Scientists may have developed a new tool for combating malaria, according to a recent study in the Proceedings of the National Academy of Sciences.

After more than 20 years of genetic experimentation, researchers have discovered how to breed malaria-resistant mosquitoes that are unable to infect humans with their bites.

"We see a complete deletion of the infectious version of the malaria parasite," said Anthony James, a microbiology and molecular genetics professor at the University of California, Irvine, and the lead author of the report. This can help to "significantly reduce human sickness and death," he added.

With the help of fellow researchers from the Pasteur Institute in Paris, James and his colleagues were able to alter the DNA of Anopheles stephensi mosquitoes, which are major transmitters of the most deadly strain of malaria -- Plasmodium falciparum.

By microinjecting a specially engineered gene into the mosquitoes' eggs, the scientists produced insects that were unable to transmit the disease when they reached adulthood.

More importantly, the gene that James' team created was dominant. In other words, introducing it into a wild population of mosquitoes would achieve the same result as placing a group of brown-eyed humans into a blue-eyed population: gradually, fewer children would be born with the recessive, blue-eyed gene.

This means that releasing the mosquitoes in strategic locations could dramatically reduce the spread of malaria, James said.

A disease poised to spread
According to the World Health Organization, more than 650,000 people died from malaria in 2010, most of whom were African children. Some researchers believe this number could climb even higher due to climate change, which is expected to increase rainfall in many regions. More puddles and swampland would provide additional breeding grounds for mosquitoes -- translating into more cases of malaria (ClimateWire, Nov. 21, 2011).

People who have never been exposed to the disease also run the highest risk of infection, so mosquitoes may spread malaria to countless new victims as they follow the rains into fresh territories, say experts.

To make James' malaria-fighting research a reality, millions of mosquitoes would need to be bred in a lab and released into the wild at key intervals.

"We have to figure out how these things are going to scale up," explained James, who says the process of caring for tropical mosquitoes can be very labor-intensive. "This is not something that people are going to be doing in their garage."

Aside from malaria, he believes, the research could ultimately be tailored to prevent other mosquito-borne diseases, such as the West Nile virus and dengue fever.

"I'm pretty enthusiastic that in five years, we'll have tools we'll be able to use," although the ethical, social and legal aspects will likely slow progress, he said.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500