NSW Health has warned the state may have seen the first cases of monkeypox being caught through local transmission.
Eleven cases of monkeypox have now been identified in the state.
While nine cases are likely to have been acquired overseas, two may have been acquired in Australia.
NSW Health's Jeremy McAnulty said people needed to be on alert for monkeypox symptoms now local transmission may be occurring, especially among men who have sex with men.
"People need to be aware of the symptoms of monkeypox, which can include fever, headache, body aches and a rash or lesions on the genital area," Dr McAnulty said.
'So far, in the cases we have seen in NSW, monkeypox is not presenting the way some people expect, such as an extensive rash or lesions all over the body.
"It could just be a couple of what seem to be pimples in the genital area or buttocks, so people need to pay careful attention to any potential symptoms. Most of our cases to date have presented to sexual health clinics, rather than GPs."
Dr McAnulty said people who have any of these symptoms should immediately call ahead to their GP or sexual health service for an appointment, tell them of their symptoms and make sure they wear a mask as a precaution.
"The virus is mainly spread through skin to skin contact with the lesions or rarely through close contact with large respiratory droplets from a person early on in their infection," Dr McAnulty said.
"It is important that people with symptoms avoid close contact with others, including sexual activity, as condoms are not effective at preventing the transmission of monkeypox."
Monkeypox is a rare viral infection previously associated with travel to Central and West Africa.
However, thousands of cases of monkeypox have been reported from several countries that are not endemic for the virus this year, including several European countries and the United States.
Many of the cases are men who have sex with men.
Infection needs to be confirmed by testing the blister fluid or scabs from the skin rash.
These symptoms usually begin seven to 14 days after exposure and most people recover within a few weeks.
