Data has revealed gonorrhoea cases have increased by 63 per cent in the past five years, particularly among young city-dwelling heterosexual men and women.
Between 2012-2016, rates among men rose by 72 per cent and 43 per cent in women.
Infectious disease physicians were left dumfounded when increased testing, antibiotic resistance and a lack of condom wearing were all largely ruled out as the cause for the concerning spike.
Associate Professor of Medicine at ANU, Dr Sanjaya Senanayake says it is a real mystery.
Dr Senanayake also says some experts are now investigating whether gonnorrheoa can be transmitted through kissing.
'Through oral sex it can end up in the throat and it could potentially be transmitted that way,' he said.
Some small studies have supported the theory, but it is yet to be proven, Dr Senanayake said.
Professor of Sexual Health at the Kirby Institute, Basil Donovan, says there is a 'very real' chance that kissing has become an issue for the spread of the STI.
'There's some evidence coming out of Melbourne that's certainly pointing that way, I'd like to see it replicated but I wouldn't call it undeniable,' Professor Donovan said.
However, the increasing number is likely due to the increasing number of young Australians having oral sex, Prof Donovan says.
'We've had two rounds of the national sexual behaviour survey, one in 2002 and one in 2012, and what was clear, was that amongst heterosexuals ... the proportion reporting oral sex was going up quite substantially.'
The sexual behaviour expert says new strategies are needed to combat the public health issue.