EXPLAINER: How dangerous is hantavirus?
A serious but limited outbreak of hantavirus on the cruise ship MV Hondius has has left three people dead and several others infected. Professor Søren Riis Paludan explains the risk of infection and the danger posed by the virus.
Professor Søren Riis Paludan
Søren Riis Paludan is professor of molecular virology and immunology at the Department of Biomedicine, Aarhus University.
He is also head of the Center for Immunology of Viral Infections, CiViA.
His research focuses in particular on how the body’s innate immune system detects and fights viral infections.
How do you become infected with hantavirus?
“Hantavirus is primarily found in rodents - especially mice and rats. Infection typically occurs when people ingest or inhale urine and droppings from the rodents; it can also happen through bites. Hanta is a large group of viruses, and only one of the hantavirus variants can spread between humans.”
What happens when you become ill with hantavirus?
“Hantavirus infection often begins as a non-specific viral illness with high fever, headache, muscle pain, dizziness, nausea, vomiting, diarrhoea or abdominal pain. For that reason, the illness can initially resemble many other viral infections. In some people, it develops into a serious condition. Depending on the type of hantavirus, it may particularly affect the lungs or the kidneys. The incubation period can vary from one to six weeks, and the disease is confirmed by detecting antibodies against hantavirus in the blood.”
How dangerous is hantavirus?
“The risk depends heavily on the virus variant and geography. The South American hantavirus variant ‘Andes’ - which can spread between humans - has a fatality rate of up to 50 percent. It is serious even if you are healthy and fit. Northern European infections are far less deadly. The risk for the individual depends on the immune response, the dose you are exposed to, and your general physiological condition.”
Is there a vaccine or cure?
“Hantavirus was discovered as early as the 1950s, but there is no widely used and effective vaccine against hantavirus, and no vaccine is approved in the EU. There is also no actual cure or approved specific antiviral treatment for hantavirus infection. Treatment is primarily supportive, for example oxygen or ventilator treatment, circulatory support, fluid therapy and, if necessary, dialysis. In some studies, the drug ribavirin has shown beneficial effects when used early in the treatment of hantavirus with renal syndrome.”
What can you do to avoid the disease?
“If we are talking about transmission from animals to humans, it is about maintaining good hygiene, especially when travelling in places such as Asia or South America. You should avoid contact with mouse and rat droppings, and make sure food is properly prepared. Human-to-human transmission occurs rarely and is associated with close and prolonged contact.”
Can you get hantavirus in Denmark?
“Yes, for example if you come into contact with infected mouse droppings. In Denmark, the typical variant is called Puumala virus, and it is carried by the bank vole. But very few people get a hantavirus infection in Denmark.”
Is hantavirus the next COVID pandemic?
“No, because it does not spread particularly efficiently between humans. Broadly speaking, you have to touch each other or touch something that is contaminated before the virus is transmitted. To have pandemic potential, a virus must spread very efficiently; it typically has to be airborne.
Hantavirus and COVID are not in the same virus family. There are plenty of micro-outbreaks of viral infections globally - so many that one could write a news story about them every day. As the world’s population grows, encounters between humans and animals create more opportunities for spillover events from animals to humans. But outbreaks almost always die out quickly and very rarely become an epidemic or pandemic. Hantavirus is getting attention right now because there is an outbreak on a cruise ship, but it does not have the potential to become a worldwide pandemic.”
Will hantavirus infections increase?
“The latest figures for hantavirus infections show 1,885 reported cases in Europe in 2023. We may perhaps expect a small increase in reported cases worldwide, but it is not going to explode. Whether the increase is due to a small outbreak, or solely due to increased attention because it is currently affecting wealthy people on cruise holidays, is difficult to say.”
Can hantavirus mutate into something more dangerous?
“The variants with a high fatality rate of 30–50 percent are, of course, already dangerous for the individual who becomes infected. But the virus-caused disease will only become more widespread, and therefore a greater public health threat, if the virus mutates into something more contagious. However, that is very unlikely.”
Contact
Professor Søren Riis Paludan
Aarhus University, Department of Biomedicine
Email: srp@biomed.au.dk
Mobile: 28 99 20 66
This text is machine translated