Zika virus: Puerto Rico may see hundreds of birth defects, CDC says

A top U.S. health official is warning that dozens or hundreds of babies in Puerto Rico could develop severe birth defects because of Zika, based on how an outbreak is playing out there.

Screening of blood donations in the island territory has indicated a rapid increase in the spread of the virus. Officials expect infections will increase through the summer.

Consequently, Dr. Tom Frieden, director of the U.S. Centers for Disease Control and Prevention, said Friday that dozens or hundreds of births there could be affected.

The island has more than 1,700 Zika cases, including 191 in pregnant women.

• 'Not out of the woods if you don't have symptoms' in pregnancy, birth defect study finds

The Zika virus — spread mainly by mosquito bites — causes only a mild illness in most people. But infection during pregnancy can cause fetal deaths and potentially devastating birth defects.

Elsewhere on Friday, the World Health Organization said almost $122 million US is needed to prevent and manage the medical complications of the Zika virus.

A specific focus is needed on supporting women and girls of child-bearing age, the UN health agency said as it set out a revised joint strategy with the Pan American Health Organization (PAHO) for how to handle the mosquito-borne virus.

Zika has caused alarm throughout the Americas since cases of the birth defect microcephaly were reported in Brazil, the country hardest hit by the outbreak.

WHO director-general Margaret Chan said much had been learned about Zika, how it spreads, the consequences of infection and how to control it since global health authorities set out their initial response plans earlier this year. WHO declared Zika a global public health emergency in February.

"The response now requires a unique and integrated strategy that places support for women and girls of child-bearing age at its core," she said in a statement.