Michael Nurok
Given that the number of people who die each year of malaria is equal to the cumulative number of Aids-related deaths in 15 years, one would expect at least equal amounts of money to be spent on research.
Yet less than 10% of the amount spent on international HIV research goes into malaria investigation.
The reason for this is quite simple. The scourge of HIV has infected the developed world’s psyche, whereas malaria is viewed by the West as a slightly exotic tropical disease limi-ted to poor countries.
This mindset creates lucrative markets for HIV and Aids medication where drug companies can easily recoup research and development expenses. As for malaria, health-care systems in countries decimated by it struggle to buy the most basic drugs.
This situation is compounded by the increase in resistance to almost all anti-malarial drugs. In an effort to address this growing crisis the World Health Organisation (WHO) has been looking for new medications.
A breakthrough has come in the form of a plant used by Chinese traditional healers. For almost 2 000 years, Artemisia annua or Qinghaosu has been made into a tea and given to patients with high fevers – one of the most common symptoms of malaria. In the 1970s, the Chinese state developed the Qinghaosu extract, artemisin, as a malaria treatment.
In the body, malaria parasites undergo a development cycle that culminates in sexual forms of the organisms. Parasites in this sexual phase are ingested from the blood when a new mosquito bites an infected patient, completing the transmission cycle.
Artemisin produces toxic substances, called “free radicals”, which cause infected red blood cells to burst, killing the parasites.
Artemisin is also effective against the sexual stage of malarial infection, thereby preventing further spread of the disease to new mosquitoes.
Conventional malaria medication only works against specific phases of the malaria cycle.
Given its multi-phase action and the fact that it has been used effectively in China for centuries, researchers are hoping artemisin won’t encounter the conventionally high degree of drug resistance.
Artemisin has been shown to be neurotoxic to animals, but this problem only occurs at doses 10 times higher than used for humans and with repeated exposure to the drug.
Fortunately, such brain changes are thought to be reversible.
Most clinicians agree that the benefit of a potentially life-saving treatment outweighs the small risk of neurological complications.
The WHO is particularly interested in the artemisin derivative, artesunate, thought to possess one of the lowest risks of neurotoxicity while retaining powerful anti-malarial properties. A Swiss generic manufacturer is currently making Artesunate at low cost for the WHO.
Clinical trials comparing artesunate with the current gold standard treatment, quinine, are currently under way in northern KwaZulu-Natal, Malawi, Thailand and Brazil.
Researchers are being particularly vigilant about monitoring for neurological side effects. Preliminary results have been encouraging and local study co-ordinator Dr Karen Barnes, of the University of Cape Town, hopes Artesunate will be submitted for United States Food and Drug Administration approval by the end of the year.
Unwittingly, artemisin has been used in Southern Africa for decades. Local traditional healers use the plant Artemisia afra as a treatment for malaria, fever and flu.
However, several researchers at different sites have confirmed only low levels of artemisin in Artemisia afra, so it is unlikely the plant would make an effective anti- malarial treatment.