New Zealanders are being warned against complacency after a jump in the number of men infected with the Aids virus.
The Aids Foundation says the number of HIV cases among men who have sex with men was the highest last year since 1996.
Kevin Hague, the foundation's executive director,said 50 men were found to be infected with HIV through antibody testing, a rise from a stable number of about 35 over each of the previous four years.
Mr Hague said it was cause for concern, although the numbers were still small and a few more cases could mean a big percentage change.
"Fifty diagnoses over one year amounts to almost one diagnosis a week. Although it's possible that some of these infections may have been acquired some time ago or that last year's high number of diagnoses is an aberration, it means that gay men are still becoming infected with HIV in New Zealand."
Mr Hague said new HIV treatments (called Highly Active Anti-Retroviral Therapies - or HAART) in the mid-1990s improved the health of many people with HIV, particularly by limiting the progression of HIV to an Aids-defining illness.
"However, health promoters have feared for some time that the decreasing public visibility of Aids might lead to heightened complacency about HIV."
He said that could lead many uninfected gay men into believing that HIV was no longer a significant personal threat.
"As much as some people might like to pretend HIV has gone away, it hasn't."
Mr Hague said that as the third decade of the Aids epidemic approached, the risks associated with any one occasion of unprotected intercourse had increased.
"This is because there are more HIV positive individuals in New Zealand than ever before. Many are aware of their infection because they have tested positive, but some are not."
In Western countries about a third of people infected with HIV were not aware of it. "It's therefore important for people not to assume that their sexual partner is HIV negative."
