Those in close contact with a woman diagnosed with Covid-19 have been traced and notified, health authorities in the Republic have said.
She had flown from northern Italy to Dublin Airport before continuing her journey by land, reportedly using public transport.
It is understood she has been treated at home.
Dublin health chief Dr John Cuddihy said: "Each of the stages of this person's journey have been identified and all relevant contacts in all of those stages of transport have been contacted (and) traced."
A Coronavirus information stall has been set up at the arrivals gate in Dublin airport. If you have symptoms, phone your GP, and “stay away from other people”. pic.twitter.com/7A5wmedIcy— aoife-grace moore. (@aoifegracemoore) February 28, 2020
People who sat within two rows of the person on the plane from northern Italy to Dublin were contacted.
The woman followed advice in reporting concerns to a GP and "self-isolated" at home whilst awaiting the results of testing.
Dublin's Chief Medical Officer, Dr Tony Holohan, and the head of the Health Protection Surveillance Centre, Dr Cuddihy, held a news conference in Dublin to provide details of the Republic's preparedness.
Dr Holohan said they were depending on an individual with symptoms travelling back from an affected area identifying themselves, contacting the local health authorities, and that was what had happened in this particular case.
Public health protocols, similar to those used to respond to previous incidents of pandemic influenza, Sars and Mers, have been in place since January and are operating effectively, the officials added.
The positive result has been sent to Public Health England laboratories for verification.
A special unit has been established at the Royal Victoria Hospital in Belfast for isolating those suffering from the virus but the health authorities were unable to confirm where the individual is being treated.
Dublin's Health Minister, Simon Harris, said it was "not unexpected" and is to meet staff at Dublin Airport activating the public awareness campaign for Covid-19 this morning.
The Republic's National Public Health Emergency Team has been planning for this scenario since January.
The minister said the public should continue to adhere to public health protocols issued by the Department of Health.
er Lingus would not confirm whether the woman diagnosed with coronavirus travelled on the airline from Italy to Dublin.
Aer Lingus has confirmed that the person from Northern Ireland infected with Covid-19 travelled on the airline to Dublin airport.
In a statement the airline said: "Aer Lingus can confirm that the patient in Northern Ireland who has been diagnosed with the Covid-19 virus travelled with the airline from northern Italy to Dublin.
"Aer Lingus is co-operating fully with the HSE in relation to the Covid-19 developments and is liaising with the Department of Foreign Affairs, other government departments and the relevant authorities as required.
"Aer Lingus will continue to assess the situation based on the guidance received."