A worldwide hunt is underway for passengers who escaped the disease–struck MV Hondius after it was plagued by a rat–borne virus.

Questions have been raised over the symptoms of the deadly hantavirus variant, how contagious it is – and even whether it can be caught at a cruise ship buffet.

Here we answer some of the most pressing thoughts on the minds of people across the world following the death of three passengers on the luxury boat as it travelled from the Argentinian city of Ushuaia towards Cape Verde in Africa.

More than 20 Britons on board the doomed cruise ship will be repatriated as soon as possible – and face being quarantined for up to eight weeks. 

Despite the outbreak having sparked international alarm, the World Health Organisation has insisted the situation does not have similarities with the start of the Covid pandemic.

'This is not the next Covid, but it is a serious infectious disease,' WHO's top epidemic expert Maria Van Kerkhove said. 'Most people will never be exposed to this.'

How do you get it?

Hantavirus is found in rodents and can be passed on to humans in areas where they may have nested, like barns and rural holiday homes.

Rodents carrying the virus shed it in their urine, faeces and saliva, which can become airborne and inhaled by humans. Contaminated food, or bites or scratches, can also lead to hantavirus being transmitted, as can cleaning out the cages of pet rodents.

The strain implicated in the cruise ship outbreak is likely to have come from the long–tailed pygmy rice rat, in which it is endemic.

What are the symptoms?

Symptoms typically occur between two to four weeks after someone has been exposed to the virus. While there are believed to be 'about 100,000 to 200,000 cases globally, it is thought there are more infections that go unreported because many will be mild, [and] may not have any symptoms at all,' explains Professor Jonathan Ball, professor of molecular virology at Liverpool School of Tropical Medicine.

Symptoms, including fever, aches, nausea and vomiting, can be 'very general' and apply to many ailments, making it hard to identify hantavirus in its early stages.

If the condition progresses, however, it can result in one of two serious diseases: hantavirus pulmonary syndrome (HPS), where acute respiratory failure leads to fluid filling the lungs (the cause of death for Betsy Arakawa, wife of Oscar–winning actor Gene Hackman, last year). Or haemorrhagic fever with renal syndrome (HFRS), which results in acute kidney failure and internal bleeding.

How contagious is it?

'Hantavirus doesn't spread particularly effectively between humans,' says Professor Ball. 'It's a relatively rare infection and the number of human–to–human infections that have been reported have been very low. So, it's difficult to give an exact number, but it is very poor at transmitting between humans.' In an outbreak in Argentina, in 2018–19, three people who came into contact with infected rodents spread hantavirus to 34 others, 11 of whom died.

Could you catch it at a cruise ship breakfast buffet?

For hantavirus to be passed from human to human usually requires sustained exposure when the person is infectious, such as in family homes, Professor Ball says, where 'people are living very close to one another, sharing rooms for long periods of time'. That makes it unlikely you could catch it in the queue for an omelette.

'If we take the current example of the cruise ship,' says Professor Ball, 'if somebody's sharing a cabin, for example, for a long period of time, then that would increase your risk. If you just happen to pass somebody who's infected, it's probably a very, very low risk.'

How fatal is it?

Different strains of hantavirus (there are nearly 40) have different fatality rates. According to the World Health Organisation, it leads to death in up to 15 per cent of cases in Europe and Asia, where strains tend to cause kidney complications, and up to 50 per cent in the Americas, where hantavirus is more likely to cause cardiopulmonary symptoms. If the cruise ship strain was contracted in Argentina as suspected, it's probably the more dangerous kind.

Are certain countries more at risk, and should I avoid them for holidays?

Professor Ball says there is no need to avoid certain parts of the world. Instead, travellers should be vigilant for signs of rodent nests and behaviours that could encourage rodent activity. Hikers in shared overnight shelters, for example, sometimes inadvertently leave food remnants behind. 'That will encourage rodents, and then those rodents may well leave droppings, and then the next people who come into that shelter could potentially be exposed.'

Should I cancel my summer cruise?

'Do not cancel your holiday because of hantavirus,' advises Rob Staines, an independent travel expert. 'It is very early days and there is far more risk of your flight being cancelled due to weather conditions than dangers posed by a virus.'

What treatment is available?

Patients may receive supportive care, says Professor Ball – 'so if you've got breathing difficulties, you'll get help with breathing'. That may be additional oxygen or it may be where you have a tube inserted into your airways and you're physically helped to breathe.'

There are currently no licensed drugs for hantavirus, he adds, 'but there are what we call 'compassionate use' drugs available', such as ribavirin and favipiravir, which are antiviral medications.

There has been some research to show that these may help to prevent serious disease among those who contract hantavirus, but 'there's insufficient evidence, which is why these treatments aren't yet licensed'.

Will travel insurance cover me if I catch hantavirus overseas?

Staines says that most policies do not cover specific virus outbreaks, particularly since the Covid pandemic. 'Some policies may cover trip cancellation if you are personally unable to travel due to illness but nearly all will require specific documentation. Speak to your insurer if you have concerns.'

Are some people more at risk?

Yes, says Professor Ball. Advanced age and underlying health conditions such as circulation or breathing problems can increase the risk of developing hantavirus.

Can you tell if rats have the virus?

No – hantaviruses do not make rats unwell, or even symptomatic. 'The rodent becomes what we call persistently infected, so they can shed the virus pretty much throughout its life without any ill effect themselves,' Professor Ball says.

Could I get it from a rat at home?

In the UK, hantavirus is associated with pet rats. Stephen Wales, founder of Bespoke Pest Control, says: 'In the UK the risk is genuinely low. The cases we've seen here have mostly been linked to pet rats or rats bred for reptile feeding, not your typical household infestation.

'The risk stays low when it's dealt with professionally. Where it becomes a problem is when people disturb dried rodent material themselves, clearing a loft, sweeping under kitchen units without protection' as this can make the virus airborne and more easily transmissible.

What other species is it found in?

Hantaviruses can be found in mice, rats and voles. Indeed Professor Ball says that among field voles 'we recently recovered hantaviruses from the UK that hadn't been recognised previously, but we have no evidence that voles can cause human infection'.

Why are we only hearing of hantavirus now?

HFRS was first found in US soldiers fighting in Korea in the 1950s (known as Seoul hantavirus), while HPS cases have been tracked in the US since 1993.

'It takes an exceptional set of circumstances to make [an outbreak like] this happen, and those have arisen just by chance with a perfect storm this time,' says Chris Smith, consultant virologist at Addenbrooke's Hospital and presenter of the Naked Scientists podcast. Of this current outbreak, he adds, 'I think it's just a case of bad luck.'

Will hantavirus become more common now?

We are seeing more emerging infections like hantavirus because 'the factors that make them jump from one species to another are intensifying', Smith says.

'There are more of us living in higher density [situations], which facilitates spread and conflict with nature where the infections are. There are more of us who are mobile around the planet, and if we move frequently from one place to another, we take our infections with us.'

Will hantavirus be the next Covid?

Thankfully not, says Professor Ball – 'unless the virus mutates, and that's highly unlikely'.