Does it work? Can artemisia help to cure malaria?
BACKGROUND:Discussions about coalitions and collaborations sometimes ring a little hollow. But there are success stories that remind us that powerful organisations sometimes combine forces to help people in meaningful ways. The story of an inconspicuous herb that grows almost anywhere is a reminder of the healing potential within some plants.
Malaria continues to be a major health problem. About 250 million people are infected each year, resulting in almost one million deaths. Control of malaria requires a multifaceted approach that includes bed netting, land drainage and insecticides. Effective drugs have a role also, but are limited by resistance among parasites. The World Health Organisation (WHO) has recently changed its first-line treatment to drugs based on artemisinin, a compound found in the herb Artemisia annua.
As with other major advances with infectious diseases, this discovery was triggered by war. Malaria killed many soldiers during the Vietnam War, leading North Vietnamese leaders to appeal to China for help. New drug combinations were found, and a long-term search for new treatments initiated. This included an examination of herbs used in traditional Chinese medicine. The most promising one was a tea made by boiling Artemisia annua. This plant is known in the West as sweet or annual wormwood, or sweet Annie.
Chinese researchers found that the teas varied widely in their potency. In 1972, an extract made with cold ether was found to be highly effective against malaria in the lab and in patients. The active ingredient was isolated and called qinghaosu or artemisinin. The chemical structure was determined and scientists modified it to produce other effective antimalarial drugs, including artemether and artesunate.
EVIDENCE FROM STUDIES
The first clinical trial of artemisinin was conducted in 1979 with more than 2,000 malaria patients in China. It reported that all patients were cured, a remarkable finding. Dozens of other studies have since been conducted. Cochrane systematic reviews have found that various artemisinin-derived drugs are more effective and safer than other drugs used for various types of malaria.
While artemisinin rapidly removes malaria symptoms, they often reappear within a few weeks. Various combinations of artemisinin-related drugs were tested. In 1994, the first collaborative project between Chinese researchers and western scientists (from the company today called Novartis) was initiated. This has led to an effective combination product that works in six doses.
The success of combining related drugs has led to renewed interest in using the plant material itself. This could allow people to grow their own treatments rather than purchasing pharmaceuticals. Clinical trials have found that Artemisia annua remedies quickly reduce malaria symptoms.
However, the blood levels of artemisinin achieved were much lower than with pharmaceutical preparations and malaria symptoms often reappeared within a few weeks. For these reasons, these herbal remedies are not recommended.
The herb Artemisia annua is well tolerated, with few adverse effects. Trials of the semi-synthetic derivatives have also found only mild adverse effects. At suitable dosage, some of these products have been found safe to use in children and late pregnancy.
Pharmaceutical products made from artemisinin and its related compounds have quickly become important weapons in the fight against malaria. Specific combination products are now part of the WHO Essential Drugs List. This development has required international co-operation between experts in herbal remedies and pharmaceutical developers.
Although Artemisia annua is available in a growing number of herbal remedies and teas, the WHO discourages their use. The amount of active ingredient in these products is insufficient to provide long-term benefits. Using insufficient doses may even facilitate the development of resistance in malaria parasites.
In this particular case, combining traditional knowledge of herbal remedies with modern pharmaceutical research has led to better treatments being developed for malaria.
Dónal OMathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University