(VOVworld) - About 500 million people in the Americas are at risk of being infected with the Zika virus. Sylvain Aldighieri, an official of the Pan American Health Organization (PAHO), said on Tuesday that it's important to note that all countries which have reported or detected the Dengue and Chikungunya virus outbreaks during recent years, are considered at risk of outbreaks of Zika.

A nurse extracts blood from a pregnant woman as part of a general routine check, which includes examination for mosquito-borne viruses like Zika, at the maternity ward of the Hospital Escuela in Tegucigalpa, Honduras, April 15, 2016. [Photo/Agencies]

It means that Zika outbreaks are expected to spread from Middle America and Latin America to the north of Argentina and into the Caribbean. Aldighieri said so far 47 countries and territories have reported having Zika transmission, of which five countries, including Brazil, have reported microcephaly.

Anthony Fauci, Director of the US National Institute of Allergy and Infectious Diseases, said the Institute is working to begin a clinical test for a Zika vaccine in September. It would take from one to three years to prove whether the vaccine works or not, Fauci said.