The Health Service Executive has said more cases of the Zika virus can be expected in Ireland, but most people will not know they have the disease.
Earlier, the organisation said the diagnosis of the first cases of the virus in Ireland is not unexpected, as many other European countries have reported infections.
The HSE says the two unrelated cases involved a man and a woman who had travelled to a Zika-affected country in the first four to five months. Both have recovered.
Speaking on RTÉ's Morning Ireland the Assistant National Director of Health Protection at the HSE said both adults returned to Ireland with a mild illness but there was no initial suspicion that it was Zika until people became more aware.
Dr Kevin Kelleher said 75-80% of people do not know they have it and that it is like a very mild cold or flu type illness.
Dr Kelleher, said the reason it has become a major potential problem is not the disease itself but the effect it appears to have on the unborn baby if the pregnant mother gets it.
He said they have become aware of this because it has moved from Africa and southeast Asia to the South Americas where a large number of people have never been exposed to it.
He said they would be recording more cases in Africa, but by the time, the vast majority of women get to their fertile age they have already been exposed to the disease and are immune.
Dr Kelleher said currently in South America all women between the age of 15-45 are becoming exposed to the virus for the first time and are unfortunately pregnant and that is why the effects are becoming obvious.
He said the likelihood is that no-one needs hospital treatment as a consequence of this disease.
He urged women who are pregnant or who want to get pregnant to decide if their need to travel to these areas is essential.
