How close are scientists to a vaccine for malaria?

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Mats Wahlgren, Professor at the Department of Microbiology, Cell and Tumor Biology, Karolinska Institutet about vaccine for malaria.

"A vaccine that has been tested on young children in Africa has halved the risk of developing severe malarial symptoms. This is a vaccine that prevents the parasite from entering the body and that is currently being tested in several African countries. The Gates Foundation is investing huge resources on this but the outcome is very uncertain, as so far only a weak level of protection has been observed against the disease itself. We therefore need alternative approaches to the development of a malaria vaccine.

"At Karolinska Institutet we are developing a vaccine that protects against the lethal stages of the disease. During part of its life-cycle, the single-cell parasite responsible for severe malaria, plasmodium falciparum, penetrates the red blood cells. Once inside, it starts to produce proteins that cause the blood vessels to clog up, a stage of the disease that leads to potentially life-threatening anoxia. Our vaccine consists of the `sticky´ protein, which enables the body to develop a resistance to it. Lab and animal trials show that the vaccine prevents the blood cells from clogging up the blood vessels, so that the infected cells can be led to the spleen and ultimately destroyed. There are, however, several strains of the parasite, and our vaccine has shown to be effective against many but not all of them. We are now analysing this, and improving our vaccines by introducing add-ons."

Facts about malaria

Affects: Around 300 million people contract the disease every year. Between one and two million die, mainly young children and pregnant women.

Caused by: A type of single-cell parasite (protozoa), which is spread by mosquitoes.

Problem: What is the current status of research? More and more protozoa are developing a resistance to the medicines that exist, and the mosquitoes to the available pesticides. One danger is that the disease spreads higher up the mountains, further south and further north because of global warming.

Text: Cecilia Odlind. Published in "Medicinsk Vetenskap" nr 1 2010.