More than 40 per cent of the world's population is at risk of contracting malaria and more than half a billion people become ill with the infection every year. In Africa alone, at least a million people die each year from the disease, most of them young children.
For 30 years, we have been waiting for a vaccine, and Gordon Brown has pledged to support a global campaign to fund a new, experimental drug, expected to cost roughly £10 per immunisation. But we have the tools to control malaria now, halving its attacks on children under five and reducing all childhood deaths by 20 per cent. First, a mosquito net treated with a long-lasting insecticide costs less than £2. Second, effective antimalarial drugs (artemisinin-based combination treatments, or ACTs), costing less than 50p per child treated, can replace drugs such as chloroquine that no longer work.
Yet bodies such as the World Health Organisation and Roll Back Malaria have failed to make these solutions accessible to the people most in need. Fewer than 5 per cent of children sleep under an insecticide-treated bed net. Only a handful of African countries are implementing effective new-drug policies. Poor communities cannot afford to spend £10 per child; rural households already have to make almost impossible choices between putting food on the table or sending the children to school. Their governments depend largely on donor support for health-related spending. Yet even when support is offered, many are reluctant to commit to new but (to them) expensive control measures because these are usually promised for a few years only.
At this year's World Economic Forum, the actress Sharon Stone pledged $10,000 (£5,190) to buy bed nets for Tanzania, all treated with insecticide. In response, the superstar audience present raised $1m in 30 minutes. Now Tony Blair, better advised than Brown, has offered £45m for bed nets, and hopes he has set the lead for other G8 countries. But will it be enough? Is even the estimate of the UN Millennium Development Project - that we need bet-ween $1bn and $3bn a year - big enough?
Underestimating the needs of poor developing countries might be worse than doing nothing. A half-full dollar pot may produce sufficient resources for a couple of years only - and governments in malarious countries will see this as an all-too-familiar donor flash in the pan. They will have to choose who should get drugs and nets and who should go unprotected. Development partners will have to decide which countries get support. The choices will inevitably be political.
Africa and other malarial countries need investment in industrial and agricultural development if enough of the drugs and nets are to be produced. The US Institute of Medicine and Britain's Department for International Development have both proposed financial subsidies. Indeed, there is a strong economic case for providing the drugs and nets free of charge, given that malaria is such an enormous burden on poor countries. We are not talking about a bottomless pit into which donor money will disappear: this would be an extremely cost-effective approach to alleviating poverty and reducing deaths.
Let's find out what it will cost over ten years. Even if it is $10bn a year, it would still be a fraction of what we spend on the war on terror. Development involves many imponderables, but malaria is one of the few big problems we could fix. We have the tools and we know they work; we just have to make sure those in need get them.
Bob Snow is professor of tropical public health at the Kenyan Medical Research Institute in Nairobi and Oxford University. Nick White is professor of tropical medicine at Mahidol University, Bangkok, and Oxford University