The UN agency said it would ask the 37 countries and territories that make up its Western Pacific section to endorse a regional strategy for dealing with the mosquito-borne virus, which it deems among 40 emerging diseases of global importance.

A dengue pandemic swept across the region between 1991 and 2004, peaking with 350,000 cases in 1998, the WHO said.

Of the 2.5 billion people at risk globally, 1.8 billion live in the Western Pacific.

Ninety-eight percent of all dengue cases -- and 99 percent of all dengue deaths -- in the region between 2001 and 2004 were accounted for by Vietnam, Malaysia, the Philippines, Cambodia, Laos, Singapore, French Polynesia, Fiji, New Caledonia and China.

The WHO said in discussion papers at a regional committee meeting in Manila that dengue "has greatly expanded over the last three decades" owing to changes in weather patterns that expanded the habitat of the Aedes aegypti mosquito which carries the virus.

"Human practices such as rainwater harvesting and inappropriate disposal of used tyres, plastic containers and metal cans have created new opportunities for vector breeding."

Other key factors were migration, demographic changes, and rapid growth in urban areas.

"Dengue is a neglected disease that gains attention during an epidemic," it said. "Many Asia-Pacific countries lack adequate resources and have limited response capacities" against the virus.

In some cases there are no national programmes, and if there were, scant resources were spent, and mostly on "insecticide sprays and chemical larvicides which have little impact on controlling the epidemic".

The WHO called for "new and improved diagnostic, preventive and therapeutic tools," saying dengue deaths can be cut to one percent or less if the disease is diagnosed early and treated appropriately.