He said fogging must be done at the right place at the right time; otherwise it would not bring the desired results in eliminating aedes, the primary vector for dengue and chikungunya.
"We assume where the aedes breeding grounds are when we carry out fogging but the mosquitoes may have already moved to other places. The pesticide is only effective within the radius of 200 metres," he told Bernama.
Dr Wan Yusoff said the use of trap lamps containing carbon dioxide had also been proven ineffective to control the aedes population.
He also said Malaysia could introduce attractants to trap mosquitoes but this method had yet to be proven effective in controlling the dengue outbreak.
Dr Wan Yusoff said checks should be carried out at potential mosquito breeding grounds like public toilets, construction sites, abandoned projects, parks and recreational areas, and clogged drains.
"Aedes could cling on to water containers like pales and flower pots even after they had dried up. They become active again when the containers are wet again.
"To remove them, we must scrub the pales and flower pots," he said, adding that, this explained how aegypti aedes from Africa was brought to Asia and albopictus aedes from Asia made its way to the United States. -- BERNAMA