African medicinal plants against malaria

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African medicinal plants against malaria

• Dr Merlin Willcox, RITAM
• (Research Initiative on Traditional Antimalarial
  Methods)

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Meeting Objectives

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

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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

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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

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What is your main objective?

• To reduce malaria mortality and morbidity?
• To create jobs and businesses?

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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?

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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.

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Types of RD Different products, endpoints
methodologies

• Bioprospecting for active molecules new leads
  for conventional drug development
• Phytomedicines standardised herbal extracts.
• Traditional medicine prepared according to
  traditional formulations

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The competitive advantage of herbal antimalarials

• Affordable
• Available
• Sustainable
• Reach the parts that modern drugs dont reach

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Ways of using plants against malaria

• Insect repellents
• Vector Control
• Prophylaxis
• Treatment

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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

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RITAM

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

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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

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The bottom line

• Herbal insect repellents some evidence
• Herbal insecticides some evidence
• Herbal treatments controversial, some clinical
  evidence
• Herbal prophylactics NO clinical evidence

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Chicken or egg?

• Show us the evidence that it works
• Who will pay to generate the evidence?

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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

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Where could herbal antimalarials be more
cost-effective?

• Home management
• Presumptive malaria
• Semi-immune patients (Adults, children gt 5 years
  old)

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When is it unethical to recommend herbal
antimalarials?

• on current evidence
• Non-immune patients
• Children aged lt5
• Pregnant women
• ? If a proven treatment is locally available and
  affordable to the patient?

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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

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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.

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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

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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?

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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

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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)

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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

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Possible roles for medicinal plants

• Vector control and repellence
• Prophylaxis
• Treatment, especially
• Presumptive malaria
• Home management
• Adults and children gt5

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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.

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www.gifts-ritam.org