Experts say almost every country in the developed world, including Australia, is experiencing significant and consistent rises in the rate of new HIV diagnoses among men who have sex with men (MSM).
While rates of HIV in New South Wales (NSW) have been stable, they have increased significantly in other Australian states. In NSW only an 8% increase in notifications among MSM has been seen, whereas Victoria has seen a 131% increase and Queensland has seen a 55% increase.
Australia has several nationally funded HIV centres but the response to the HIV epidemic is largely carried out by state and territory health departments and there are substantial differences around Australia.
The reason for this is unknown but it is suspected that it may be associated with differences in the management of sexually transmissible infections (STI) and HIV in different states in Australia.
Experts are now also concerned that 'complacency' is creating the risk of an HIV 'superinfection' as HIV-positive men who practise unsafe sex are becoming infected with additional strains of the virus.
In a study by scientists from the Melbourne Sexual Health Centre, research has revealed that that up to 4% of 145 HIV-positive Melbourne men could be "superinfected".
The study which is the first Australian research on HIV "superinfection", examined the viral load and the level of infection-fighting T-cells in the blood of the men.
The lead author and director of the Melbourne Sexual Health Centre, Professor Christopher Fairley says that while "superinfection" had been the subject of some research overseas, the paper was the first Australian research to implicate the phenomenon.
Professor Fairley says that if an HIV-positive person became superinfected, they could contract a drug-resistant or more virulent strain of the virus, which could be more difficult to treat and could progress more quickly to AIDS.
The study found that many gay men engaged in unsafe practices, despite being aware of the possibility of superinfection and concern about its damaging health effects, and Professor Fairle says the research provides infected people with a reason to continue to be safe, for their own individual protection.
Co-author Professor Sharon Lewin, the director of the infectious diseases unit at the Alfred hospital, says having HIV does not protect a person in any way from getting a second strain of HIV.
Professor Lewin says in gay men there are high rates of risky behaviour, even in people that are uninfected and the reasons are unclear.
The researchers suggest that as HIV no longer carries the stigma it did 20 years ago, and because treatments have improved, there is now a complacency about HIV.
The research is published in the CSIRO-published journal Sexual Health.