Zika Virus Now a Global ‘Public Health Emergency,’ Says World Health Organization

February 1, 2016 Updated: February 2, 2016

With new Zika virus cases showing up in countries across the Americas, the World Health Organization (WHO) has officially declared a public health emergency over the spread of the disease on Monday.

The label “public health emergency” is used as a tool of last resort to encourage political action when the threat of an epidemic is dire. Last year, WHO was criticized for having declared such an emergency far too late into the Ebola crisis, when over 1,000 people had already died from the disease, AP reports.

The WHO estimates that the Zika virus could eventually reach over 4 million people, and last week the head of the WHO said that the disease was spreading “explosively.” The virus first reached the U.S. last week, and the number of patients is already up to 36.

The disease was first documented in Africa in 1947, but showed up in South America in 2014, when cases were detected on Easter Island, off the coast of Chile. The disease, spread by mosquitoes, is suspected of causing severe birth defects in babies of women who become infected while pregnant.

In Brazil, the number of infants born with microcephaly, a condition in which the infant is born with an abnormally small brain and is often mentally retarded, increased 20 times in 2015 after the spread of the Zika virus.

All known cases of the Zika virus in the United States are from travelers returning from Latin America, including Mexico.