David Heymann, who chairs the WHO's Emergency Committee on the epidemic, said on Friday that the Zika pandemic remains to be in emergency level and warned that the virus is spreading out to new countries throughout the world.
Heymann, who is an epidemiologist, further warned that knowledge about the Zika disease was limited and there were considerable gaps between an understanding of the disease and the complications caused by the infection, including a kind of brain damage called microcephaly found in babies infected with the virus.
The organization said that to date, Zika had reached 72 countries and territories.
Meanwhile, health researchers say threat from the Zika virus is at its highest point in places where the environment is suitable for mosquitoes, especially during the warm summer months when mosquitoes can live longer.
Researchers, however, are still unsure which species of mosquitoes spread the virus, and how the virus acts on its victims after being infected.
The Zika virus, which was first identified in the Zika Forest of Uganda in 1947, has since been known to occur in equatorial regions in Africa and Asia.
However, since 2007, the virus has moved eastward, across the Pacific Ocean, into the Americas, hitting Brazil, Colombia, the Dominican Republic, Ecuador, El Salvador, Honduras, Mexico, Panama, Paraguay, Venezuela and the United States.
It is estimated that in Brazil alone, 1.5 million people have been infected by Zika with over 3,500 cases of microcephaly reported between October 2015 and January 2016, according to media reports.
Infection caused by the Zika virus results in mild or no symptoms in patients in many cases. However, in severe cases it can cause fever, red eyes, joint pain, headache, and a maculopapular rash, usually lasting several days.
Infection during pregnancy could result in microcephaly and other brain malformations in babies.
There is no known vaccine for Zika and there have been no confirmed deaths associated with the virus so far.
Efforts to eliminate the virus by killing carrier mosquitoes has resulted in the death of multitudes of honey producing bees sprayed with insecticide.