Malaria parasites are able to adapt their growth rate to render anti-malarial drugs useless, according to new research by Australian scientists.

More than 200 million people are infected annually with the malaria parasite Plasmodium falciparum, with around 800,000 children dying every year of the mosquito-borne disease.

Researchers at La Trobe University have uncovered new detail on how the parasite reacts to anti-malarial drugs and adapts to neutralise their effects, paving the way for better designed drugs in future.

The study, published in the scientific journal Proceedings of the National Academy of Science, examined a common malaria treatment based on a wormwood extract called artemisinin.

“Recent reports of decreased clinical effectiveness of artemisinin-based drugs are extremely concerning,” said lead researcher Professor Leann Tilley from the Department of Biochemistry at La Trobe.

“It is therefore critical to understand the way artemisinin works so that we can overcome the pathogen’s resistance to this drug.”

Professor Tilley’s research team observed that artemisinin works by reacting with an iron-rich chemical called haem that is produced as the pathogen consumes the protein haemoglobin from within a human’s red blood cells.

If the levels of haem iron are low, artemisinin is less effective – so all the parasite has to do is cut back on its consumption of haemoglobin, thereby cutting down the production of haem.

“Decreasing the production of this iron renders the parasites resistant to artemisinin,’ Professor Tilley said.

"We have also shown that the parasite can slow its growth and reduce its haemoglobin uptake rate in response to artemisinin treatment. This helps it avoid the toxic effects of artemisinin.”

Professor Tilley said the research may lead to to new ways of adapting antimalarial drugs to overcome drug resistance.