Randolph E. Schmid, Associated Press
March 20, 2007 — Researchers have developed a malaria-resistant mosquito, a step that might one day help block the spread of an illness that has claimed millions of lives around the world.
When they fed on malaria-infected mice, the resistant mosquitoes had a higher survival rate than nonresistant ones, meaning they could eventually replace the ones that can carry the disease, according to a report in Tuesday's issue of Proceedings of the National Academy of Sciences.
Jason Rasgon of the department of molecular microbiology and immunology at Johns Hopkins University cautioned that the research so far is only a proof of principle and any field tests remain far away.
Nonetheless, it's a goal eagerly sought by scientists in hope of developing a practical way of blocking the spread of malaria.
According to the federal Centers for Disease Control and Prevention, an estimated 700,000 to 2.7 million people die of malaria each year, 75 percent of them African children.
Working with the mouse form of malaria — not the human type — Rasgon's team was able to genetically engineer mosquitoes that were resistant to malaria.
Malaria infection does exact a toll on mosquitoes and in laboratory work they found that the resistant insects were able to outcompete nonresistant mosquitoes.
Starting with the same number of resistant and nonresistant mosquitoes, they found that after nine generations the resistant type made up 70 percent of the population — raising the possibility of replacing regular mosquitoes with resistant ones that don't spread disease.
However, Rasgon stressed that in the lab work the insects were infected with a higher amount of the parasite than occurs in nature, and a larger proportion of the mosquitoes were infected.
"This was proof of principle," Rasgon said in a telephone interview. "The next step would be to work in a system more epidemiologically relevant" but still in the lab.
"We're not anywhere near a field release," he said. Now they need to turn their attention to working with human malaria and trying to engineer a mosquito resistant to that.
