A Sunshine Coast man who has been in quarantine on the Diamond Princess cruise ship has tested positive for coronavirus and will be separated from his wife.

Paul and Coralie Williamson have been in isolation on board the stricken ship, docked off Yokohama in Japan, since February 4.

Mr Williamson said he would be transferred to hospital and his wife would "remain on board at this stage".

It is unfortunate timing for the couple.

Paul and Coralie Williamson's room, which has a bathroom and balcony. ( Supplied: Paul Williamson )

The official quarantine period aboard the ship finishes today and the Federal Government has arranged a charter flight to evacuate the Australians on board, leaving about midnight.

Prime Minister Scott Morrison said of the about 220 Australians onboard, 36 have tested positive. Another 15 have decided not to return on the chartered flight.

"The predominant reason for that is they are staying in many cases with family members who have actually contracted the virus and are receiving medical attention in Japan," he said.

"But the good news is we will be bringing [the others] home today."

Mr Williamson said there was still a lot of questions about what would happen to his wife.

"We are prioritising our needs at the moment," he said.

The couple had been extremely careful during their containment.

Their room had an ensuite and balcony, unlike others on the ship, and they declined invitations to get fresh air on the deck in an effort to limit their exposure to the virus.

The Diamond Princess at Yokohama Port, with thousands onboard. ( AP via Kyodo News: Sadayuki Goto )

Those who did go were asked to stay 2 metres away from other passengers and crew.

Monash University professor of infectious diseases, Allen Cheng, said the virus was most likely spreading through poor hand hygiene and contaminated food trays.

Although the Williamsons isolated themselves, the crew are living much closer together.

The decision to keep the travellers onboard the ship was the wrong one, Professor Cheng said.

"There are potential infections in the crew and the crew don't have rooms like the passengers rooms," he said.

"Clearly there's been a problem with the quarantine procedures on the ship."

The Williamsons said their extended isolation had been trying on their mental health. ( Facebook: Paul Williamson )

During previous interviews with the ABC, Mr Williamson said they were going stir crazy aboard the ship.

To keep mentally healthy, they had decided to ration their movie stash and used their Fitbits to track their exercise in their cramped quarters.

Passengers have been unable to interact with one another, with the only outside human contact coming from staff members delivering food to the rooms.

"It is surreal, it's quite bizarre," Mr Williamson, a former school principal, said earlier this month.

Of 2,666 guests and 1,045 crew on the ship, about 542 people have caught the virus.

The Australians being evacuated will fly to Darwin, where they will be quarantined for another fortnight.

The Government has said passengers will be tested for coronavirus five times throughout the journey; once on the ship, twice during the flight, once at the RAAF base after they land, and then when they arrive in Darwin.

"At the end of the day the safety of Australians, the health of Australians, has to be put first and that's what we've done," Mr Morrison said.