African medicinal plants against malaria

1. African medicinal plants against malaria Dr Merlin Willcox, RITAM (Research Initiative on Traditional Antimalarial Methods)

2. Meeting Objectives • To share information • To develop a collaborative action programme for Africa-wide production and distribution of appropriate herbal antimalarials

3. The economics of malaria • 2-5 billion febrile episodes a year resembling malaria • 500 million cases of malaria • 1.1 million deaths • 90% of deaths are in African children • 58% of deaths in poorest 20% of population

4. Economics of malaria (2) • Up to 75% use traditional herbal medicine as first line treatment • Adult course of ACT = $2.4, may reduce to $1 • Diagnostic test = $1 • Big pharma is not investing in malaria

5. What is your main objective? • To reduce malaria mortality and morbidity? • To create jobs and businesses?

6. What is your market? • Poor people in remote areas with no access to modern health care? • People who already have access to modern pharmaceuticals? • Public health programmes? • Herbal prophylactics for ex-pats?

7. What is an “appropriate” herbal antimalarial? • Standardised phytomedicine or home-grown plants? • Cheaper than ACTs? • Parasite clearance or adequate clinical response? • Efficacy or cost-effectiveness? • Depends on context….

8. Types of R&D: Different products, endpoints & methodologies • Bioprospecting for active molecules: new leads for conventional drug development • Phytomedicines: standardised herbal extracts. • Traditional medicine:prepared according totraditional formulations

9. The competitive advantage of herbal antimalarials • Affordable • Available • Sustainable • Reach the parts that modern drugs don’t reach…

10. Ways of using plants against malaria • Insect repellents • Vector Control • Prophylaxis • Treatment

11. The limitations of traditional medicine • There is little clinical data on safety and efficacy • Content of active compounds in plants is variable • There is no consensus on what plants, preparations and dosages to use • These are all remediable, through research…

12. RITAM • Research Initiative on Traditional Anti-Malarial Methods • Founded in 1999 by GIFTS of Health, with support from TDR, Rockerfeller • www.gifts-ritam.org

14. Specialist Groups • Policy, Advocacy and Funding • Networking, publications, funding, ethics, intellectual property rights • Preclinical • Database, guidelines • Clinical Development • Database, systematic reviews, guidelines • Insect repellence and vector control • Database, systematic reviews, guidelines • Artemisia annua Task Force • Overview of literature • Clinical trials planned

15. The bottom line • Herbal insect repellents: some evidence • Herbal insecticides: some evidence • Herbal treatments: controversial, some clinical evidence • Herbal prophylactics: NO clinical evidence

16. Chicken or egg? • “Show us the evidence that it works” • Who will pay to generate the evidence?

17. Herbal treatments • No herbal treatments have yet been described to be as efficacious as ACTs for parasite clearance • Several herbal treatments could potentially be more cost-effective than ACTs in certain contexts

18. Where could herbal antimalarials be more cost-effective? • Home management • Presumptive malaria • Semi-immune patients (Adults, children > 5 years old)

19. When is it unethical to recommend herbal antimalarials? • [on current evidence] • Non-immune patients • Children aged <5 • Pregnant women • ? If a proven treatment is locally available and affordable to the patient?

20. The Artemisia annua debate • Jansen, 2006: “I believe that the herbal tea approach to artemisinin as a therapy for malaria is totally misleading and should be forgotten as quickly as possible”. • Anamed: promoting A. annua cultivation and use as a tea. • RITAM response: Need more research

21. Approaches to A. annua • Grow the plant as a cash crop, to sell to pharmaceutical companies, which will make ACTs • Grow the plant for local distribution as tea bags • Grow the plant in village “green pharmacies” where no other healthcare is available.

22. Problems with A. annua tea • High level of recrudescence at doses tested • Optimal method of preparation and dosage not yet defined • Variability in artemisinin content

23. Potential of A. annua tea • Cheaper than ACTs • Could it be more cost-effective in certain situations, e.g. for home treatment of malaria? • Could it be more effective if combined with other herbal antimalarials?

24. Prophylaxis • Many herbal prophylactic preparations are used • Almost none have been investigated • Some Hausa tribes have lower than expected incidence of malaria (Etkin & Ross, 1991) • In the malaria season, they eat plants with antimalarial properties

25. Neem as a repellent • Neem oil on cardboard mats is as effective as synthetic repellents • Costs $0.50 per room per year (cf. $25 for synthetic repellents) • Also effective topically (2% in coconut oil) for 12 hours • Neem oil is larvicidal (LC50 = 3-8ppm)

26. Phytolacca dodecandra • Widespread tropical plant • Crushed, powdered berries used as soap and as pesticide • Effective at killing schistosomiasis transmitting snails • Effective at killing mosquito larvae

28. Possible roles for medicinal plants • Vector control and repellence • Prophylaxis • Treatment, especially: • Presumptive malaria • Home management • Adults and children >5

29. Conclusions • Herbal antimalarials have huge potential • More research IS needed (esp clinical and public health) • But who will pay for it? • Need to go beyond laboratory studies in order to deliver a health impact.

30. www.gifts-ritam.org