15 October 2002
PROGRESS ON MALARIA
The Boston Globe – The recent news that scientists have decoded the genome of the main malaria parasite and its most common mosquito carrier is an encouraging development in a thousands-year-old battle that lately has been going against humans. The parasite has become resistant to drugs, and the mosquito resistant to insecticides. Science needs new attack points, and the genomes of the parasite and the mosquito should provide some. Malaria has much in common with AIDS. Both kill about 3 million people a year, take their greatest toll in Africa, and are adept at defying the defenses of the human immune system. For good reason, the United Nations Fund provides money for dealing with both these diseases and a third infectious killer, tuberculosis.
Mankind's waning ability to deal with malaria is so alarming that the global fund and other foundations should support all avenues of research opened by the new discoveries, as well as traditional public-health measures like distributing insecticide-laced bed netting and spraying and draining in mosquito-breeding areas. According to Dr. Dyann Wirth, a malaria specialist at the Harvard School of Public Health, the most immediate payoff will likely come from the genome of the parasite, since certain drugs have already been shown to work with enzymes identified in it. The parasite's extraordinary repertoire for variation, she says, makes a successful vaccine a more distant goal.
On the mosquito front, researchers hope that decoding its genes might lead to a new repellant that would work by interfering with the insect's uncanny ability to home in on the blood of human beings and not other animals. While sucking its victim's blood, the mosquito deposits parasites. They find their way to red blood cells and destroy them, causing anemia. The parasites also cause blood to coagulate, leading to fatal blockages of brain blood vessels. Mosquitoes drawing the blood of infected humans ingest the parasites and fly off to infect others.
Other scientists envision fiddling with the genome of the mosquito to produce a harmless one. Even if this bioengineered bug only became common and not necessarily dominant, it could greatly reduce malaria's fearsome toll. But, like any bioengineering, this runs risks: What if the new mosquito presents its own unexpected threat? What if it is harmless and becomes dominant, but human beings lose any latent immunity they have against the parasite and then a new carrier emerges to infect humans made even more defenseless? We should be cautious, Wirth said, but not "to the point of inaction."
The United States should also be far more generous in supporting the Fund and other entities financing the fight against malaria and the other massively fatal diseases.