The World Health Organization declared a "public health emergency of international concern" Monday over the Zika virus and the health problems that doctors fear it is causing.
The agency said the emergency is warranted because of how fast the mosquito-borne virus is spreading and its suspected link to an alarming spike in babies born with abnormally small heads.
Reports of a serious neurological condition that can lead to paralysis have also risen in areas where the virus has been reported.
The conditions have not yet been conclusively linked to the virus.
But the large area potentially affected by the virus, the lack of vaccines and reliable diagnostic tests, and lack of population immunity in the affected countries contributed to the need for the declaration, according to the WHO.
Dr. Margaret Chan, the WHO director-general, described Zika as a major problem after the first meeting of the International Health Regulations Emergency Committee in Geneva, Switzerland.
"Members of the committee admit that the situation meets the conditions for a public health emergency of international concern," she said. "I have accepted this advice. I am now declaring that the recent cluster of microcephaly and other neurological abnormalities reported in Latin America following a similar cluster in French Polynesia in 2014 constitutes a public health emergency of international concern."
Last week, the agency said the virus was "spreading explosively" in the Americas, with as many as 3 million to 4 million infections possible over 12 months.