A sexual health specialist is warning the spread of syphilis will likely rise if workforce numbers are not boosted.
There are currently 15 specialists in New Zealand based in six cities and half of them are due to retire in the next five to 10 years.
Recent data tracking syphilis showed no detected cases in some of the regions which do not have specialists.
Experts say that is an example of the need to have specialists to lead each region. Undetected and untreated cases of syphilis can have severe impacts, particularly for babies born with congenital syphilis.
The bacterial disease is diagnosed with a blood test and can be treated with a shot of penicillin.
Dr Massimo Giola of the New Zealand Sexual Health Society said if it was not diagnosed and managed by sexual health physicians early, cases would rise and there could be major consequences.
"But it's not just babies, you know, we've had cases in New Zealand of people going deaf or going blind because the disease crossed the barrier between the blood and the brain, and they had what we call neurosyphilis."
Two years ago, New Zealand Sexual Health Society suggested a restructuring to Health New Zealand. It would have meant every region was overseen by a sexual health physician. But instead, a single national clinical advisor has been appointed.
Giola acknowledged it might have been a difficult time of change in the health system to be discussing this restructure.
While the news of clinical networks being established brought some hope, these would also require investment into the workforce, which was dwindling, he said.
If sexual health care did not improve, those most likely to suffer would be young people below the age of 25, men who have sex with men as well as other sexual orientation and gender diverse individuals, and Māori and Pacific people, he said.
"There are different reasons for each of these populations. But in a nutshell, it's [because of] difficulty to access care and that can be due to stigma, discrimination, or financial reasons, but essentially these three most affected populations really need an alternative point of access to sexual health care that, in our view, can only be provided by free public sexual health clinics across the motu."
The New Zealand Sexual Health Society said more than a third of women who were diagnosed with syphilis last year were pregnant.
Michael Meyer, a neonatologist and paediatrician at Middlemore Hospital, sees some of the most severe effects of rising syphilis cases. He cares for babies born with congenital syphilis - 40 percent of whom die.
Doctor on the devastating impacts of rising syphilis cases
Meyer told Nine to Noon there had been a dramatic increase in the number of full-blown or potential cases of congenital syphilis over the past eight to 10 years.
"It's one of those diseases that actually has a lot of different manifestations clinically, you can go from being pretty well, and not having any symptoms, to actually babies that are really, really sick.
"The organism has always been sensitive to penicillin, but in spite of the fact that we can recognise the disease and start treatment, some of the babies still don't make it, as you said, with quite a high mortality."
It was preventable though, especially if it was detected and treated early in pregnancy, he said.
"Oftentimes the mother doesn't have any symptoms at all, and this wouldn't have been an expected outcome, but it is one of the reasons that it's so important that the testing for syphilis is carried out on every pregnant woman and is indeed recommended.
"One of the issues is that there may not be engagement with the health system and some of the women book late in pregnancy and may not actually book at all, and those are the ones really where the risk is the highest and I think part of the issue also is having a higher awareness."
In a statement provided to Nine to Noon, Health New Zealand said the Sexually Transmitted and Blood Borne Infection (STBBI) strategy, published last year, aimed to improve collaboration and collective action.
It said it was delivering on its initial priorities, including implementation of the HIV Action Plan, National Hepatitis C Action Plan, and the priority actions in the National Syphilis Action Plan.
Health NZ also recently appointed a clinical advisor to provide specialised clinical advice and leadership, including strengthening connections with regional sexual health services.