"A person with undiagnosed HIV cannot tell someone they're infected and might not initiate safe sex. The practical reality of this is that everyone, especially gay men, needs to become better educated, supported and proficient at safe sex to control HIV and other sexually transmitted infections,"
The study, carried out in February last year, recruited 1049 gay and bisexual men from community settings.
Participants completed an anonymous questionnaire and provided an anonymous saliva specimen, which could be linked together by a unique code.
The researchers compared respondents' self-reported HIV test history with their saliva result to find 1.3 per cent of HIV positive men did not know they were infected.
Most believed they did not have HIV, and many had previously tested for HIV.
The overall HIV infection rate was the same for European and Maori participants, but non-European respondents were less likely to be aware they had HIV.
Younger infected gay men also appeared to be less likely to be aware of their infection.
Dr Saxton said while testing was a cornerstone of control and needed to be made more accessible, testing alone was not the answer.
"There will always be a lag between infection and diagnosis, and a person is particularly infectious early in the course of HIV infection when partners can be exposed unwittingly. This is why condom use remains key to control of your own and your partner's risk," he said.
HIV positive people who remained undiagnosed delayed treatments that could improve their quality of life and life expectancy.
"While treatments don't eliminate the HIV virus, they keep it at low levels and also reduce a person's infectiousness to others."
The research, carried out by Otago University's AIDS Epidemiology Group, was a collaboration with the New Zealand AIDS Foundation.
The findings were published in the journal BMC Public Health.
