Rise in Northern Ireland HIV cases
The number of people living with HIV in Northern Ireland has almost doubled over the past decade, health experts warned.
The country had the largest proportional increase in new diagnoses anywhere in the UK between 2000 and 2013, according to the Public Health Agency (PHA).
Dr Louise Herron, consultant in public health medicine at the agency, said: "By having unprotected sex you could effectively be sleeping with everyone your partner's ever slept with, putting yourself at risk of getting HIV or another sexually transmitted infection."
Northern Ireland had the largest proportional increase in new diagnoses anywhere in the UK between 2000-2013, and the overall number of people here living with the condition has almost doubled over the past decade, the PHA said.
It recorded 537 new episodes of uncomplicated gonorrhoea diagnosed in genito-urinary medicine clinics in 2013, compared with 451 in 2012 and 336 in 2011.
Dr Herron said the Health Survey Northern Ireland 2013/14 found that, in the 16 to 24 age group, around a quarter had three or more sexual partners in the last year.
Nearly a third agreed that drinking alcohol contributed to them having sex without using a condom.
She added: "People with STIs (sexually transmitted infections) don't always have symptoms, for example 24% of people with HIV don't know they have it, so anyone having unprotected sex could be putting their health at risk."
A special campaign will specifically target 16 to 34-year-olds as this age group has the highest rate of STIs, and encourage them to protect themselves.
Only one in nine people surveyed said they had attended a sexual health clinic.