Singapore, October 1:

The world is seeing an explosion in dengue infections as the virus-carrying Aedes mosquito adapts to city environments and grows immune to traditional methods of population control, a panel of experts in Singapore said today. “It’s a global pandemic,” said Dr Duane Gubler, director of the Asia-Pacific Institute of Tropical Diseases in Hawaii. “It’s quite clear that the disease has evolved. There just is more dengue in the world.” All across Asia, governments are scrambling to contain the virus, which is only carried by the Aedew mosquito.

Singapore has already recorded more than 11,000 cases this year, exceeding the previous record of 9,459 set in 2004. Neighbouring Malaysia has reported close to 28,000 human infections — more than 25 per cent compared to a year ago. And the Philippines and Thailand are also battling a rash of infections. Dengue-armed “guerrilla” mosquitos were the world’s new enemy, said Dr Paul Reiter, an infectious diseases expert from the Pasteur Institute in France.

Both Reiter and Gubler were among seven experts invited by Singapore’s Ministry of Health to investigate the city-state’s current spike in infections. The panel said the increase in cases could be because the virus had muted into a new strain “with greater epidemic potential.” The US Centers for Disease Control and Prevention considers dengue the “most important mosquito-borne viral disease affecting humans” this year — ahead of malaria and encephalitis — with an estimated 2.5 billion people at risk worldwide. Once confined to the jungles of the tropics, the mosquitos were now entering and adapting to urban areas, the panel said.

“It’s a mosquito that used to breed in tree holes, but it has adapted to the human environment,” said Reiter. Reiter also said Singapore’s success in cutting the mosquito population had left the population with a lower resilience to infection. Methods like mass aerosol spraying, or fogging, used to bring down mosquito numbers for decades, may now be less effective than before, says Gubler as they were dependent on external factor such as wind direction and concentration of the chemical mix and because the mosquitos were developing immunity.