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.