Australia has seen a rapid rise in mpox cases in the past three months, with one health expert concerned that low vaccination rates could be driving a spike outside cities.

So far this year, 737 cases have been recorded, with the vast majority of cases occurring in the last few months.

In comparison, there were 26 cases last year and 144 cases in 2022. The majority of this year's new cases occurred in the southeastern states and only two cases were reported to be women.

A spokesperson for the Australian Department of Health and Aged Care told AFP that cases have been increasing since May this year.

Australia has responded by lifting restrictions on who can be vaccinated, allowing for "people of all ages who are at risk of exposure to mpox" to be eligible.

Matthew Shields, a Sydney sexual health physician and GP, told the national broadcaster ABC that the virus was being detected outside metro areas -- where vaccination rates are lower.

Mpox is caused by a virus transmitted to humans by infected animals that can also be passed from human to human through close physical contact.

Deadly in some cases, it causes fever, muscular aches and large boil-like lesions on the skin.

The virus gained international prominence in May 2022, when clade 2b spread around the world, mostly affecting gay and bisexual men.

In July 2022, the World Health Organization declared a Public Health Emergency of International Concern, its highest level of alarm.

Australia has yet to report a case of the new clade 1b variant of mpox that is believed to be more dangerous.