A recent research shows that, mosquitoes that transmit dengue and other viruses have evolved growing resistance to insecticides in parts of Asia.
Health authorities have shown serious concern, but the scale of the problem was not well understood.
They found some mosquito strains had 1,000-fold resistance, compared to the 100-fold seen previously.
Dengue can cause hemorrhagic fever and infects an estimated 100 to 400 million people a year, although over 80 percent of cases are mild or asymptomatic, according to the World Health Organization.
Several dengue vaccines have been developed, and researchers have also used some bacteria that sterilises mosquitoes to tackle the virus.
But neither option is yet close to eradicating dengue, and Aedes aegypti mosquitoes carry other diseases, including zika and yellow fever.
