A syphilis outbreak has been declared in Adelaide, as health authorities warn unborn babies could die if the infectious disease transmits through the womb.

Key points: A syphilis outbreak has spread to Adelaide

A syphilis outbreak has spread to Adelaide There have been 64 cases reported in SA, including an infant, since 2016

There have been 64 cases reported in SA, including an infant, since 2016 An outbreak of the disease started in Queensland in early 2011

SA Health issued an alert to medical practitioners, advising the syphilis outbreak had formally been extended to Adelaide after previously being in place in the state's Far North, Eyre Peninsula and western regions.

The outbreak began in regional Queensland in 2011, and since then thousands of people across four states have been infected.

The Federal Government's response to the outbreak — which includes rapid response tests — is yet to reach South Australia.

It has been rolled out in regional centres in Queensland, the Northern Territory and Western Australia.

SA Health communicable disease control director Louise Flood said there had been a "small but sustained increase in syphilis cases in metropolitan Adelaide over the past six months".

The new 'rapid' test kits will immediately identify if someone has syphilis ( ABC News: Allyson Horn )

"All doctors are advised to offer syphilis testing to Aboriginal and Torres Strait Islander people to assist in controlling the outbreak," Dr Flood said.

"Locating, testing and treating the partners of infectious people is also important in controlling syphilis.

"We are working with the Commonwealth as part of the Multijurisdictional Syphilis Outbreak Working Group to monitor the outbreak and coordinate the public health response."

Increase in infections in South Australia

SA Health figures showed 49 people had been diagnosed with syphilis linked to the outbreak in the Far North, Eyre Peninsula and western regions since the outbreak was declared in those areas in November 2016.

A further 15 cases have been diagnosed in metropolitan Adelaide, with an increase in carriers in the past six months.

Among the cases diagnosed in regional South Australia last year was an infant born with congenital syphilis — the first baby to be born in the state with the potentially fatal disease in 18 years.

A poster for a Young, Deadly, Syphilis Free campaign. ( South Australian Health and Medical Research Institute )

In October, health professionals told the ABC it would take years to bring the infection rate down nationally, and called for the Government to fund a sustained and long-term prevention program combining sexual health education with training.

According to Federal Health Department data, there have been more than 2,300 syphilis cases notified across the four jurisdictions. Up to seven babies have died.

SA Greens MLC Tammy Franks said urgent action was needed from both levels of government to get the outbreak under control.

"We have a plan to tackle this, but that plan is lacking in both resources and rollout," she said.

"We know what to do, but we're not doing it.

"The national strategy should be bringing this under control and clearly the Government needs to give more resources as a priority to this.

"It's just unbelievable that in 2018 we're seeing syphilis diagnosed in a capital city."

SA Health Minister Stephen Wade said the State Government would "continue to do what we can try to deal with this outbreak".

"One of the things we've done is to establish a South Australian syphilis register to strengthen our capacity to treat and follow up confirmed and probable cases of infectious syphilis," Mr Wade said.

"We'll continue to work with Aboriginal and Torres Strait Islander organisations and with other health professionals and organisations to make sure our resources are targeted for the maximum impact on this outbreak."

A federal Health Department spokeswoman said it was engaged in discussions with SA Health, the Aboriginal Health Council of SA and Aboriginal Community Controlled Health Services about the outbreak, as well as "potential sites and approaches to rollout of the syphilis-enhanced response in the state".

"It is important to note that outbreak response is primarily a state responsibility," she said.

Disease a risk to mothers and unborn babies

The alert sent out by SA Health warned that the highly-infectious disease could be transmitted from pregnant mothers to their unborn babies, which could result in perinatal death, premature delivery and congenital abnormalities.

In South Australia, there have been five cases of infectious syphilis diagnosed in pregnant women.

Syphilis also increases the risk of HIV infection, and if left untreated can cause long-term damage to internal organs.

It can usually be treated with antibiotics including penicillin.