Canadian officials said on Saturday that one of the four Canadians currently quarantining in British Columbia after being exposed to the hantavirus while on board the cruise ship where the outbreak occurred has presumptively tested positive.

Speaking at news conference, Dr Bonnie Henry, British Columbia’s provincial health officer, said the individual developed mild symptoms, including fever and headache, two days ago, and that the individual and their partner, who had also been on board the cruise ship where they had been isolating together, were transferred to a hospital in Victoria for assessment and testing.

Henry said that on late Friday evening the test results for the individual who had been experiencing mild symptoms came back positive, though she stressed that the results were currently “what we call a presumptive positive” and that the samples have been sent to the national microbiology lab in Winnipeg for confirmatory testing. Results from those tests are expected to be confirmed over the course of the weekend, Henry said.

“Clearly this is not what we hoped for, but it is what we planned for,” Henry said.

“The patient is stable, and their symptoms remain mild at this point,” Henry said. “And they are still in hospital, in isolation, being monitored and receiving care as needed.”

The patient’s partner tested negative, but will also remain in hospital for further monitoring and assessment, Henry said.

Out of what Henry described as “an abundance of caution”, the third individual who had been isolating in the same lodging has also been transferred to hospital for monitoring. The fourth person continues to isolate at home under daily observation, she said.

The four Canadians who had been on board the Dutch cruise ship MV Hondius, where the hantavirus outbreak occurred, arrived in Victoria on 10 May, Henry said, adding that on arrival, all four of them were assessed and none of them had any symptoms at that time.

They were transferred directly to lodgings to begin a period of quarantine for a minimum of 21 days.

The World Health Organization has recommended a 42-day quarantine period.

Since 11 April, three people who were on board the cruise ship have died of suspected hantavirus infections of hantavirus, including a Dutch couple and a German woman.