Sunday, December 17, 2006

The ultimate swatting of the mosquito

Mosquito-borne diseases are on the rise worldwide. Malaria, over which much energy has been expended to try and control is actually spreading in many areas of the world. The problem is, how do you get rid of all those blood-hungry mosquitos? Unless, you accept that you can't get rid of them at all.

Bio-engineering is stepping up to change the DNA of disease carrying mosquitos. Getting rid of them might not work, but rendering them harmless might be within the realm of possibility.

Eliminating the pests appears impossible. But scientists are attempting to re-engineer them so they cannot carry disease. If they manage that, they must create enough mutants to mate with wild insects and one day to outnumber them.
Researchers chasing this dream, including an N.C. State University entomologist, know they may court controversy. Genetically modified crop plants such as soybeans, corn and cotton have become common in the United States, but an altered organism on wings would be a first.
Of course, messing with genetics of anything will bring a storm of protest.

Critics of bio-engineering, especially in Europe, view some genetic alterations as unnatural, even monstrous. People fearful of so-called Frankenfood could sound similar alarms over Frankenbugs.
There is an ethical dilemma involved. This is genetic engineering and an attempt to alter a species. The intention is to prevent the spread of disease, but it does start one to wondering. Is there an aspect of genetic engineering that could come back to bite us?

The genetic tinkering is focused at first on dengue, a tropical virus re-emerging in Asia, Latin America and Africa. While dengue claims a fraction of the million or more victims that malaria kills annually, it strikes 50 to 100 million people each year with severe flu symptoms. Outbreaks disrupt families and communities and overburden health systems.
Dengue is a good starting point because it is transmitted almost exclusively by a single mosquito species - the smallish, striped-legged Aedes aegypti - while the malaria parasite is carried by several. Focusing the effort on just one bug simplifies the science.
"If you can do this with dengue, you can envision doing it with malaria," Gould said.
To try to build a less dangerous Aedes aegypti, scientists broke a huge job into smaller chunks. First, they needed a means to make female mosquitoes immune to dengue. Only females drink blood (males prefer nectar), and only insects infected with dengue can spread it.
A breakthrough this year at Colorado State University may help. Molecular biologists there stitched laboratory-made DNA into Aedes aegypti that blocks dengue from reproducing in a bug's gut. That stops dengue from getting into mosquito saliva, which deposits the virus into human bloodstreams.
The change is permanent and passed on to offspring.

It's worth reading the whole article... and certainly the ethics are open to debate. I tend to be less chauvanistic about such things, particularly where they might have the effect of ending a persistent and devastating disease.
I can't help but feel, however, that playing with the DNA of something so simple as a bug might eventually come back to haunt us.

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