The World Health Organization is advising officials not to accept blood donations from people who recently returned from countries affected by the Zika virus.
The mosquito-borne virus is most prevalent in Latin America, particularly Brazil, and poses its greatest danger to pregnant women.
Doctors suspect the Zika virus is linked to a rare neurological condition called microcephaly, which causes babies to be born with abnormally small heads.
Brazil reports more than 4,000 microcephaly cases since October. But experts are puzzled why it is nearly non-existent in other Latin American countries where the Zika virus is present.
Spain confirmed the virus Thursday in a pregnant woman who recently traveled to Colombia. It is the first known pregnancy-related Zika case in Europe.
There is currently no treatment for Zika. But a number of global pharmaceutical houses are rapidly working on a vaccine.