The infection, which causes symptoms including mild fever, conjunctivitis and headache, has already been found in 21 countries in the Caribbean, North and South America.

It has been linked to thousands of babies being born with underdeveloped brains and some countries have advised women not to get pregnant.

No treatment or vaccine is available.

The virus was first detected in 1947 in monkeys in Africa. There have since been small, short-lived outbreaks in people on the continent, parts of Asia and in the Pacific Islands.

The Pan American Health Organization (PAHO) warned pregnant women to be "especially careful" and to see their doctor before and after visiting areas affected by the virus.

Colombia, Ecuador, El Salvador and Jamaica last week recommended women delay pregnancies until more was known about the virus.

Prof Laura Rodrigues, a fellow of the Brazilian Academy of Sciences and from the London School of Hygiene and Tropical Medicine, said some data suggested that up to one-in-fifty babies had birth defects in one of the worst hit areas - Pernambuco state in Brazil.

She said: "Until November we knew nothing, this has caught us by surprise and we're trying to learn as fast as we can.

"Wherever there is dengue, there is mosquito, then it will spread and not just in Americas I think there is a very real chance it will spread in Asia."

PAHO advice is to ensure all containers that can hold even small amounts of water should be emptied and cleaned to prevent mosquitoes breeding.

And that people should protect themselves by using insect repellent, covering up and keeping windows and doors closed.

The director general of the WHO, Margaret Chan, said the outbreak was "extremely worrisome".

(BBC News)

Related Articles

More babies affected with Zika virus