Three cases of the deadly coronavirus have been confirmed in New South Wales, bringing the total nationwide to four.

NSW Health confirmed three men – aged 43, 45 and 53 – are being treated in Westmead Hospital in Sydney and are in isolation.

Victorian Health Minister Jenny Mikakos said that a case of the respiratory condition had been confirmed in a man who last week returned from China, where the city of Wuhan is considered the epicentre of the virus.

The man was in Australia for six days before being diagnosed.

The news comes as the death toll from the virus rises to 41 in China, where more than 1200 cases have been reported. Millions are in lockdown in China, with roads and schools closed and public transport cancelled. Many Chinese New Year celebrations have been called off.

One doctor is believed among the dead there.

In Australia, NSW Health Minister Brad Hazzard said 18 people across the state have now been assessed for the virus after samples were sent to a “world-leading” laboratory in Victoria, with 12 patients being “excluded” and three being confirmed on Saturday.

“I’d like to thank each of these three people because they have been exemplary in the way that they presented themselves (to health services),” Hazzard told reporters tonight.

All three men arrived on flights from China – one on January 6, one on January 19 and the other is being checked by authorities.

The Victorian case was the first confirmed case in Australia of “about a dozen” being investigated nationwide, an estimate put forward by Queensland’s Chief Health Officer Dr Jeannette Young on Saturday.

“It’s an evolving number,” she told reporters at a press conference on Saturday afternoon.

“We will be treating them as if they’re confirmed cases, as a precaution.

“We still don’t understand the transmissibility of this virus,” Ms Young explained, noting that treatment is symptomatic.

“If you develop fever, coughs or shortness of breath, you should ring ahead to your GP, discuss it and your GP will refer you to the emergency department.”

Queensland Health shared some good news in an update on Saturday night.

“Five people being assessed in Queensland for the Wuhan coronavirus have tested negative to the disease,” the department said.

Dr Young said one more person was being tested but their results will be available on Sunday.

She said they were taking “all precautions possible” and had stepped up their response with the State Health Emergency Coordination Centre. Public hospital emergency departments across Queensland will be instructed to waive testing fees for foreign nationals suspected of carrying coronavirus.