A new virus invading parts of Central and South America and now the Caribbean is causing concern among people living in and travelling to infected countries.

Transmitted by the aggressive Aedes mosquito, the Zika virus has spread to at least 23 countries and will likely infect tens of millions of people in a few short years.

Most won’t even know they’re infected, and the virus may lead to birth defects.

“In about 20-25 per cent of people, they know they have it, and it feels like a viral syndrome, like a flu,” said Dr. Brian Ward, a specialist on tropical diseases at the Montreal General Hospital.

There may be a connection between the Zika virus and pregnant women.

“There seems to be an increase in the number of congenital malformations, loss of babies and particularly microcephaly where a child is born with a very small head and a severely damaged brain,” said Ward.

The World Health Organization said it can't say conclusively there is a connection, but some evidence does point to that.

”The big task is to try to establish the link, what is the link, is it Zika alone is it Zika with something else together?” said Christian Lindmeier of the World Health Organization.

The Zika virus is causing so much concern a number of Latin American and Caribbean countries are warning women not to get pregnant until there is more evidence of a link.

The virus is also causing concern among pregnant women booked to travel to infected areas.

Travel agent Katia Pisanu of Over Travel said Quebecers love to go south during our cold winters, but is advising her pregnant clients against it for now.

Health Canada is also advising against it, though there is no official ban.

There hasn't been any stop in any country per se,” said Pisanu. “It's very difficult to do that because mosquitos are mosquitos and they travel and it's something that you really can't control.”

There is no concern in Canada, because the mosquito carrying Zika does not travel north.

Dr. Ward agreed it's best for pregnant women to stay home for now, because the dangers are very real.

“In an area where Zika is just invading, which is what is happening now in many countries in the Caribbean and Latin America, a fairly frightening portion of the mosquitos can be positive, so if you're a traveller going into one of those infected areas, you are at a reasonably high risk of acquiring Zika,” he said.