Malaria
JULY 2007
[an error occurred while processing this directive]
|
|
Malaria
|
By Michael Finkel
|
Photographs by John Stanmeyer
|
|
It's easy to list every vaccine that can prevent a parasitic disease in humans. There is none. Vaccines exist for bacteria and viruses, but these are comparatively simple organisms. The polio virus, for example, consists of exactly 11 genes. Plasmodium falciparum has more than 5,000. It's this complexity, combined with the malaria parasite's constant motion—dodging like a fugitive from the mosquito to the human bloodstream to the liver to the red blood cells—that makes a vaccine fiendishly difficult to design.
Ideally, a malaria vaccine would provide lifelong protection. A lull in malaria transmission could cause many people to lose any immunity they have built up against the disease—even adults, immunologically speaking, could revert to infant status—rendering it more devastating if it returned. This is why a partial victory over malaria could be worse than total failure. Falciparum also has countless substrains (each river valley seems to have its own type), and a vaccine has to block them all. And of course the vaccine can leave no opening for the parasite to develop resistance. Creating a malaria vaccine is one of the most ambitious medical quests of all time.
Recent malaria history is fraught with grand pronouncements that turned out to be baseless. "MALARIA VACCINE IS NEAR," announced a New York Times headline in 1984. "This is the last major hurdle," said one U.S. scientist quoted in the article. "There is no question now that we will have a vaccine. The rest is fine-tuning." Seven years of fine-tuning later, another Times headline summarized the result: "EFFORT TO FIGHT MALARIA APPEARS TO HAVE FAILED." In the late 1990s, Colombian immunologist Manuel Patarroyo claimed, with much media fanfare, that he had found the answer to malaria with his vaccine, SPf-66. Early results were tantalizing, but follow-up studies in Thailand showed it worked no better than a placebo.
At least 90 teams around the world are now working on some aspect of a vaccine; the British government, by way of incentive, has pledged to help purchase hundreds of millions of doses of any successful vaccine, for donation to countries in need. The one closest to public release, developed by the pharmaceutical company GlaxoSmithKline Biologicals in collaboration with the U.S. Army, is called RTS,S. In a recent trial in Mozambique, it protected about half the inoculated children from severe malaria for more than a year.
Fifty percent isn't bad—RTS,S might save hundreds of thousands of lives—but it's not the magic bullet that would neutralize the disease once and for all. Many researchers suspect an all-encompassing cure isn't possible. Malaria has always afflicted us, they say, and always will. There is one man, however, who not only believes malaria can be defeated, he thinks he knows the key.
Stephen Hoffman is the founder and CEO of the only company in the world dedicated solely to finding a malaria vaccine. The company's name is Sanaria—that is, "healthy air," the opposite of malaria. Hoffman is 58, lean and green-eyed, with a demeanor of single-minded intensity. "He's impassioned and impatient and intolerant of negativity," is how one colleague describes him.
Hoffman is intimately familiar with the pitfalls of the vaccine hunt. During his 14-year tenure as director of the malaria program at the Naval Medical Research Center, he was part of the team working on the vaccine promised in the 1984 New York Times article. He was so confident in the vaccine that he tested it on himself. He exposed himself to infected mosquitoes, then flew to a medical conference in California to deliver what he thought would be a triumphant presentation. The morning after he landed, he was already shaking and feverish—and, soon enough, suffering from full-blown malaria.
Now, more than two decades later, Hoffman is ready to return to prominence. He couldn't have found a more uninspiring launchpad: Sanaria is headquartered in a dismal mini-mall in suburban Maryland, near a picture-framing shop and a discount office-supply store. From outside, there's no mention of the company's mission. A window badly in need of washing bears the company name in tiny adhesive letters. Hoffman realizes it's probably best if the office-supply customers aren't fully aware of what's going on a few doors away.
Inside, generating a hubbub of activity, are some 30 scientists from across the globe. The lab's centerpiece is a room where Hoffman raises mosquitoes infected with the falciparum parasite—yes, in a quiet mini-mall. Hoffman claims it's the world's most secure insectary. To enter, a visitor must pass through multiple antechambers that are sealed between sets of doors, like a lock system in a canal. Everyone has to wear white cotton overlayers, masks, shoe covers, and gloves. White makes it easier to see a stray mosquito. The air is recirculated, and the insectary is checked daily for leaks. Signs abound: "WARNING! WARNING! INFECTIOUS AGENT IN USE." And hanging on a wall is a time-honored last line of defense: a flyswatter.
The mosquitoes are housed in a few dozen cylindrical containers, about the size of beach buckets, covered with mesh lids. They're fed falciparum-infected blood, then stored for two weeks while the parasites propagate in the insects' guts and migrate to the salivary glands, creating what are known as "loaded" mosquitoes. The loaded insects are transferred carefully to a kiln-like irradiator to be zapped with a quick dose of radiation. Then, in a special dissecting lab, the salivary glands of the mosquitoes are removed. Each mosquito's glands contain more than 100,000 parasites. Essentially, the vaccine consists of these irradiated parasites packed into a hypodermic needle.
Subscribe to National Geographic magazine.
|
|
Top
|
|
