More than 10,000 cases of sexually transmitted infections were notified in the Republic last year, according to new figures published yesterday by the Health Protection Surveillance Centre.
They show reports of sexually transmitted infections are increasing year on year and last year they were up by 12 per cent.
Dr Mary Cronin, a public health specialist with the centre, said the main reason for the increase was people were putting themselves at risk by not practising safe sex.
"There are also other factors contributing to the increase," she said. "People are more aware of sexually transmitted infections now . . . people are more likely to present for testing."
There were now also more sensitive tests available for some types of infection, she added.
"The safe sex message has never been more important. One of the things we are very concerned about is that having a sexually transmitted infection can facilitate transmission or acquisition of HIV," Dr Cronin said.
Latest figures on HIV infections detected in the Republic in 2004 will be published separately in a few weeks.
The data published yesterday deals with instances of infections such as ano-genital warts, chlamydia, herpes, gonorrhoea, infectious hepatitis B and syphilis.
No data is provided on the country of origin of those who presented with infections but details are provided of their ages. Just over one in 10 of the cases notified last year - 1,174 cases - were in teenagers (those aged 19 or under). Some 55 per cent of cases - 5,983 - were in the 20 to 29 age group. A further 1,632 cases (15 per cent) were in the 30 to 39 age range.
The most commonly notified sexually transmitted infections (STIs) last year were ano-genital warts (4,174 cases), followed by chlamydia (2,803 cases) and non-specific urethritis (2,746 cases).
Health professionals are particularly worried about the increased incidence of chlamydia - notifications were up 24 per cent last year - as it can result in infertility. The report said notifications of this type of infection were likely to be an underestimate of "the true burden of disease" as this infection produced no symptoms in at least 70 per cent of women and in 50 per cent of men.
A separate report, entitled The Need for Chlamydia Screening in Ireland, was also published by the centre yesterday. It said screening programmes were in place in Sweden and the US and one was being rolled out in England.
It concluded that research was now needed on the incidence of chlamydia infection among different sub-populations in the Republic in order to inform policy on the need for screening here.
Meanwhile, the latest figures on sexually transmitted infections indicate there was a 38 per cent decrease in cases of syphilis notified last year. However, there was a 45 per cent increase in cases of gonorrhoea reported. Most of these cases were among men.
Most STIs were reported in the eastern region.