PUTRAJAYA (THE STAR/ASIA NEWS NETWORK) - Malaysia's Health Ministry is trying outdoor spraying of a deltamethrin-based insecticide to kill Aedes mosquitoes in view of the record high number of dengue fever cases recently.

Currently used to control pests in agriculture and gardens as well as on pets, deltamethrin is a synthetic compound that gives a broad-spectrum effect, meaning that most species of mosquitoes and other insects will also be affected.

Health Minister Datuk Seri Dr S. Subramaniam said the number of dengue cases - more than 100,000 with 215 deaths last year - was the highest the country had ever faced. More dengue patients also had their brain and liver affected by the virus.

"We take the higher number of deaths seriously," he said at a press conference on Wednesday.

He said the ministry had started the residual spraying since Feb 11 in four Selangor districts with a high number of dengue cases - Petaling, Hulu Langat, Gombak and Klang.

"The effectiveness of the spray will be assessed over two to three months and, if proven to be effective, we will expand the use of the spray to other areas," he said, giving an assurance that the active ingredient was not harmful to humans.

Dr Subramaniam said the active ingredient was expected to last for three months in the field, and mosquitoes coming into contact with the sprayed surface would die.

He also reiterated the importance of doctors diagnosing dengue early, saying that two companies had agreed to lower the cost of the rapid test kit by 40 per cent.