Health chiefs are racing to contain a hantavirus outbreak after British cruise passengers were flown back to the UK and placed into quarantine under strict biosecurity measures.

Twenty-two evacuees from the MV Hondius were rushed into isolation after landing in Manchester on a charter flight from Tenerife, where the virus-linked cruise ship had been held.

The passengers - 20 Britons, one German resident and one Japanese national - were transferred under strict infection control measures to Arrowe Park Hospital on the Wirral, Merseyside, where they are undergoing 72 hours of clinical monitoring before facing up to 45 days of further isolation.

The hospital famously housed some of Britain's first Covid patients during the early stages of the pandemic in 2020.

Some passengers could later be seen wearing blue medical gowns and facemasks as they were escorted onto waiting coaches outside the hospital.

Passengers, drivers, medical teams and flight crews all wore PPE throughout the repatriation operation, with travellers transported directly from the airport to specialist quarantine accommodation.

Officials said all evacuees are currently asymptomatic but are being closely monitored as a precaution.

Within 72 hours, infectious disease specialists from the NHS and the UK Health Security Agency (UKHSA) will carry out clinical assessments and testing before deciding where each passenger should complete their isolation.

During this period, passengers will receive daily contact from UKHSA health protection teams to check for symptoms and ensure compliance with isolation guidance.

Officials are also tracing anyone considered to have had high-risk contact with infected passengers during the multinational evacuation effort.

But the developments have inevitably raised questions about whether the outbreak could spread further. So what are health chiefs actually doing to stop it spiralling? 

Covid-style quarantine facility 

Passengers are now being housed in Covid-era quarantine flats at Arrowe Park Hospital.

The self-contained apartments - complete with bedrooms, bathrooms, kitchens and living areas - were previously used during the early Covid response in 2020.

Janelle Holmes, chief executive of Wirral University Teaching Hospital NHS Foundation Trust, said welfare checks would be carried out on all evacuees.

She confirmed there was no impact on normal hospital services and that none of the passengers had shown symptoms on arrival.

If anyone becomes unwell, they will be transferred to Royal Liverpool University Hospital's specialist Tropical and Infectious Diseases Unit.

72-hour monitoring and up to 45-day isolation

Following the initial 72-hour monitoring period, officials will decide whether passengers can continue their isolation at home or at another secure facility.

They will not be allowed to use public transport and will remain under regular testing and health monitoring throughout the isolation period of up to 45 days.

The UK Government said all evacuees will receive support, including welfare assistance and supplies, while in isolation.

Public health minister Sharon Hodgson said: 'None of the passengers are symptomatic but we will monitor them closely over the next 72 hours at the hospital, as part of a precautionary isolation period.'

She added that the combined measures meant the risk to the public remained 'extremely low'.

Devi Sridhar, Professor of Global Public Health from the University of Edinburgh, said: 'Over the coming days, it's likely that others on the ship will test positive for hantavirus. 

'What's crucial is that all passengers on the ship self-isolate for 45 days, especially. 

'Those most at risk are people they live with and their family and friends - basically close contacts. 

'Public health authorities need to make sure they follow quarantine for the next 45 days - it's super important to ensure secondary contacts don't become infected.

'We won't know for days, or even weeks, how many more cases could emerge of hantavirus linked to the cruise ship. 

'The long incubation period means we need to continue public health efforts to isolate symptomatic patients and quarantine contacts. We also need to be careful with overconfidence or assumptions until evidence becomes clear.'

Why experts are worried about the Andes strain 

Hantavirus is usually spread through exposure to infected rodents' droppings, urine or saliva.

However, scientists are closely monitoring this outbreak because the Andes strain has in rare cases, shown limited human-to-human transmission in confined environments.

Professor Robin May, chief scientific officer at UKHSA, said the virus is very different from Covid and stressed the risk to the public remains extremely low.

He said: 'We think the virus primarily spreads only from people who have symptoms.

'The cruise ship setting is a very close living situation, so perhaps an area in which spread is more likely.

'It's definitely not the same as people who might pass someone in the street, for example. So the risk there is essentially negligible.'

Rowland Kao, Professor of Veterinary Epidemiology and Data Science, said: 'The incubation period for Andes virus in humans is very long (listed as nine to 40 days), which would suggest that, long after infection, there will be some risk of onward transmission.

'As you know, Andes virus is also unusual in that the evidence is that human-to-human transmission can occur in conditions of very close contact.

'However because it is only close contact, the overall risk to the general public is itself very low, and the probability of sustained transmission from person-to-person therefore even lower.

'So while anyone who has been on the affected ship should be aware of the symptoms and get tested should they display it, for anyone other than a potential close contact, the risks are negligible.' 

Instead, the expert believes a bigger threat of a nationwide outbreak would be connected to infected rodents reaching the UK. 

Professor Kao said: 'The main risk of it coming onshore by other means is through infected rodents. 

'Reports suggest it is more likely transmission occurred from rodents onshore either before the cruise or during one of its South Atlantic stops. If so, the long incubation period may make the exact point of infection difficult to determine.' 

Fresh suspected cases reported among overseas evacuees 

Concern has grown after further suspected cases were reported among overseas passengers linked to the ship.

One American passenger tested positive after arrival in the United States, while another later developed symptoms, US health officials said.

A French passenger also developed symptoms during a repatriation flight to Paris, prompting isolation measures on arrival.

The outbreak is understood to involve the Andes strain of hantavirus - one of the few forms that can, in rare circumstances, spread in very close-contact environments.

Health officials stress, however, that the risk to the general public remains extremely low.

Military medics deployed to remote island 

The response has also reached the remote British overseas territory of Tristan da Cunha, where one suspected British case is being supported.

Six paratroopers, an RAF consultant and an Army nurse from 16 Air Assault Brigade were parachuted onto the island with medical supplies and oxygen.

The Ministry of Defence said it was the first time UK military medical personnel had been deployed by parachute to the territory.

The island is normally accessible only by sea, making emergency intervention extremely difficult.

What happens next for the MV Hondius 

The MV Hondius arrived in Tenerife, where passengers from 19 nationalities were evacuated in stages.

Spanish authorities ferried passengers ashore by small boat before transferring them onto charter flights organised by their home countries.

Passengers were instructed to leave most luggage onboard and were only permitted essential items such as passports and phones.

Around 30 crew members, a Dutch nurse and the body of a passenger who died onboard remain on the vessel.

The ship will now sail to Rotterdam, where it will undergo disinfection procedures.