An Adelaide woman has been stranded on a cruise ship in north-eastern Brazil for almost a week after a passenger on board tested positive for coronavirus.

Key points: Bobbie Roberts said the ship was not testing any passengers despite the positive test

Bobbie Roberts said the ship was not testing any passengers despite the positive test All passengers have been in isolation since Thursday

All passengers have been in isolation since Thursday Ms Roberts claims passengers have been let down by management

Bobbie Roberts said she fears the virus could have spread throughout the ship, but there's no way of telling because testing has been "almost non-existent".

"We were supposed to be tested by temperature three times a day … but the first temperature check we had was yesterday," Ms Roberts said.

Ms Robert's Silver Shadow cruise ship departed Rio de Janeiro on March 7, stopped in Salvador de Bahia before making its way to Recife, where it is now docked.

The ship has 609 people on board, including the crew, and the passengers have been kept in isolation since last Thursday when a passenger showed symptoms of coronavirus.

"I was sitting just looking out the window of the dining room, and I'm watching all these people in gowns outside," she said.

"The waiter comes along and I said, 'What's going on out there?' And he said, 'Oh, well, someone's been taken off the ship, sick'."

Staff on board later confirmed the passenger — a 78-year-old man from Canada — had tested positive for COVID-19.

Ms Roberts claimed passengers have been left in the dark by the ship's management.

A spokesperson from the cruise ship's parent company Silversea confirmed to the ABC that two passengers were taken off the ship in Brazil.

"We can confirm that two guests aboard the Silver Shadow have been medically disembarked in Recife, Brazil, and one has tested positive for COVID-19, while the second has tested negative," the spokesperson said.

"On behalf of our guests, we are in close coordination with the governments and local health authorities to determine next best steps.

"We have asked guests on the ships to temporarily remain in their cabins in accordance with our medical isolation protocols.

"Our top priority is to ensure the health and comfort of our guests and crew, and we thank our guests for their patience and understanding as this issue affects them and so many around the world."

Cruise a 'trip of a lifetime' birthday present

Ms Roberts said she has been cooped up inside her room for days, with strict quarantine measures enacted on board.

It has been a heartbreaking blow for Ms Roberts, who purchased "the trip of a lifetime" more than 12 months ago as a present for her 71st birthday.

"I was hoping we would be tested properly, all of us [passengers], so we would then be able to move on with the cruise, virus-free," she said.

A beach in Rio de Janeiro, Brazil, which Ms Roberts visited earlier on the cruise. ( Supplied: Bobbie Roberts )

Ms Roberts is travelling alone, and says she's feeling "really down" and lonely in isolation.

"We can't see anyone, [the staff] are decked out in hazmat suits and leave your meal at the door, it's just awful."

The only contact Ms Roberts has on the ship is a lady from Sydney who she befriended on the first day of the cruise.

"She calls me every day to make sure I'm all right, I don't know what I would have done without her," she said.

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It has been a small comfort for the soon-to-be grandma from Port Noarlunga, who is now desperate to get home.

She has a grandson due in a couple of weeks and is also worried about her 92-year-old mother, who suffers from a heart condition and relies on Ms Roberts for care.

Company 'did not clarify refund policy', Ms Roberts claims

Ms Roberts said she had regular contact with Silversea's Australian agent right up until the day she left Australia for Rio and was assured the cruise would be safe during the coronavirus crisis.

She says she knew about the problems on the Diamond Princess cruise ship in Japan but thought her cruise would have a plan to prevent the same thing from happening.

"I assumed Silversea would have weighed up the risks and would have told us not to go if it was too dangerous," Ms Roberts said.

"I thought they'd have a better handle of it."

She said despite pressing the company's Australian agent about options for refunds or credits in the lead up to the trip, none were made known to her.

"I was told refunds were not part of the ship's policy," Ms Roberts said.

"I sent an email the day before I left saying 'I'm really worried, I'm really scared and I don't know what to do, because if I cancel, I'll lose all this money'."

"And I was not offered anything at that stage … I have since found out the company made a decree that people could cancel within 48 hours."

In a statement on the Silversea website on March 6, the company said cancellations could be made up to two days before departure on all voyages departing before July 31.

"The new 'Cruise with Confidence' policy will enable travellers to cancel their sailings as late as two days before departure, providing guests with a future cruise credit," the statement read.

A few days later, Silversea released another statement saying it would protect travel agent commission "on all bookings cancelled under the Cruise with Confidence program set to depart between March 9 and July 31, 2020".

Stuck in limbo as authorities liaise with government

Ms Roberts contacted the Australian Emergency Consular Assistance line and the Australian embassy in Brazil for help.

She said she received an email back saying the Australian Embassy and Department of Foreign Affairs and Trade (DFAT) were liaising with state and federal Brazilian government authorities and Silversea.

"While the company and government authorities are actively considering options, we understand that no decision has been made at this point on possible next steps," the email from DFAT read.

"In the meantime, we would encourage you to continue talking to the cruise ship authorities and, if appropriate, the travel insurer, to see what might be possible."