The spread of Zika virus across the Americas is a public health emergency of international concern and deserves urgent attention, the World Health Organization said Monday.
"I am now declaring that a recent cluster of microcephaly and other neurological abnormalities reported in Latin America following a similar cluster in French Polynesia in 2014 constitute a public health emergency of international concern," WHO director-General Dr. Margaret Chan told a news conference.
WHO said last week that Zika was spreading "explosively" across the Americas and predicted 3-4 million people could be infected within a year.
It would not have been of concern -- Zika normally causes only mild symptoms at worst -- but Brazil noted a marked increase in cases of a severe and devastating birth defect called microcephaly that coincided with Zika's arrival. Some doctors also fear the virus may cause a paralyzing condition called Guillan Barre syndrome.
Some health experts accused WHO of acting too slowly and the organization's been under pressure to move more quickly against Zika.
Chan said travel restrictions are not called for at this time. The most important measures will be to protect people from the mosquitoes whose bites transmit the virus.
The spread of Zika alone would not be an emergency, said David Heymann, Chair of WHO's emergency committee. "Zika as we understand today is not a clinically significant infection," Heyward said. "It's only because of this association, if it is proven, that Zika could be considered as a public health emergency of international concern. That's why it was a very difficult deliberation."
"The evidence is growing and it is getting strong," Chan said.
There is not a whole lot WHO can do. The organization doesn't have a lot of cash to pour into research or immediate medical care. But the largely bureaucratic declaration can encourage countries to donate money, to coordinate efforts and, of course, it raises the profile of a disease outbreak.
The idea of a public health emergency of international concern has only existed since 2007. WHO has declared the emergencies for the H1N1 swine flu pandemic in 2009; for a resurgence in polio and for the Ebola epidemic in West Africa.
WHO has declined to call the spread of the Middle East Respiratory Syndrome (MERS) a public health emergency of international concern.
This article originally appeared on NBCNews.com.