A disease of poverty, environment and race, malaria kills an estimated 660,000 people – mainly children – every year.
Once prevalent worldwide, malaria was quashed in affluent nations decades ago, largely due to efficient insect control and housing improvements. But as of last year, 104 countries were still plagued by virulent species of parasitic Plasmodium protozoa that live inside female Anopheles mosquitoes and invade human bloodstreams when the insects feed. Half the world’s population remains at risk for malaria, according to the WHO.
Making matters worse, warming temperatures, coupled with deforestation, crop irrigation and other man-made environmental changes, are driving mosquitoes to new grounds across the globe. In sub-Saharan Africa, malaria is now reaching higher altitudes than ever before.
Karatu is one such place. When Artress and his wife moved there seven years ago, they were told “no mosquitoes, you’re above the malaria line,” he said. But “apparently with global warming, there are actually a lot of mosquitoes.”
For communities first encountering the disease, the results can be devastating.
“The appearance of malaria mosquitoes in the African highlands is real,” Mnzava said. “These areas are now prone to malaria epidemics with severe consequences to local populations due to their lack of immunity.”
Pyrethroids losing effectiveness
Developed in the 1970s, pyrethroids are the last new class of pesticides produced for public health uses in nearly half a century.
These synthetic compounds, based on a natural substance found in chrysanthemums, are considered "safe," according to the Environmental Protection Agency. Animal studies, however, have found that pyrethroids alter developing brains, and there have been virtually no studies of their potential effects on human health.
“Given uncertainty about the existence of long-term health effects of exposure to pyrethroids, particularly under realistic scenarios, we should be cautious when promoting pyrethroid products as safe methods for pest control,” a group of environmental health scientists in Canada recently advised.
Nonetheless, pyrethroids are the backbone of all major malaria-control programs. Pyrethroid treatments, provided in a massive, decade-long campaign by U.S. and international aid organizations, have made significant inroads against the disease in recent years. The insecticide saved more than a million lives between 2000 and 2010, according to the WHO.
But reliance on pyrethroids, the only insecticide permitted for mosquito nets and the main ingredient in most indoor sprays, has allowed insects with a gene conferring immunity to flourish. That immunity now threatens to roll back those gains.
The surge of resistance to antimalarial weapons is analogous to today’s spate of “superbugs” that are invulnerable to antibiotics. Both were set off by unsustainable use of chemicals.
“Attacking malaria around the world and using a lot of drugs will generate drug-resistant parasites. And attacking mosquitoes around the world and using a lot of insecticides will generate insecticide-resistant mosquitoes,” said Sir Richard Feachem, former executive director of the Global Fund to Fight AIDS, Tuberculosis and Malaria and current director of the Global Health Group at the University of California, San Francisco.
“We always knew that – no fundamental surprise here – we always knew it would happen,” he said. “What we didn’t know was how quickly it would happen.”