Trees of life

I believe that the next generation of medicines should come from Africa, which is why the domestication of these species is so important.

"When I get malaria, I don't go to the chemist," says Najma Dharani, a botanist at the World Agroforestry Centre and Nairobi's Kenyatta University. "I take a concoction made from Zanthoxylum bark, and it always works well."

Dharani is the lead author of Common Antimalarial Trees and Shrubs in East Africa, which describes the findings of a research project involving the World Agroforestry Centre, the Kenya Medical Research Institute and traditional medical practitioners. The book focuses on the ecology, use and active ingredients of 22 plants used in the treatment of malaria. "Pastoralists like those in Turkana and Samburu have been using indigenous plants as medicines for hundreds of years, and they continue to do so," says Dharani. This is partly because they have no choice; few have access to clinics and modern medicines.

Caused by the Plasmodium parasite, malaria has a devastating impact on communities throughout sub- Saharan Africa. It is the leading cause of death in children under five, and of the infectious diseases in Africa only HIV/AIDS kills more people. It is estimated that just 8% of children under five with malaria in Kenya in 2007 were treated with modern artemisininbased combination therapies. This is one reason why traditional remedies are so important.

The book is aimed at two distinct audiences. It informs scientists about key gaps in research. To give just one example, Zanthoxylum species contain substances that are reported to show strong anti-malarial activity. According to Dharani, they also have the potential to treat other diseases, yet relatively little research has been done on this group of trees.

The book also provides guidance to local communities."We found that some people are using species to cure malaria which don't show strong anti-plasmodial activity, so we recommend that they use those species which do." Dharani and her colleagues are training local communities how to establish nurseries and encouraging them to plant antimalarial trees on their farmland. "I believe that the next generation of medicines should come from Africa, which is why the domestication of these species is so important," she says. The Lancet, one of the world's leading medical journals, was one of many publications to run features about the book.

Dharani N, Rukunga G, Yenesew A, Mbora A, Mwaura L, Dawson I and Jamnadass R. 2010. Common antimalarial trees and shrubs in East Africa. Nairobi: World Agroforestry Centre.