MANILA • The Philippines yesterday reported its first known case of a pregnant woman infected with the Zika virus that threatens unborn babies, as the authorities warned people to avoid mosquitoes.

The pregnant woman was one of three new cases of Zika infection reported by the health department.

Health Secretary Paulyn Ubial said 12 cases of Zika had been detected across the Philippines this month, including the 22-year-old woman from the central island of Cebu who is 19 weeks pregnant with her first child.

"Initial ultrasound did not detect any foetal abnormalities. She will be monitored regularly during the entire period of the pregnancy," the health department said.

Zika-infected pregnant women can give birth to babies with microcephaly, a deformation marked by abnormally small heads. Of the country's 12 Zika cases, eight were female and ranged in age from nine to 55, the department said.

"These cases did not have history of travel to an affected country a month prior to the onset of their illness," it added, indicating that the virus was locally transmitted.

Ms Ubial has ordered all health workers, especially in regions where there are Zika cases, to be more vigilant and to wage a more intensive mosquito-control campaign to eradicate mosquitoes.

AGENCE FRANCE-PRESSE, XINHUA