South African scientists have made a crucial breakthrough in malaria research that will enable more effective drugs to be developed to treat the parasite-based infection that has plagued humans for centuries.
The breakthrough is based on identifying how the malaria parasite handles the iron in humans’ red blood cells, according to Dr Giovanni Hearne of Wits University’s School of Physics.
Medical researchers have been battling to combat the disease, described by Hippocrates as far back as 4 BC, because of the parasite’s complex life-cycle.
“The parasite feeds on haemoglobin in red blood cells and destroys its oxygen-carrying capacity,” says Dr Hearne. “Part of the haemoglobin called haem is potentially toxic to the parasite.”
“Our breakthrough centres on the discovery that the parasite manages to disable the toxic part called haem, by converting it to another substance called haemozoin.
“New drugs can now be designed to block this detoxification pathway so that the haem remains deadly to the parasite,” said Hearne, who was part of a team of physicists, chemists, pharmacologists and microscopists headed by Dr Tim Egan of the University of Cape Town that made the discovery.
The anti-malarial drug chloroquine probably worked by blocking this detoxification pathway, but “no one really knew how it worked”, said Dr Egan.
“In the last ten years there has been growing evidence that chloroquine blocks haemozoin formation, but we did not know whether a significant fraction of the haem is actually incorporated into haemozoin,” added Dr Egan. “This study has for the first time demonstrated that this is the case.”
Chloroquine is no longer effective because of drug resistance but now new drugs that work in a similar way can be developed, said Egan, who has been working on the study for the past nine years.
Malaria is transmitted to humans through the bite of an infected female anopheles mosquito. It is a huge problem world-wide, particularly in Africa. Every year, it kills up to three million people, mainly babies, and causes up to 200 million infections, according to the World Health Organisation.
The Minister of Health recently told parliament that malaria cost southern Africa an estimated R5,9-billion and South Africa more than R124-million in 1998.