Bednets are not enough

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Eliminating malaria, especially from its hotspots in Africa, will be impossible without new types of intervention, a newly published model has confirmed.

To eliminate malaria in Africa, current interventions would need to reach far more people than health and transport infrastructures permit, according to Prof Azra Ghani,  an infectious disease epidemiologist, and colleagues at Imperial College, London.

The team modelled how current and future anti-malaria interventions might affect the mosquito that carries the most dangerous malaria parasite, Plasmodium falciparum. Today's tools include insecticide-treated bednets, indoor spraying with insecticides and the latest drug (artemisinin). Future tools include vaccination.

The model revealed that, in areas with low to moderate malaria transmission, increasing interventions so they cover 80 per cent of the people — which is considered an achievable target — could cut infection with the parasite to one per cent of the human population — a level considered to be sufficiently low that control methods can keep the disease from spreading.

But their model also clearly showed that in areas of high malaria transmission, reducing infection to a similar level would require unfeasibly widespread interventions, especially given the poor infrastructure.

There is renewed enthusiasm to rid the world of malaria, rather than just control the disease. In 2008 the WHO launched the Global Malaria Action Plan, which has led to initiatives such as the Malaria Eradication Research Agenda (malERA).

And on World Malaria Day this year (24 April), the US Centers for Disease Control and Prevention promised to try to eliminate the disease by making malaria interventions universally available. Meanwhile funding for malaria nearly doubled to US$1.7 billion between 2006 and 2009.

"Our model can help planners evaluate the likely impact of combining interventions," said Ghani whose work is published in the August edition of PLoS Medicine. "It can help them to prioritise where resources are limited."

The new results confirm previous malaria models, said Dave Smith, biologist at the Emerging Pathogens Institute, University of Florida, United States.

The added value of the new model, he said, is in simulating malaria transmission between individuals in settings across the continent, thus being simultaneously detailed and far-reaching: "which is not an easy thing to do".

Geoff Targett, of the UK-based London School of Hygiene and Tropical Medicine, told SciDev.Net that the model was particularly valuable because it managed to include the variability in transmission across the continent.

Creating effective vaccines, said Targett, especially those that block transmission of the parasite rather than preventing disease after infection, "is likely to be the one major development that will ensure that control, and particularly elimination, become feasible across Africa".

Link to full article in PLoS