The researchers showed that use of the nets can greatly reduce the number of mosquitoes that survive repeated encounters with protected humans. Also, by preventing the mosquitoes feeding on humans, the nets can divert them to feed on other mammals which do not host the malaria parasite, reducing the number of humans bitten and of mosquitoes carrying the parasite.

Dr Killeen and colleagues acknowledge that the financial implications of promoting net use by all age groups across malaria-endemic Africa will be significant, in the order of the total investments in health care in Africa excluding HIV.

"Fully subsidising enough nets to achieve 50% coverage would cost at least $1 billion, with ongoing recurrent costs of a similar magnitude," he says. "While we need to maximize subsidies for expanded target groups, we also need to ensure those receiving little or no subsidy can buy this essential public health commodity if they wish to."

Dr Killeen is keen to stress his support for the existing personal protection targets for vulnerable groups specified by the Millennium Development Goals and Roll Back Malaria: "The targets of the existing programmes are very worthy in themselves and we remain fully supportive of their continued prioritisation. We need to cover as many young children and pregnant women as possible without forgetting that even partial coverage of entire communities can provides greater and more equitable protection to everyone.

Co-author Patrick Kachur from the Centers for Disease Control and Prevention emphasizes that this is an achievable goal: A number of African countries are making progress towards the existing targets and should be supported to at
'"/>

Contact: Craig Brierley
c.brierley@wellcome.ac.uk
44-207-611-7329
Wellcome Trust
2-Jul-2007