The tally is up from only six confirmed cases in the first three months of 2024.
More than half of the 737 diagnoses throughout the year have been in NSW, while there have been another 254 cases in Victoria.
Mpox was first diagnosed in Australia in 2022 amid a global outbreak, such as in Congo in Africa. (AP PHOTO)
The vast majority of cases are among men, although two women have also been diagnosed.
Mpox is caused by the monkeypox virus, which is from the same family as the one responsible for smallpox.
Vaccinations against that disease have also been used to suppress mpox.
The virus is transmitted chiefly through prolonged physical or intimate contact with an infected person.
A painful rash, lesions or sores, fever, chills, muscle aches, swollen lymph nodes and sore throat are among the common symptoms.
Most patients fully recover, but some can become seriously ill.
Mpox was first diagnosed in Australia in 2022 amid a global outbreak, with 144 cases confirmed across the nation that year.
Cases were more suppressed in 2023, with 26 reported.
But researchers from UNSW's Kirby Institute warned of the disease's re-emergence in June after case numbers began rising in 2024, surpassing the previous year's total in the first six months of the year.
Some 275 cases had been recorded nationwide in September as of Friday, a new monthly peak.
Leaders of the Quad nations - Australia, United States, India and Japan - discussed combating the disease at a summit earlier in the month.
"We plan to coordinate our efforts to promote equitable access to safe, effective, quality-assured mpox vaccines, including where appropriate expanding vaccine manufacturing in low and middle-income countries," a joint statement said.
Vaccination is recommended for men who have sex with men, sex workers, healthcare and laboratory staff at risk of exposure.
Mpox was declared a global health emergency in August as a new strain began spreading from the Democratic Republic of Congo to neighbouring countries.
The strain is considered more deadly and more transmissible but is not believed to have hit Australia.
More than $800 million has been pledged to the Africa Centres for Disease Control and Prevention for its response to the virus.
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