UPDATED 7.58pm: Canterbury Police are speaking to the sexual partners of a man who allegedly admitted to a doctor he didn't tell lovers he's HIV-positive.

Police have received a complaint that 26-year-old Johnny Lumsden had unprotected sex with several men, without telling them his HIV-status.

Two men have been cleared of having the condition and one is awaiting test results.

If the third is infected, it's possible that Lumsden could be charged with wounding with intent to cause grievous bodily harm.

Detective Senior Sergeant Scott Anderson said they're interested in speaking to anyone else who may have had unprotected sex with Lumsden.

"In the first instance they should be having a sexual health check and then coming to see us if they'd like to pursue it any further."

Some former partners have already been spoken to, Anderson said.

"Some didn't fall into the category of unprotected sex, some already had the HIV virus, and a number of others didn't want to engage with the police," he said.

Although police are focusing on encounters in Canterbury, there could be more partners to come forward, with Lumsden having lived in Australia. He is originally from Northland, Anderson said.

An HIV expert says although condom use may fall to the way side methods used overseas to combat the spread of HIV infections have proven success signs.

Auckland University academic and HIV expert Dr Rick Franklin said condom use recommendations should be increased in combination with taking prophylactics.

He said in reality HIV infection rates go down which is a public health bonus.

National Co-ordinator for Positive Women Jane Bruning said the stigmatisation can cause some people to behave in certain ways.

"If we can get the community to be a bit more open around what HIV is and how to reduce that stigma then people are not going to be so afraid and they will be okay to disclose and go forward."

She said she doesn't condone the young mans actions but says many HIV positive people live in fear of speaking out.

"That stigmatisation absolutely paralyses some people into behaving in a way that doesn't make them deviant or horrible people. They are just absolutely paralysed."