The Health Ministry will study the effectiveness of the new method of fogging - 'Outdoor Residual Spray' or ORS in its effort to reduce dengue cases nationwide, said Health Deputy Minister, Datuk Seri Dr Hilmi Yahaya.

He said the ORS method was first introduced in Selangor since early February to overcome the increase of dengue cases in the state.

"Selangor recorded the highest number of dengue cases compared to other states. Therefore, the ministry will use the ORS method as the new way of curbing the Aedes mosquitoes breeding ground apart from the conventional fogging method used.

"Usually, fogging is spraying smoke in the air around the area identified as dengue hotspots but by using the ORS method, it will be sprayed on the wall of the premises and mosquitoes will die upon contact with ORS, he said.

Hilmi told this to reporters after checking for dengue breeding grounds with the Penang Health Department enforcement team at several construction sites around Bandar Perda, here on Friday.

He said the effectiveness of the ORS in Selangor would only be known in three months.

"If the results show it is an effective method in destroying Aedes mosquitoes, then the ministry will widen its usage to all states as dengue is a serious issue and needs to be addressed with urgency," he said.

Meanwhile, he said for the period of January until yesterday, a total of 25,459 dengue cases wer recorded nationwide compared to 17,677 cases in the same period last year.

Hilmi said 65 deaths were reported in that perios against 33 death for the same period last year.Selangor posted the highest dengue cases with 14,979 cases and 37 deaths.