Next week, the biotech company Oxitec, based in Abingdon, England, will begin raising millions of genetically modified mosquitos at a new factory in Campinas, Brazil. The objective: curb the spread of dengue fever.

These new GM-mosquitos won't target dengue specifically, only other mosquitos -- the main vehicle by which the virus travels. These Franken-bugs will mate with females; but their defective sperm will produce offspring that won't make it too adulthood. The logic goes: by slowing rates of mosquito reproduction, there will be less mosquitos and, eventually, less dengue.

But scientists aren't really sure whether it will work.

Margareth Capurro, a researcher at the University of S�Pounds o Paulo, recently completed a small trial study in Jacobina. Her official report is forthcoming, but she said initial data showed that the GM-mosquitos precipitated a massive drop in the number mosquito eggs. However, that decrease failed to translate to any reduction in incidents of dengue. Capurro said it may be that the trial was too small to affect the disease.

Predictably, Oxitec is still confident in the strategy's promise.

"In every trial we've demonstrated excellent control of the dengue mosquito in an urban setting," said Hadyn Parry, spokesperson for Oxitec.

Only time -- and a larger set of trial data -- will tell whether the technique works. And even if it does, the question remains: will it be cost effective? Raising and releasing GM-mosquitos is expensive, and because they can't pass on their debilitating genetic traits, they must be rereleased every year.