Seattle researchers test potential malaria vaccine on 10 volunteers

Would you be willing to be bitten by 200 mosquitoes? What if those same mosquitoes were infected? Ten volunteers bared their arms in Seattle Wednesday, all in the name of developing a vaccine for malaria. Lori Matsukawa reports.

SEATTLE - They were restless and absolutely ravenous.

For 200 malaria-infected mosquitoes, this was meal time on Dr. Rafael Hernandez's forearm.

"You or I are used to getting one or two or, through camping, maybe 20 mosquito bites at once, not 200 in one spot," he said.

The sensation tickled at first, then it itched and then it started to hurt, as a cloud of mosquitoes feasted for a full 10 minutes on a rectangular patch of his skin.

Dr. Hernandez, a pediatrician at Seattle Children's, was one of 10 volunteers to bare their arms Wednesday morning in an early test of a vaccine against malaria.

Researcher Stefan Kappe of Seattle Biomed has been working for a decade to reach this milestone. He said there have been plenty of ups and downs.

"Right now we're on the 'up' that we have a very promising strain that is fully attenuated, but the real litmus test for this is the study in humans," he said.

The weakened strain was developed by removing genes in the mosquito parasite that causes malaria.

That in itself was a huge feat.

"Remember that the parasite is teeny, it's about one-hundredths of a millimeter," he said. "Just imagine, this is (now) a parasite that is alive that can infect you initially but then it cannot cause amplification of the infection and cannot make you sick."

Or at least that is the hope. The verdict won't be in for about a week, which is how long it takes for malaria symptoms to develop following exposure.

"What we are evaluating here is if this parasite can absolutely cause no infection. If that is the case we are all very happy and we can move forward potentially with using that strain for intervention such as a vaccine."

Dr. Kappe cautions, however, that this is still early days in the research. Realistically, a commercial vaccine is about a decade away.

As for Dr. Hernandez and the nine other volunteers, all said they'd be willing to go through the experience again.

The Department of Defense is funding the research.


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