The head of the World Health Organization has warned countries to prepare for more hantavirus cases after the outbreak onboard the MV Hondius, and thanked Spain for the “compassion and solidarity” it had shown by taking in the stricken cruise ship and evacuating its passengers and crew.

Tedros Adhanom Ghebreyesus urged countries to follow the WHO’s advice and recommendations, which include a 42-day quarantine and constant monitoring of high-risk contacts.

“At the moment, there is no sign that we are seeing the start of a larger outbreak, but of course the situation could change and, given the long incubation period of the virus, it’s possible we might see more cases in the coming weeks,” he told a press conference in Madrid on Tuesday.

The MV Hondius, which was sailing from Argentina to Cape Verde, found itself at the centre of the outbreak after three passengers – a Dutch couple and a German national – died from the virus. Although usually spread by wild rodents, hantavirus can be transmitted person-to-person in rare cases of close contact.

The WHO has so far confirmed nine cases of the Andes strain of the virus, among them a French woman and an American national who tested positive after being evacuated from the ship.

Tedros, who was speaking alongside Spain’s prime minister, Pedro Sánchez, said more cases were likely to appear because of the degree of interaction between the passengers onboard the ship before the alarm was raised and the first case confirmed in a passenger on 2 May.

“We would expect more cases because, as you may remember, the index case – the first case in the ship was on 6 April … [and] there was a lot of interaction, actually, with the passengers. And as you know, the incubation period is also six to eight weeks.

“So because of the interaction while they were still in the ship – especially before they started taking some infectious prevention measures – because of the interaction, we would expect more cases because of some of what happened during the travel.”

Tedros said individual countries were now responsible for their citizens after the evacuation, adding: “I hope they will take care of the patients and the passengers, helping them and also protecting their citizens as well. That’s what we expect.”

The WHO chief also paid tribute to the Spanish government and the people of Spain for responding to the plight of those onboard the ship after authorities in Cape Verde refused it permission to dock. More than 120 passengers and crew members were evacuated from Tenerife in a carefully coordinated operation on Sunday and Monday.

“I’d like to thank Spain and, especially, Prime Minister Pedro Sánchez, for the outstanding leadership and coordination,” he said. “I know this is a model – and I hope other countries also learn from this – not just the obligation part but the compassion and solidarity that Spain has shown.” In a “divided and divisive world”, he added, “kindness and taking care of each other” were important.

Sánchez echoed the sentiment, saying: “This world doesn’t need more selfishness, nor more fear. What it needs is countries that show solidarity and want to move forward.”

The prime minister also offered his condolences once again to the family of a Guardia Civil officer who died of a heart attack while taking part in the evacuation on Sunday.

Despite objections from the regional government of the Canary Islands, Spain’s central government allowed the MV Hondius to anchor in port in Tenerife – and then, briefly, to dock – as it oversaw the evacuation operation.

The final two planes carrying passengers and crew left the Canary island on Monday night and arrived in the Netherlands early on Tuesday. The MV Hondius, which refuelled and restocked in Tenerife, is now sailing back to port in Rotterdam with a crew of 25 as well as a doctor and nurse.