Killing them softly: Andrew Read’s tactics would stop mosquitoes without resistance

Andrew Read is firing some of science’s latest salvos in the fight against malaria, including a resistance-proof green pesticide

Vector-borne diseases (VBDs)  – deadly viruses and bacteria born by mosquitoes, ticks and fleas – have been gloomy landmarks on the pages of human history, particularly after massive scourges like the fifth-century Plague of Justinian wiped out some 25 to 100 million people in the Eastern Roman Empire and heralded the beginning of the Dark Ages in Europe. And #justonebite from a disease-carrying insect, as the World Health Organization (WHO) Twitter campaign for World Health Day reminds us, is all it takes to contract one.

Mosquito eggs hatching in water. Image: Shutterstock

Mosquito eggs hatching in water. Image: Shutterstock

Malaria kills some 627,000 people each year; in 2012, about 460,000 of them are children who died before their fifth birthday – that’s one child death per minute.  Dengue is otherwise known as “bone-break fever,” due to its wracking effects. Chikungunya, a virus spreading rapidly in the Caribbean, brings headache, joint pain and rashes. No wonder just thinking about these gives us the shivers, a fact Bill Gates drove home when he released a jar of mosquitoes into the room at his TED talk in 2009, saying, “Not only poor people should experience this.”

This unsettling move was prescient; we normally think of these diseases as problems only in poor nations like many in Africa, but thanks to globalization and climate changes they’re getting closer to or diving more deeply into the U.S. Someday, West Nile virus, dengue and perhaps Chikungunya may become facts of life here.

Many of these are killers without a cure, so humans have set our wits to defeating them one way or another.  We’ve tried pesticides; environmental control; shields like clothing and bed nets. TEDMED 2012 speaker Andrew Read, biologist and Director of the Center for Infectious Disease Dynamics at Penn State University, has other ideas: He’s attacking viruses where they live, inside a mosquito’s body.

Read is working with Mathew Thomas, a fellow entomologist, to grow a pathogenic fungus that infiltrates a mosquito’s organs, eventually killing it before the malaria parasite it may harbor matures enough to become contagious, a period of about 12 days. The fungus, which shows no harm to humans, can be sprayed on walls, floors and standing water inside a home.

The fungus aims to be an evolution-proof insecticide. Indoor spraying is still a cornerstone of malaria control, but mosquitoes eventually breed resistance to strains of pesticides if they’re killed immediately, and we don’t have that many new chemical options with which to attack them. Plus, killing all of the world’s mosquitoes could have unforeseen ecological consequences. Instead, Read’s formula kills the bugs more slowly, so that the female has time to lay eggs before expiring.

Read has devoted the majority of his career discovering how infectious diseases evolve, particularly the malaria parasite. As he discussed at TEDMED 2012, there are two ways to combat resistance:  a “drugs-bugs” arms race, in which the bugs are already slowly winning; or evolutionary management, trying to shape the bug populations of the future, which which we’ve done a lousy job so far, he says, in part because many scientists don’t fully understand evolutionary biology.

“If we’re really serious, we’ve got to start measuring things, like the selective forces happening when we hit these bugs. We need to think if we can retard or even stop the evolution that undermines our marvelous technology.

“When we attack life, life evolves back. We are picking  a fight with natural selection, and natural selection is one of the most powerful forces in the universe. Going into a fight without Darwin is like going to the moon without Newton,” Read said in his talk.

Nevertheless, his solution hasn’t yet gone to trial. Funding for his efforts and similar ones is scarce, Read says, adding, “Killing bugs is just not sexy.” The global research and development budget is small in proportion to the severity of malaria’s harms. Of that, the vast majority goes toward tinkering with chemical solutions to kill the messengers, while only about 4 percent goes toward actual vector control; that may change, Read says, as resistance continues to build, as it is in some areas, including West Africa.

If diseases in Chikungunya do spread into the U.S., and there is political pressure for a greener, non-chemical solution, ideas like his may gain more traction. One sign:  His colleague Matthew Thomas is working on a fungal agent to kill bedbugs — an idea that’s already received much attention as their numbers grow in the U.S.

Stacy Lu