The World Health Organization has declared the spread of Zika virus an international public health emergency

The World Health Organization has declared the spread of Zika virus an international public health emergency and has freed funds to combat the disease.

“This is an extraordinary event,” said WHO Director General Margaret Chan at a press conference on  Monday. “It poses a public health threat to other parts of the world and a coordinated international response is needed.”

Margaret Chan cited the pattern of the disease’s spread, the lack of a vaccine, and the large global population of mosquitoes that can carry the virus as factors that contributed to the declaration.

The declaration, only the fourth in WHO’s history, comes just days after the organization said the number of cases could hit 4 million by the end of the year. The virus has spread rapidly throughout the Americas infecting people in more than 20 countries. 

Officials in Brazil, the hardest hit country, have estimated 1.5 million infections. 

The Zika virus is spread to people through mosquito bites and causes genetic mutation in babies. The most common symptoms of Zika virus disease are fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild with symptoms lasting from several days to a week.