Weaving a weapon against malaria

CorrespondentAugust 23, 2010 

— For most people in North Carolina who are bitten by a mosquito, the result is no worse than an itchy welt. But for people in tropical countries, mosquito bites often cause sickness and death from malaria.

Now an N.C. State University researcher aims to stop the disease spread by halting these insects in their prime, putting a dent in the estimated 243 million cases of malaria reported worldwide.

A mosquito usually lives up to two weeks, just enough time for a malaria parasite to mature and infect the insect's victims. But diatomaceous earth - ground-up fossilized algae that is nontoxic to humans - is an insecticide that can kill mosquitoes in only a few days, said Marian McCord, a textile engineer at N.C. State.

"It's very hard to keep a mosquito from biting you, and bed nets are just a physical barrier that can tear," McCord said. "With diatomaceous earth, we can injure a mosquito, shorten its life span, and potentially prevent others from becoming infected with malaria."

As natural bait, the chalky, abrasive diatomaceous earth attracts insects. When a mosquito lands on it, the substance agitates and damages the waxy outer layer of the mosquito's exoskeleton, making it susceptible to dehydration and disease. The injuries cut the mosquito's life span to one or two days, eliminating its ability to transmit malaria. The insecticide is also effective against other pests, including bed bugs.

McCord said diatomaceous earth could be applied to textile materials, such as bed netting or upholstery, or scattered where mosquitoes land after they've eaten a meal.

The research is a step forward in fighting the spread of malaria, said Guirong Wang, a biological sciences researcher studying mosquitoes at Vanderbilt University. It is important, however, to determine the proper method for using diatomaceous earth safely.

"Using this method to shorten mosquito life spans is a great idea since the particles used are nontoxic to humans and are environmentally friendly," Wang said. "The question is how to use the diatomaceous earth in the field because, while it's not toxic, it may adversely affect human lungs if used at a large scale."

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