Malaria parasite ‘could develop resistance to key drug’

Sweet wormwood: source of artemisinin Copyright: Scott Bauer/US Agricultural Research Service

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Malaria could easily become resistant to artemisinins, the latest and most effective drugs against the parasite, researchers warned this week.

The team’s research, published online on 5 June by Nature Structural and Molecular Biology, shows how Plasmodium falciparum, the parasite that causes malaria in humans, could mutate and become immune to the drugs.

Sanjeev Krishna at St George’s Hospital Medical School in London, United Kingdom, who led the research, and his team suggested in 2003 that artemisinins work by blocking a parasite protein that carries calcium in and out of cells.

As a result, said the researchers, calcium builds up, killing the cells. At the time, their findings were received with some scepticism.

Now, the same team has published further research supporting this theory. They add that a small change in the calcium carrying protein could make the parasite resistant to the drugs.

The scientists used laboratory techniques to change a small detail of the protein’s structure and found that artemisinins were no longer able to block it.

Krishna told SciDev.Net that the international scientific community should actively begin to look for signs of resistance in wild forms of malaria now, rather than “play catch-up”.

“History has shown us that resistance has developed to all other malaria drugs; it would be negligent not to take our experience into account.”

He adds that although it is difficult to say when P. falciparum might become resistant to artemisinins, the likelihood of this happening increases as more and more people use the drugs.

Krishna says sites should be monitored across Africa and other places where artemisinin-based therapies are being provided by institutions such as the World Health Organization (WHO).

He added that in addition scientists should try to “design their way out of this [problem]”.

For example, the next generation of artemisinin-based drugs could be designed to affect the malaria parasite in a different way.

Artemisinin became the WHO ‘drug of choice’ against malaria in 2001.

Since then significant efforts have been made to increase its use worldwide.

Reference: Nature Structural and Molecular Biology 2005 (online), DOI: 10.1038/nsmb947