Scientists unraveling malaria genes

A dull, lingering headache was Melissa Palka's first sign that something was wrong. Unaffected by aspirin, it slowly worsened, taxing her as she went about her work teaching students at a missionary school in the West African nation of Togo.

After three days, Palka was stricken with deep chills -- the sort of doubled-over, teeth-chattering that comes with a bad virus. Shivering beneath quilts piled deep despite the warm climate, she realized she had malaria.

She had struggled with the disease many times before, as had her husband and three children, during their six years at the evangelical Lutheran mission. But none of them had endured a case as bad as the one Palka suffered through two years ago.

The chills gave way to fever. Even lying on the cold concrete floor of her simple home couldn't cool her. Mostly, she recalls her utter exhaustion.

"I remember wanting to fold clothes because there was so much housework to do -- but I couldn't even sit up in bed. I just didn't have any strength left," she says.

Two common malaria drugs failed to bring her disease under control. Finally, her husband, John, drove her eight hours to a hospital, where more than a week of treatment with intravenous drugs pulled her through.

Last year Palka, now 37, returned with her family to Park Ridge, Ill. The Palkas are survivors of one of mankind's most ancient scourges -- one that is on the rebound.

The first line of defense

But even as the disease appears to expand its reach, scientists are peeling back the secrets of the parasite and its main insect courier, the mosquito. Researchers say malaria science has entered a new era now that it has decoded the genomes of parasite, mosquito and human.

Malaria was all but eliminated in the United States and Europe years ago. Mosquito control programs, air conditioning and well-built homes with screened windows prevent its return in the modern world. But after being rolled back in the developing world during the 1950s and 1960s, malaria is in the midst of an alarming resurgence.

The most deadly of the four human-infecting malaria parasites, Plasmodium falciparum, is becoming increasingly resistant to chloroquine, the first -- and cheapest -- line of defense against it.

According to the World Health Organization, an estimated 1.5 million to 2.7 million people die from malaria each year, about 90 percent of those deaths occurring in sub-Saharan Africa. The precise death toll isn't known because most victims die in rural homes far from hospitals.

Still, scientists report some recent progress in efforts to find a way to stamp out the disease. Earlier this year, researchers from the United States and Britain announced they had mapped the genome of Plasmodium falciparum, the most deadly of the four parasites that infect humans.

And scientists from 12 nations recently completed a rough draft of the genome of the mosquito responsible for spreading nearly all human malaria cases -- Anopheles gambiae.

"In the past we've looked for targets one by one under a single light, looking at one piece at a time. Now we have the whole genome to look at in its entirety under a big light for all types of targets," said Michael Gottlieb, chief of parasitology at the National Institute of Allergy and Infectious Diseases."The opportunities have never been greater to control malaria."

But for the foreseeable future, malaria continues its comeback.