It's a concern only in pregnant women or only in men who then have sex with someone or get someone pregnant. That's when it's a concern because, you're right; 80% majority don't know they're infected, and if they don't know, why would they think about it? Part of what we've had in terms of the testing is that if a pregnant woman has been travelling to the area and they come back, whether they've had symptoms or not, we advise them to talk to their doctor. If they want to be tested, we do the serology test and we're delighted to do that.
With men, we advise that they use a condom for at least two weeks following, and if they're having sex with a pregnant woman, to avoid it for at least the entire pregnancy. As well, if they're having sex with someone who could get pregnant, they should avoid it for a couple of months. Those are very conservative and they're being extra cautious, but it's for the very reason that they could transmit it and not know it.