Australia has solidified its reputation as a world leader in HIV prevention, recording its lowest number of new HIV cases in almost two decades.

However, challenges remain in reducing transmission among heterosexuals and the Indigenous population.

Key points: 835 HIV diagnoses in 2018, compared to 2,412 at peak of epidemic in 1987

835 HIV diagnoses in 2018, compared to 2,412 at peak of epidemic in 1987 23 per cent decline in HIV rates in Australia over past 5 years

23 per cent decline in HIV rates in Australia over past 5 years No declines among heterosexuals or Aboriginal and Torres Strait Islander populations

New figures released today by the Kirby Institute at the University of New South Wales reveal 835 HIV diagnoses were made in 2018, the lowest number on record since 2001.

The figure represents a 23 per cent decline in cases nationally in the past five years, to a rate that is nearing a third of what it was at the peak of the AIDS epidemic in 1987.

"This reduction is very encouraging," said Professor Rebecca Guy, head of the Kirby Institute's Surveillance, Evaluation and Research Program.

"Although we've seen reductions in recent years in some Australian states, in 2018 we saw significant reductions at a national level."

She said widespread HIV testing and treatment, alongside the introduction of HIV preventative medicine Pre-Exposure Prophylaxis, or PrEP, was behind the public health success.

"More people are being tested for HIV than ever, people living with HIV are starting treatment earlier, and we're seeing a very promising uptake of PrEP among gay and bisexual men."

Over the past five years, HIV diagnoses among gay and bisexual men have reduced by 30 per cent.

However, the number of new cases among heterosexual Australians, Aboriginal and Torres Strait Islander people, and gay and bisexual men born overseas has remained largely unchanged.

"This really indicates to us there's a lot more work to be done, and we need further enhanced and targeted initiatives," Professor Guy said.

"We have to remember that HIV is still associated with significant stigma and causes considerable morbidity in people who don't receive treatment."

Increased uptake of PrEP

Andrew Grulich, head of the HIV epidemiology and prevention program at the Kirby Institute, said the introduction of PrEP in Australia had "turned the HIV epidemic in gay and bisexual men around".

PrEP, a pill taken daily to prevent the transmission of HIV between men during sex, was added to the Pharmaceutical Benefits Scheme in April 2018. Since then, data shows an additional 18,530 individuals have begun taking the preventative treatment.

"We're really quite pleased with how many gay and bisexual men have embraced PrEP as a way to protect themselves from HIV," Professor Grulich said.

"However, for declines to continue at this impressive rate, PrEP coverage needs to be significantly higher."

In Australia, approximately 41 per cent of gay men at high risk of HIV were taking PrEP in 2017.

Modelling suggests at least 75 per cent would need to take PrEP in order to achieve the elimination of HIV transmission in this high-risk group.

Professor Grulich said gay and bisexual men from culturally and linguistically diverse backgrounds should be the target of future PrEP rollouts, as well as gay men living in outer suburban, regional and rural parts of Australia.

"But it isn't just PrEP," he said, "it requires continued focus on testing, treatment, and condom promotion, which will help us continue the decline of HIV."

Targeting Indigenous populations

In addition to the expansion of PrEP, culturally-appropriate, community-focused campaigns were required to increase HIV testing and treatment in Indigenous populations, said James Ward, an Indigenous health expert from the South Australian Institute for Health and Medical Research (SAHMR).

"There has been no significant change, and certainly not a corresponding decrease [in the Aboriginal population] as has occurred in the non-Aboriginal population," Dr Ward said.

"That's despite Aboriginal and Torres Strait Islander people being noted as a priority population in policy and clinical guidelines."

In contrast to the non-Aboriginal population, a higher percentage of HIV cases among Indigenous Australians occur in women (almost one fifth), and as a result of injecting drug use.

Dr Ward said health promotion messages targeting women, people who inject drugs, and gay and bisexual men in regional and remote areas were needed "to ensure Aboriginal and Torres Strait Islander people are not left behind".

"I find it surprising that there are Aboriginal people still being diagnosed with AIDS in Australia, and being hospitalised," he said.

"Clearly, people are not benefiting from treatment, whether they're not engaged with health services by choice, or health services are not following up."

Earlier this year, the Federal Government announced $20 million in funding to address the disproportionate rates of blood borne viruses (BBV) and sexually transmitted infections (STI) in Aboriginal and Torres Strait Islander communities, including rates of HIV.

"This funding recognises the additional barriers and challenges which contribute to the impact of BBV and STIs on First Australians, and will be used to support a revitalised approach to prevention and treatment," a Health Department spokesperson said.

Australia leads world in prevention

While there is more work to do to make sure prevention measures and treatments reach everyone, Professor Grulich said the nationwide decline in HIV diagnoses was being seen in "very few other places in the world".

"I think one of the reasons why we, as a nation, have seen declines … is because of our universal health care system," he said.

Australian Federation of AIDS Organisations CEO, Darryl O'Donnell, said Australia had a role to play in demonstrating to the rest of the world how "powerfully effective" prevention, testing and treatment can be.

"At this point in the epidemic, to see these kinds of numbers is really quite profound, quite exciting. And we should celebrate that," Mr O'Donnell said.

"Because what underlies these numbers is incredible efforts both at the community level by gay men who have born that burden of HIV, but also by governments and researchers and clinicians."

Almost 37 million people worldwide are living with HIV, with an estimated 1.8 million new cases every year.

The Joint United Nations Program on HIV and AIDS has set global targets.

By 2020 it would like to see 90 per cent of people living with HIV diagnosed and treated, and for 90 per cent of people receiving antiretroviral therapy to have viral suppression.

The Kirby Institute's full 2019 Annual Surveillance Report on HIV, viral hepatitis and sexually transmissible infections will be available in November.