A French woman who tested positive for hantavirus after she was evacuated from a cruise ship reported symptoms to doctors onboard but was told it was probably just anxiety, the Spanish health minister has said.

Javier Padilla Bernáldez said the woman, who had been travelling on the ship at the centre of a deadly hantavirus outbreak, had been suffering flu-like symptoms but they appeared to be getting better and she did not have a fever. The World Health Organization later said the woman was in a “very critical” condition.

The MV Hondius left the dock in the Canary Island of Tenerife on Monday evening, after 120 people from 23 nations were repatriated over 48 hours in an operation described by Spanish authorities as “complex” and “unprecedented”. About 30 people, the crew and two health workers remained on the ship as it headed to Rotterdam.

Despite the deaths of three people who had been onboard the ship, and eight other confirmed cases, doctors from the European Centre for Disease Prevention and Control and the Spanish foreign health service assessed the French woman and dismissed her symptoms as anxiety or stress, Padilla said.

“They were not thinking that these symptoms were compatible with hantavirus. Why? Because what she was telling [them] was [that she had] an episode of coughing some days ago that had disappeared, and what she was having at that moment was kind of like stress or anxiety or nervousness. So it was not catalogued [as hantavirus],” Padilla said.

Speaking as the ship left Tenerife, Dr Tedros Adhanom Ghebreyesus, the director-general of the WHO, thanked Spain for coming to the aid of those on the vessel and added that the French passenger was now in a “very critical” condition. “Imagine if she stayed longer in the ship,” he said.

There was “nothing to fear” for the people in the countries that received passengers, he continued, and hoped they would show “compassion and your solidarity to your citizens”.

The French woman was one of five French passengers who disembarked from the MV Hondius in Tenerife on Sunday before being flown to a hospital in Paris.

The French health minister, Stéphanie Rist, said the woman had started to feel very unwell on Sunday night and “tests came back positive”. Rist told France Inter radio: “Unfortunately, her symptoms worsened overnight.” She is being treated in a specialised infectious diseases unit of a hospital in Paris.

Personnel in full-body protective gear and breathing masks began escorting the travellers from ship to shore in Tenerife in the Canary Islands on Sunday.

The WHO and the Spanish government had reassured the public on Saturday night that all 149 passengers and crew were asymptomatic of the infection, which causes flu-like symptoms and can lead to respiratory failure.

Padilla defended the approach saying there were likely to be some cases without severe symptoms and that was why all passengers and crew were recommended to isolate for 45 days since they were last exposed, which has been agreed as 6 May.

In Spain, those evacuated from the ship have been taken to a military hospital, while 22 British people, one German and one Japanese person have been taken to Arrowe Park hospital in Merseyside for quarantining and tests.

Each of the 23 countries that passengers and crew originated from are responsible for deciding their own measures.

“I think that it cannot be said that you have disembarked them and now they are spreading the situation,” said Padilla.

“What has happened with France, I think it’s a case of good practice in public health management of an epidemiological alert because if we were thinking that it was not a possibility that no one was able to develop a disease, we would not be quarantining the people.”

He said that the woman’s condition had deteriorated between the ship and the plane. “It is not that the patient was feeling bad and she was saying, ‘OK, I’m not going to say anything because I want to be on the plane’. It was like: ‘OK, we have measured your temperature, it was not fever, afterwards you have been on the plane, it has taken off, you have started feeling bad, we have measured your temperature and it was fever.’”

An American passenger who was flown to Nebraska along with 16 others on Sunday evening also tested positive but had no symptoms. The US health department said one American national evacuated from the ship had tested positive for the Andes strain – the only hantavirus strain that is transmissible between humans – and another had “mild symptoms”. Both the WHO and the Spanish government said the positive was not strong enough to be conclusive and have not counted the US case in the official figures.

Padilla said passengers could not have been tested onboard the vessel because there were no rapid PCR tests for hantavirus available. Any testing would have involved flying samples to Madrid to a specialist lab, a process that would have taken 24 hours. Those delays would have made it impossible to rescue those on board due to a forecast of extremely high winds from Monday evening, which were due to be “hell” on Tuesday, he said.

Those high winds meant the ship was forced to dock on Monday afternoon for safety reasons. This was something the Spanish government had insisted would not happen, after the president of the Canary Islands, Fernando Clavijo, argued that docking the ship increased the possibility that rats carrying hantavirus would spread to the land, putting local people at risk.

It is not yet known the cause of the ship’s outbreak but it is thought to have been spread person-to-person and brought onboard the ship after a birdwatching trip in Argentina by a Dutch husband and wife who became the first fatalities.

A spokesperson for Clavijo told the Guardian on Monday evening that the president did not think enough precautions were taken to stop the spread of the virus but that he hoped “everything ends fine for the passengers and the operators”.

No vaccines or specific treatments exist for hantavirus, which is endemic in Argentina, from where the ship departed in April. But health officials have said the risk for global public health is low and have played down comparisons with the Covid-19 pandemic.

Health authorities in several countries have been tracking passengers who had already left the ship, plus anyone who may have come into contact with them.

A flight that was intended to fly passengers back to Australia was abandoned because of timing problems. The six passengers who were due to travel on it – four Australians, one Briton who is resident in Australia, and a New Zealand national – will instead return home via one of the Netherlands flights.

The ship will then depart for the Netherlands with the 26 crew members on Monday evening.