Singapore urged all pregnant women showing symptoms of fever or rashes to have themselves tested for the Zika virus on Wednesday after the number of cases in the city-state soared to 82.

The United States and Britain joined Australia and Taiwan in advising pregnant women to avoid nonessential travel to the city-state.

Environment agency workers stepped up efforts to eradicate mosquitoes that spread the disease, expanding a fumigation campaign centered on the "ground zero" of the outbreak, the eastern suburb of Aljunied.