A NSW man in his 50s is the third person to contract monkeypox in the state after recently returning from Europe.
The man developed a mild illness several days after arriving back in Sydney, NSW Health said on Friday.
He is isolating at home and his case is not connected to two previous cases detected in NSW.
The viral disease can be transmitted from person to person through air droplets, close bodily contact or sharing contaminated linens or objects.
Symptoms include having a fever, headache, muscle aches and exhaustion.
NSW chief health officer Kerry Chant tempered worries about the spread of the disease.
"Monkeypox does not present a transmission risk to the general community, and has until recently not been an infection most clinicians in NSW would have been looking for or concerned about in their patients," she said.
The World Health Organisation said 23 countries that are not endemic for monkeypox virus have reported cases since mid-May.
Community health charity ACON has advised men who have sex with men to be vigilant for symptoms.
