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[NEW DELHI] Communities and their religious and political leaders must join the battle against dengue fever in Asia, say the authors of a study on how the disease could be contained.
The public health response to dengue should extend beyond a "one size fits all" approach such as a reliance on insecticide fogging, they report, adding that "a change of paradigm in vector management seems essential".
The study, carried out in six Asian cities, sought out the breeding sites of dengue-carrying mosquitoes and considered how communities could limit the water sources that sustain the insects.
Dengue is now the most rapidly spreading mosquito-borne viral disease in the world. In the absence of an effective drug or vaccine, health authorities rely on controlling the vectors to reduce disease transmission.
Published in this month’s Bulletin of the World Health Organization, the study surveyed a range of public and private spaces in urban areas to unpick the biological, ecological and social determinants of Aedes aegypti, the dengue mosquito vector.
They found that most mosquito pupae — referring to the resting or non-feeding stage in the mosquito life cycle, lasting about two days — were produced in outdoor containers of rainwater, followed by indoor containers of rainwater and, thirdly, those containing tap water.
"This suggests that the vector prefers untreated water and reconfirms reports that rainwater-filled containers appeal to A. aegypti for breeding, even if they are indoors," the authors say.
Unused and unprotected containers in shaded areas — which contained the most pupae — need special attention, they add.
But covering water containers is effective against vector breeding only with the use of certain synthetic containers that can be sealed or by treatment with insecticides.
Further, densely populated areas offer more opportunities for mosquitoes to feed on people’s blood, so control programmes in endemic areas should target crowded living conditions, the study says.
It adds further evidence to support the WHO’s updated guidelines for dengue management, published in December 2009. These include advocacy and social mobilisation; targeted strategies based on thorough understanding of mosquito ecology and attitudes of residents to water containers; and coordination between health and other sectors.
"Integrated vector management and partnership among stakeholders [local inhabitants in cities, towns and villages] are required," Axel Kroeger, professor at the WHO special programme for research and training in tropical diseases and one of the study authors, told SciDev.Net.
"The current control systems have to be re-organised from a paternalistic approach — ‘we do everything for you’ — to a participatory approach defining the different roles for the different actors," he said.