NSW Health has identified a probable case of monkeypox in a recently returned traveller to Europe.

A man in his 40s developed a mild illness several days after arriving back in Sydney. He subsequently presented to his GP with symptoms clinically compatible with monkeypox. Urgent testing was carried out which has today identified a probable case of monkeypox, with confirmatory testing underway.

The man and a household contact are isolating at home, with care and support being provided by their GP and NSW Health.

Cases of monkeypox have been identified in several non-endemic countries in recent weeks, including several European countries and the United States.

NSW Chief Health Officer Dr Kerry Chant said NSW Health has taken steps to ensure it identifies and appropriately managed any potential monkeypox cases.

"NSW Health has issued a clinician alert to GPs and hospitals across the state and has also been in contact with sexual health services to increase awareness of the cases identified overseas and to provide advice on diagnosis and referral. We will be speaking with GPs about this issue again today," Dr Chant said.

Dr Chant said monkeypox is a rare viral infection that does not spread easily between people and is usually associated with travel to Central or West Africa, where it is endemic.

"Cases are occasionally reported in non endemic countries in returning travellers or their close contacts, or in owners of imported pets. People can contract monkeypox through very close contact with people who are infected with the virus," Dr Chant said.

"The infection is usually a mild illness and most people recover within a few weeks."

NSW Health will continue to work closely with its colleagues throughout Australia to monitor for cases and ensure the best clinical response if any are identified.

Further information on monkeypox is available from the World Health Organization