With three new cases in the last seven days, Australia now has 44 confirmed cases of monkeypox, including 24 in New South Wales and 16 in Victoria.

Globally, cases have begun to escalate rapidly, particularly in the US where the number has soared 33 per cent in the past three days, totalling 2881.

European nations dominate a list of the 10 worst-affected countries.

Spain sits above the US, with 3596 cases, while Germany, the United Kingdom and France round out the top five.

Australia is ranked 24th, and New Zealand has just two cases.

Outside of NSW and Victoria, officials have reported two cases in the Australian Capital Territory, and one each in Queensland and South Australia.

This week NSW Health declared the monkeypox situation was "changing rapidly".

Local transmission had probably occurred in a small number of cases, health officials said, a notable difference to people catching the virus abroad and then returning home.

"Many of the cases are in men who have sex with men and have been acquired overseas," the department said in a statement.

Mater Hospital's Dr Paul Griffin told 9news.com.au he was "definitely surprised" by the surge in cases around the world over the past fortnight.

"We're going to see a lot more cases (globally) before we get this under control," he said.

When asked if he was concerned about the situation in Australia, Griffin said it should be "relatively easy" to control with the most basic infection control precautions.

He also doubted there were unreported cases of the virus circulating in the country.

"I think the chance of us having missed cases is actually pretty low," he said.

"Forty-four cases is significant and it does highlight the fact we need awareness around the country to make sure we don't miss any cases and we can contain this fairly quickly."

Australia has only approved one of two smallpox vaccines that work for monkeypox.

Griffin urged the federal government to ensure vaccine stockpiles were adequately supplied, but he doubted a mass vaccination rollout would be needed.

"What we don't want to do is try to get more vaccines when the demand globally has gone up exponentially, and it becomes more challenging."

There was a fine line between responsible stockpiling and hoarding, when other countries could be in far greater need, he said.

How do people catch monkeypox?

They can include rashes, lesions or sores, particularly in areas that are hard to see such as the genitals, anus or anal area or on the face, arms and legs; ulcers, lesions or sores in the mouth; fever, headache, muscle aches, backache, swollen lymph nodes, chills and/or exhaustion.