Originally created 02/17/99

Possible new vaccine fights malaria throughout its life cycle



WASHINGTON -- A team of researchers has discovered a possible new way to vaccinate against malaria, one of the world's biggest killers.

Malaria kills up to 3 million people a year and sickens another 300 million. Creating a vaccine is crucial because the parasite has begun developing resistance to drugs used to treat malaria, and even mosquitos that spread the disease are withstanding pesticides.

But finding a malaria vaccine has proved exceptionally difficult, and testing in 1997 concluded the candidate long thought the best hope was actually worthless.

The reason most vaccine attempts have failed is that they focused on just one part of the malaria parasite's complex life cycle.

Now researchers from the U.S. Centers for Disease Control and Prevention and from India have created a multipronged vaccine designed to make the immune system fight the parasite at many stages: When the mosquito bite sends it into the body, when it invades the liver and when infection moves into the bloodstream.

The scientists immunized rabbits. The animals' immune system produced antibodies that prevented malaria parasites from invading liver cells and from replicating in the blood, the scientists reported Monday in Proceedings of the National Academy of Sciences.

Just because the vaccine stimulates a rabbit's immune system doesn't mean it would work in people, cautioned parasitologist Anthony Holder of London's National Institute for Medical Research.

The CDC hopes further testing in primates will prove promising enough to try the vaccine in people.