They hide in our liver for a while, but what they're really after is the hemoglobin in our red blood cells, so that's what they feast upon, and then they leave to go on and infect another person. So it's this cycle of being infected by malaria parasites and having them feed on our red blood cells — the hemoglobin in our red blood cells — that makes us sick from malaria."
How malaria spread
"Africans carrying malaria parasites walked out of Africa in prehistoric times and they infected Asia and Europe with malaria parasites, and then when Europeans came over to the New World, they brought malaria parasites over with them to the New World. Probably the Americas were not affected with malaria before the Europeans came over because people had to walk over the Bering land bridge, and that was cold — and that took time — and probably parasites would have died out in their bodies before mosquitoes could pick them up. But once we started sailing over, that's a lot faster. Malaria parasites can stay dormant in the body for many months, and there's actually other malaria parasites that can stay dormant in the body for up to 70 years, so if you can wait that long between mosquitoes biting you, you can pass on malaria."
How the symbiotic relationship between the mosquito and the malaria parasite developed
"Mosquitoes and the parasite probably evolved together. So the parasite has vestigial machinery inside of it that suggests that it once photosynthesized. So it was probably some kind of algae floating in the water. So it probably partnered up with mosquitoes pretty early on, since mosquito eggs are hatched inside the water and the larvae are formed in bodies of water. So they probably were together for a lot longer than the parasite started infecting us. But mosquitoes take these blood meals. As we all know, the itchy bites that we get are from the female mosquito trying to suck our blood. And the reason they are taking blood is not for food for themselves, but to nourish their eggs. So that's, evolutionarily speaking, such a hugely important thing to do — to secure the next generation. So the mosquito will actually risk her life to get a few drops of blood to feed her eggs because, of course, taking that blood meal for a tiny little mosquito is incredibly dangerous. Not only can they be easily swatted away and killed by the animals that they take blood from, but once they take the blood, they get filled up with such a huge volume of blood that they can't fly — and obviously, it needs to be able to fly to avoid predators and things. So it risks its life to do that. So that makes the parasite's exploitation of the mosquito's behavior in this so wily because the mosquito's not going to give up its blood meal. It's more than food. It's reproduction."
On the possibility of a malarial outbreak in the United States
"It's not that the parasites aren't here. It's that, if you got that sick you would spike a 103-104 fever and you would run to the hospital right away and you would get prompt treatment. ... The idea is that malaria could come back to the United States, but only if our public health system really fails."
by Sonia Shah
The view through the mosquito net is blurry, but I can see the thick skin of grime on the leading edge of each blade of the ceiling fan as it slowly whirs around, keening alarmingly. This is how it was every summer when I visited my grandmother's house in southern India. While my cousins snore on the bed mats laid across the floor beside me, glistening bodies bathed in the warm night breeze, my sleeping mat is ensconced in a hot, gauzy cage. The mosquitoes descend from the darkened corners of the whitewashed room and perch menacingly on the taut netting, ready to exploit any flicker of movement from their prey within. It is hard to fall asleep knowing they are there, watching me, but eventually I drop off and my tensed body uncurls. They sneak into the gaps my protruding limbs create, and feast.
In the morning, all my hard work of trying to fi t in, to overcome the Americanness of my suburban New England life, has been undone, for my Indian cousins are smooth and brown while I am speckled with bleeding scabs. My grandmother vigorously pats talcum powder over my wounds, the white powder caking pink with congealed blood, as my cousins snicker. I don't understand how they escape unscathed while I am tormented. But incomprehension is part of the package of these childhood summers in India. Just outside my grandmother's house ragged families huddle in rubble along the road and use the train tracks as their toilet. They wave their sticklike arms in my face and moan woefully when we pass by on the way to temple, caricatures of beggars. One boy's leg has swollen to the size of a log, and is gray and pimpled, from some disease brought on by a mosquito bite. My grandmother tightens her grip on my hand. We give the children nothing. I can't understand this, either. When we get to the white marble temple, it is full of incense and golden statues encrusted with diamonds and rubies — to my seven-year-old mind, the very picture of prosperity.
Part of me despises my estrangement, my incomprehension, the fact that I must sleep under the suffocating net and take the malaria pills while my cousins don't. But part of me is secretly glad. The boy with the swollen leg frightens me. The family who lives on the curb frightens me. India frightens me. These fears, for the girl who is supposed to be Indian but isn't, are unspeakable.
When no one is looking, I crush the mosquitoes' poised little figures with my palm and smear the remains on a hidden seam in the couch. Our Jain religion forbids violence of any kind. No eating meat. No swatting flies. My grandmother wears a mask over her mouth while she prays, to protect airborne microbes from inadvertent annihilation in her inhalations, and considers walking on blades of grass a sin. Meanwhile, there I am in the corner, cravenly pulverizing mosquito corpses behind my back, blood literally on my hands.
Back home in New England, the mosquitoes still bite, but there are no nets at night, no pills to take, no scary beggars on the side of the road. We shop for forgettable plastic trinkets at the mall. My fear and loathing of the mosquito are blunted into games of tag. My father calls himself Giant Mosquito, undulates his fingers like proboscises and chases me and my sister. It's scary, but fun-scary. We screech with glee and stampede through the house.
Thirty years later, on the S-shaped land bridge between the North and South American continents, I meet Jose Calzada. Calzada is a mosquito stalker of sorts, and I, the mosquito hater, have come to learn about the local mosquitoes and their exploits. A parasitologist from Panama City, Panama, Calzada spends his time rushing to the scene of disease outbreaks across the isthmus. The mosquito-borne parasite that causes malaria, Plasmodium, is one of his specialties.
It is April 2006. For most of the past century, there hasn't been much work in this field for people such as Calzada. Panama prides itself on being one of just a handful of tropical developing countries to have tamed its mosquitoes and nearly conquered malaria. American military engineers built a canal through Panama in the early 1900s, and forced malaria to retreat to the remote fringes of the country. Since then it has stagnated, primarily in its most benign incarnation, vivax malaria, which is rarely fatal.
But things have changed in recent years, and Calzada has agreed to show me some obscure signs. He emerges from the imposing Gorgas Memorial Institute, Panama's sole health research center. Clean-shaven and trim, Calzada has a slightly worried look in his eyes that is off set by high cheekbones suggesting a perpetual halfsmile. I wait while he meticulously changes out of his work clothes — button-down oxford shirt and slacks — and into a T-shirt and jeans. Climbing into my diminutive white rental car and tossing a baseball cap on top of his backpack in the backseat, he patiently directs me out of the labyrinthine metropolis. Navigating Panama City's congested streets, past shiny skyscrapers and packed cafes, is a task that challenges even my well-honed Boston driving skills.
After twenty minutes heading east out of the city, the road turns quiet. It's a lovely drive, with hills in the distance, verdant pasture and scrub unbroken save for a few elaborately gated houses set far back from the road. Colombian drug lords, Calzada says, by way of explanation. Another hour passes, and the road rises, a glittering lake coming into view, just visible through a tangle of jungle. As we near the water, the pavement ends, and we pull over.
Here, at the end of the road, is the town of Chepo. From what I can see, it consists of a wooden lean-to facing a sleepy roadside cafe. Two police officers amble out of the lean-to, which turns out to be a checkpoint. They take my passport and vanish, leaving Calzada and me to buy a cold drink at the near-empty cafe. As we sit, I can just make them out in the murk within the lean-to, inspecting the blue passport with great care, turning it over and over in their hands as if for clues to some baffling mystery.
Inspection completed, Calzada leads us on foot behind the road. The hillside is green and lush, with a slick red clay track leading to the crest. He heads up and I follow gingerly.
Excerpted from The Fever: How Malaria Has Ruled Humankind for 500,000 Years by Sonia Shah. Copyright 2010 by Sonia Shah. Excerpted by permission of Sarah Crichton Books / Farrar, Straus and Giroux, LLC. All rights reserved.