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Researchers Advance Toward Effective Malaria Vaccine


Malaria kills millions of people annually, many of them children. So far, the disease has defied scientists who have tried to create a vaccine against it. But now, there are several vaccines in different testing phases.

Scientists have theorized for a long time that a successful malaria vaccine was possible, but making it has proven to be a more difficult proposition than they thought. Malaria researcher Christian Loucq says in part that's because malaria is a very complex disease.

"It has different phases in the human body... when the mosquito bites, [the malaria parasite] goes to the liver. It stays in the liver for some time and then infects the blood, and then it is going to develop at a very high speed and induce all of the symptoms of disease, the fever and all that we know is malaria."

Loucq directs the Malaria Vaccine Initiative for the non-governmental health research organization PATH. Currently, the MVI has two different vaccines at different levels of the testing process.

One vaccine is made from a weakened strain of malaria. With other disease-causing microorganisms, this approach prompts the body to mount an immune defense, so it recognizes the stronger form of the disease when a person gets infected and can fight off the infection. But Loucq says, with malaria, that approach is more complicated. The vaccine using this technique is only now being tested for safety on volunteers.

"We are going to inoculate 104 people [with the vaccine], and we're going to give them four injections. After some time, we're going to have them bitten by mosquitoes carrying an effective form of the bug. It is, in fact, a mosquito that can give the disease."

Loucq says once he and his colleagues determine that this vaccine is safe for people, they will proceed with further testing. They should know the answer to the safety question by the end of 2009.

For the second vaccine, scientists purified part of the malaria parasite and injected that into subjects. Loucq says, theoretically, people receiving this vaccine should create immunity to the disease. Testing for this vaccine is much further along. The researchers already know that it's safe... and effective.

"We have shown more than 50 percent protection, which is a tremendous achievement in the field of malaria. And now we are going to test those data and [see] if the vaccine works in a much larger population - 16,000 children and infants in 11 sites and seven countries across Africa. And that is going to go on for up to three years, to understand how this vaccine works over a longer period of time, as well."

Loucq says there are many ways to control malaria now, including bed nets, insecticides and medications. But he says the disease won't really be eradicated until there's an effective vaccine against it. And, he says, some day, that will be developed.

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