Officials sprayed insecticide and cleared drains of stagnant water in residential areas of Singapore at high risk of further Zika infections on Monday after 41 locally transmitted cases were confirmed in the city state.

Workers wearing fumigation masks traveled methodically through high-rise public housing estates in seven separate areas of the island, inspecting plant pots closely as they sprayed insecticide via thermal fogging machines.

The health ministry on Saturday confirmed Singapore's first locally-transmitted case of Zika, with the tally rising to 41 just a day later. All of the infected people were either residents of the Aljunied district or workers at a construction site owned by GuocoLand in the area.