First, the bad news: urban malaria in Africa is becoming a major health problem and looks set to get worse.
The problem is growing along with Africa's cities. Urbanisation came relatively late to the continent, but the United Nations Environment Programme says Africa's urban growth is now the fastest in the world - nearly twice the global average. In 1960 there were no African cities with one million inhabitants: today there are 40. The UN predicts that the number of Africans living in towns and cities will increase 20 per cent within 15 years, to 800 million.
Malaria has long been a scourge, responsible for approximately 1 million deaths a year in Africa, making many millions more ill and acting as a brake on economic development.
And the situation may be even worse than was thought. New research published in the science journal Nature this week (10 March) calculates that more than 500,000 million people – nearly double previous estimates – were infected by the deadliest form of malaria in 2002.
Richard Feacham, executive director of the Global Fund to Fight AIDS, Tuberculosis and Malaria, said the results confirm the "gross underestimation" of malaria in Africa and Asia.
Now for the good news: urban malaria is controllable - if action is taken quickly.
"We are keen to get across that this is a potentially avertable problem," says Dr Martin Donnelly, a vector biologist at the Liverpool School.
"Urban malaria should be relatively easy to control," agrees Dr Guy Barnish, the projects co-ordinator of the School's Malaria Knowledge Programme. "There are more healthcare professionals in towns than in rural areas; it is easier for patients to get medicines, and hopefully you can tap into the private healthcare network"
In addition, he says, towns tend to have pockets of disease, which means areas and communities can be targeted, and insecticide-impregnated bednets are generally accepted more quickly in urban than in rural areas.
Even the pollution that can make cities so unpleasant to live in can be advantageous, because the Anopheles mosquito that carries the malaria parasite between people prefers relatively clean, if stagnant, water.
Until now, malaria has been seen as a rural disease, but that is changing, and last year a team of US and Swiss researchers estimated that 200 million Africans currently live in urban settings in which they are at risk of contracting the disease, with between 25 and 103 million malaria attacks occurring in towns every year.
Contributory factors include the rise of urban agriculture, as city dwellers increasingly grow vegetables for sale to the public. "Watering crops helps create suitable breeding conditions for malaria-carrying mosquitoes," warns Barnish.
Now that what the Liverpool School has described as "an old disease in a new environment" has been identified, the question is how to tackle it.
The School has helped spread the word: its malaria programme sponsored an international conference in South Africa last December. Action priorities were set out, and another meeting will be held in Marseilles, France, in September.
One area of action pinpointed by the meeting in South Africa is the need to move away from the policy of treating virtually all fevers as malaria, as generally happens in rural areas. To carry on this policy in towns, said the South Africa conference statement, "would likely result in a significant waste of resources through misdiagnosis and inappropriate treatment", because se fevers may be caused by other common infections apart from malaria.
Participants were drawing attention to the fact that misdiagnosis can mean that up to three-quarters of patients with a fever decide or are advised to take anti-malarial tablets although they do not have malaria. The tablets fail to treat whatever is the real cause of the fever, and are becoming more expensive as the malaria parasite develops resistance. This in turn makes poor people iller, poorer and puts more strain on already over-stretched health services. "Misdiagnosis probably contributes to a vicious cycle of increasing ill-health and deepening poverty," say Barnish and colleagues at the Liverpool School.
Instead, quick and simple blood tests could be used to confirm malaria cases. Testing equipment and staff costs money, but the expense has to be weighed against the money saved by not treating non-malaria fevers with increasingly expensive malaria drugs. A cost-benefit analysis of diagnosis and drug delivery in urban settings is required.
By Daniel Nelson