THE National Environment Agency (NEA) is stepping up checks and fogging and misting operations to stop the spread of malaria.

About 50 officers are doing daily checks of breeding sites as well as chemical fogging to kill adult mosquitoes and BTi mistings to kill the larvae.

These daily operations will last for at least three weeks or until no more cases are reported.

So far, at least 15 cases of malaria have been reported in the last five weeks.

None of the patients has travelled recently so they could not have brought the disease in from another country - making this the largest local outbreak in years.

Fourteen cases involve foreign workers while one case is a full-time national serviceman.

Foreign worker dormitories in the two areas have been directed by NEA to do residual spraying on all building surfaces.

Dormitory operators have also given mosquito netting and repellant to foreign workers.

The difference between malaria and chikungunya and dengue is that malaria is transmitted by the Anopheles mosquito while the other two infections are caused by the Aedes mosquito.

The Aedes mosquito tends to be active during the day and is found near human habitation generally, while the Anopheles mosquito is active at night and found in dense forestation or brackish water.