Scientists worry that a little-known sexually transmitted infection is becoming resistant to treatment.
MG, or mycoplasma genitalium, is carried by up to 400,000 Australians, according to researchers' estimates cited by the Sydney Morning Herald.
The disease causes chlamydia-like symptoms, such as infection of the cervix or urethra.
And, like chlamydia, it can be spread through sexual intercourse, even if the carrier doesn't experience any symptoms, Daily Mail reports.
The infection is listed as "recently identified" on the Australian STI Management Guidelines webpage despite being discovered in the early 1980s.
One sexual health expert called MG "extraordinarily unrecognised."
"Many doctors don't really know about it, most doctors aren't testing for it," Catriona Bradshaw, sexual health researcher at Monash University and senior clinician at the Melbourne Sexual Health Centre, told the Sydney Morning Herald.
Dr Bradshaw said MG is becoming resistant to antibiotics, but that more wide-spread testing could counteract this trend.
"This resistance to frontline therapy has occurred over the last decade, has largely gone unnoticed because of the lack of availability of testing and the lack of surveillance," she said.
In January, the NSW-based company SpeeDx received approval from the Therapeutic Goods Administration to market the country's first commercial test for MG, the Sydney Morning Herald reported.
MG, or mycoplasma genitalium, is a sexually transmitted infection.
In men, MG causes urethritis (infection of the urethra, the urinary canal leading from the bladder to exit at the tip of the penis).
Symptoms may include watery discharge from the penis, and a burning sensation in the penis when urinating.
In women, MG causes infection of the cervix (opening of the uterus at the top of the vagina).
Symptoms are usually absent but may include: abnormal discharge from the vagina, discomfort on urination, and bleeding between periods, often after sex.
If untreated, MG can cause pelvic inflammatory disease in women.
Symptoms can appear up to 35 days after infection.
Source: SA Health