People resistant to malaria defend off disease-causing parasites in a way that scientists have puzzled over for decades.

Normally, parasites infect blood via mosquito bites and then the parasites steal cellular scaffolding from red blood cells that keep the oxygen-carrying cells intact.

Malaria-resistant people have mutated red blood cells that resist the parasite's ability to steal that necessary cellular scaffold, according to research published Thursday in the online edition of Science, uncovering a puzzle years in the making.

Decades ago, researchers noticed that certain populations in Africa showed resistance to malaria because of a mutated blood type, hemoglobin S, which can cause sickle cell anemia. Hemoglobin carries oxygen that red blood cells shuttle around the body. Another blood mutation, hemoglobin C, can also protect people from malaria that annually causes a million deaths globally.

(This study is) clearly a step forward in understanding why people who have these mutations have a slight advantage in symptoms of malaria, Nirbhay Kumar, study author and chairman of the department of tropical medicine at Tulane University in New Orleans, La.

The two mutated blood types also increase the risk for sickle cell anemia, an illness that causes pain throughout the body and eventually leads to organ failure.

Malaria is most common in sub-Saharan Africa, parts of Asia and the Americas where mosquitos are numerous.

The study points to new treatment avenues for clinical scientists to fight off Plasmodium falciparum, the parasite that causes malaria. Currently, the most common treatment for malaria is quinine, a medicine that doctors have used for centuries.

Understanding the underpinning mechanism (of malaria resistance) will provide novel opportunities for intervention, Michael Lanzer, a biologist at Heidelberg University Medical School in Germany and senior author, wrote in an email.

However, improved malaria treatments are still a long way off, Lanzer said.

That protein trafficking (the shuttling of parts needed to build cellular scaffolds) that is going on is important for parasite survival - that could lead to targets for drug design, but it's a long shot at this point, he said.

The pharmaceutical company GlaxoSmithKline is conducting clinical trials of a malaria vaccine in parts of Africa that they report is 65 percent effective, which Kumar, the biology professor at Tulane, said is better than nothing, but still a long way from a cure.

Marek Cyrklaff, molecular biologist at Heidelberg University and lead author on the paper said scientists still have a lot of work left to do in research on malaria and sickle cell diseases.

Indeed, understanding the mechanism of natural protection, such as this by hemoglobin mutations, would ideally ignite a bunch of follow up studies aiming on developing better treatments against malaria, he wrote in an email. But still, it is too early to speculate on final outcomes.

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