What Is the Andes Virus? Everything You Need to Know About the Hantavirus Strain on the MV Hondius

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If you’ve been following the news about the MV Hondius — the Dutch cruise ship that has been at the centre of a deadly disease outbreak since April — you’ll have heard a lot about the Andes virus. But what actually is it, how does it spread, and should the rest of us be worried? Here’s everything you need to know, in plain English.

So, What Is the Andes Virus?

The Andes virus is a type of hantavirus — a family of viruses carried by rodents that can cause serious illness in humans. Hantaviruses have been around for decades; they were first identified during the Korean War in the 1950s, and the WHO formally classified them in 1987. There are dozens of different strains found in different parts of the world, but the Andes virus is the one that health experts take most seriously — and for good reason.

The Andes virus is found primarily in South America, particularly in Argentina and Chile. It causes a severe respiratory illness known as Hantavirus Pulmonary Syndrome (HPS), which can progress quickly from flu-like symptoms to full respiratory failure. The CDC identifies it as the most commonly found and most deadly variant in South America.

What Makes It Different From Other Hantaviruses?

Here’s the key thing that sets the Andes virus apart from every other known hantavirus: it is the only strain confirmed to spread between people. Every other hantavirus only passes from infected rodents to humans — never directly from one person to another. The Andes virus can do both.

That said, person-to-person transmission is rare and typically requires close, sustained contact. Research from a 2018 outbreak in the Patagonian village of Epuyén, Argentina, found that the window of peak infectiousness appears to be very short — roughly around the day a person first develops a fever. So while it can spread between people, it is not floating through the air the way measles or flu does. You have to actually be in close contact with someone who is actively symptomatic.

The Andes virus can also spread through respiratory droplets — created when someone coughs, sneezes or talks — as well as through bodily fluids, which is why household members and intimate partners have been disproportionately affected in previous outbreaks.

How Do You Catch It in the First Place?

The primary route of infection is still through rodents. The natural host of the Andes virus is the long-tailed pygmy rice rat, a small rodent found across South America. Humans can become infected by inhaling tiny airborne particles from infected rodent droppings, urine or saliva — something that can happen without any direct contact with the rodent itself.

In the case of the MV Hondius, investigators believe the index case — a Dutch passenger who first showed symptoms — was exposed during a four-month road trip through Argentina, Chile and Uruguay before boarding the ship. A birdwatching excursion in Argentina that some passengers took part in has also been flagged as a possible exposure point.

As one researcher put it: rodents get onto ships, they leave droppings, air currents can aerosolize those particles, and if someone inhales them, the virus can get into the lungs. That’s a known risk on cargo ships and expedition vessels that dock at remote ports.

What Are the Symptoms?

Early symptoms look a lot like a bad flu — fever, headache, muscle aches and stomach problems. This is the tricky part, because there’s nothing in the first phase that would make you think ‘this is hantavirus rather than a regular illness.’ The incubation period can range from four days to six weeks, which makes it even harder to trace.

After this initial phase, the disease can progress rapidly into Hantavirus Pulmonary Syndrome. This is where it becomes life-threatening — patients develop severe shortness of breath, a cough, falling blood pressure and fluid on the lungs. Without intensive medical care, this stage can lead to cardiac shock and death. The case fatality rate for the Andes virus is estimated at 35–40%.

Is There a Treatment or a Vaccine?

Currently, no. There is no approved vaccine and no specific antiviral drug for the Andes virus. Treatment is entirely supportive, which means doctors focus on keeping the body functioning while the immune system fights the infection. This can involve oxygen support, mechanical ventilation, and in serious cases, a technique called ECMO — extracorporeal membrane oxygenation — which temporarily takes over the work of the heart and lungs. Research is underway into both vaccine development and potential antibody treatments, but nothing has been approved for clinical use yet.

How Worried Should We Actually Be?

The honest answer is: not very, unless you’ve been in direct contact with someone who was on board the MV Hondius or spent time in rodent-infested areas of South America recently. The WHO has been clear that the risk to the general public is low, and that the Andes virus is not expected to cause an epidemic.

The Andes virus does not spread easily. It is not airborne in the way that measles or COVID-19 is. Transmission requires either contact with rodent excreta or close physical contact with someone who is actively unwell. International health authorities are actively tracking all passengers who were on board the Hondius, and the UK government has already arranged repatriation flights and mandatory 45-day isolation for British nationals from the ship.

The situation is serious and warrants close monitoring — but it is not cause for public panic.