The tourism industry may not fully recover from the foot-and-mouth crisis for some years, Bord Failte has said.
Mr John Brown, press officer for the State tourism board, said an aggressive marketing campaign would be essential to get the US market in particular "back to normal".
"I was speaking to an American tour operator in early May and he was saying the view there was that it may take a couple of years for the market here to get back to full swing.
"This [industry] is not something that can be turned off and on just because the [foot-and-mouth] restrictions have been lifted."
While there were six million overseas visitors to the State last year, that figure is expected to be down by one million this year. "The knock-on effect of the restrictions this year may well last into the next year and possibly even longer," said Mr Brown.
"If a market has a bad feeling about a country, that feeling lingers a little longer than we might like. People turn somewhere else and it will take an aggressive effort to win them back."
The losses in the domestic market simply could not be won back.
"The losses I'm talking about are the meetings and conferences which were cancelled. Tourism can be a very perishable thing. Once people decide not to have a conference in April, it isn't a question of having one later. What is lost is lost and can't be won back." The comments come as the Government and a number of regions embark on all-out efforts to win back tourists.
While projected losses have been estimated at anything between £500 million and £700 million by the end of the year, the Minister for Tourism and Sport, Dr McDaid, has said even these may prove to be conservative.
Bord Failte's chief executive, Mr John Dully, has said job losses in the industry could run to 20,000.
The worst affected area has been Co Louth, following the outbreak of foot-and-mouth in the Cooley peninsula. It had been particularly badly hit by the restrictions on cross-Border travel, said Mr Brown, with retailers in Dundalk reporting business down by up to 40 per cent.
The mid-west and Shannon regions have seen spending on tourism drop by more than £60 million on the £300 million normally spent there each year.
Killarney, Co Kerry, is expecting to see minimum losses of £5 million this year.
Since March, Irish Hotels Federation members have reported losses of up to £35 million, while restaurant revenues are down by an estimated 30 per cent, according to the Restaurant Association of Ireland.
The downturn this year will be the first in 13 years, said Mr Brown. "Getting visitor numbers back to normal is going to take a lot of hard work."
