Malaria isn't something most Americans think a lot about. The disease was eliminated here 50 years ago as it was in much of the industrialized world. With that victory malaria research nearly came to an end as well. However, episodes like the recent SARS crisis have made the world seem a smaller place and infectious diseases more threatening. Malaria is once again getting the kind of attention health experts say it deserves. Reporter Mike Osborne looks at some of the more innovative approaches to malaria control.
Nirbhay Kumar is an Indian scientist involved in malaria research at Johns Hopkins University in Baltimore, Maryland. Unlike most of his American colleagues, Dr. Kumar has experienced the disease first hand. He contracted malaria while still living in India and relapsed twice before being cured.
"I know how miserable I felt," recalls Dr. Kumar. "I remember clearly the fever, the chills and the sweating - the three symptoms of malaria paroxysms that I experienced when I was infected with this parasite. Clearly the parasite is very smart in terms of being a biological organism that has evolved over the last millions of years and has learned to survive in the presence of all the hostile mechanisms that the human body presents to the parasite."
But malaria research is also evolving. A worldwide collaborative effort recently sequenced the entire genetic code of the malaria parasite. Dr. Kumar's team at Johns Hopkins used that gene map to target the parasite's reproductive cycle. They've already successfully tested several vaccine candidates on mice.
"We are currently testing the same vaccines using non-human primates," says Dr. Kumar. "These are research monkeys and once again in these trials we have had some very remarkable success. Somewhere between ninety and ninety five percent blocking of the parasite's transmitability. We are also looking forward to taking them to the next step. That is to start discussions about the possibility of human trials for these DNA vaccines."
Researchers at Harvard University's Malaria Initiative are using those same genetic tools, but taking a very different approach. Dyann Wirth and her team are trying to circumvent the problem of malaria resistance by designing multi-drug cocktails that target several vulnerable points in the parasite's genetic structure at the same time.
"Drug interventions have always been targeted at a single enzyme in a single pathway that's deemed essential for the organism," explained Ms. Wirth, "but we know based on history that such approaches are effective in the short-term resistance will in fact limit the life of any such drug. So perhaps it's time to think in a more systems approach where we might target an entire pathway, Thereby reducing the frequency with which resistance could occur in all the steps of the pathway simultaneously."
At the National Institutes of Health in Maryland, researchers have taken yet a third approach. Thomas Wellems and his colleagues are looking for vulnerabilities in the mosquitoes that transmit the malaria parasite to human hosts. "Eventually, we may be able to boost the mosquito immunity or somehow prevent the parasite infection of the mosquito," says Mr. Wellems. "If that can be done, you have perhaps a very potent tool to block the transmission of this disease in the field."
Even some of the older weapons in the anti-malarial arsenal are getting a high tech makeover.
"Most mosquitoes bite people at night," points out Robert Ridley of the Geneva-based World Health Organization. "Sleeping under a bed netting helps protect people from getting those bites. It's been found that if you treat those nets with an insecticide, that that dramatically reduces the chances of you being bitten."
New manufacturing techniques allow the insecticide to be permanently embedded in the fiber of the bed netting, so there's never a need to reapply it, and the netting is still quite inexpensive.