GENEVA: The World Health Organization will seek $25 million for a six-month program to fight the Zika virus linked to birth defects, including studies on whether it is spread by sex or by blood transfusion, a senior WHO official told Reuters on Friday.

Dr. Sylvie Briand, director of WHO's department of pandemic and epidemic diseases, said pregnant women in affected countries must have access to counseling and technology to make informed choices, including whether to abort fetuses with microcephaly.