Africa, Asia and southern Europe all at risk, says leading WHO specialist, and the virus could devastate poorer nations, with a vaccine still potentially years away

The Zika virus, linked to thousands of birth abnormalities in Latin America, could spread rapidly across the globe to parts of Asia, sub-Saharan Africa and potentially southern Europe, a senior World Health Organisation expert has warned.

Dr Anthony Costello, a British paediatrician who is the WHO’s head of child health, said scientists were racing to plug gaps in their knowledge about the impact of the illness, which causes only mild symptoms in adults but appears to have devastating effects on unborn children by causing microcephaly, abnormally small heads.

Brazil, one of the worst-hit countries, has announced a nationwide assault on the mosquito responsible for transmitting the virus and President Dilma Rousseff vowed to “win this war” against the insect.

In a sign of the growing concern at Zika’s global spread, Public Health England last night advised men to use condoms for at least a month if they had returned from one of the 23 countries in the Americas where the virus is now present if their partner was pregnant, or at risk of becoming so. PHE said the risk of sexual transmission was very low but condoms should be used as a precaution.

As the WHO prepares to decide on Monday whether to declare an international health emergency, experts warned the “explosive” movement of the virus across the Americas meant it has the potential to spread further.

Dr Costello told The Independent: “We are seeing a very rapid spread of the Zika virus across Latin America. One very significant concern is that it seems possible it could move into other parts of the world with vulnerable populations. “These are places within the tropical belt and beyond – sub-Saharan Africa, Southeast Asia, southern parts of the United States and southern Europe.”

He warned that a vaccine may take years to develop, and added that experts dealing with the dramatic rise in Zika cases in Latin America were being hampered by the lack of a commercially available diagnostic test as they try to track and investigate the virus.

Dr Costello echoed the concerns of WHO’s director general, Dr Margaret Chan, who warned this week that Zika is spreading “explosively” across the Americas. Since the first cases in Brazil early last year, the virus has spread to 23 countries and territories, prompting epidemiologists to warn of up to four million cases a year across the continent.

Dr Costello, renowned for his work on improving survival rates among newborns in developing countries, told The Independent that medics were concerned that the speed of Zika’s spread since its last outbreak on a group of Pacific islands in 2007 means it will jump to other continents.

Speaking from WHO’s headquarters in Geneva, he said: “It seems possible that the virus could move back into other parts of the world with vulnerable populations, places within the tropical belt and beyond – sub-Saharan Africa, South-East Asia, southern parts of the United States and southern Europe. Some of these places will be better able to deal with that threat than others.”