What is Hantavirus and how is it spread?

A deadly outbreak of hantavirus aboard a Dutch cruise ship in the Atlantic Ocean has thrust a rare but lethal family of viruses back into the global spotlight. Three passengers have died, at least six cases have been identified, and the ship (MV Hondius) remains at sea as international health authorities scramble to respond. Here is what you need to know about hantavirus.

What Is Hantavirus?

Hantavirus is a family of viruses (of the family Hantaviridae) that are carried primarily by rodents such as rats and mice. First formally identified in the 1950s in Korea, hantaviruses are found across the globe, with different strains prevalent in different regions.

In the Americas, hantavirus is best known for causing Hantavirus Pulmonary Syndrome (HPS), also called Hantavirus Cardiopulmonary Syndrome (HCPS), a severe and often fatal disease attacking the lungs and heart.

In Europe and Asia, different strains tend to cause Hemorrhagic Fever with Renal Syndrome (HFRS), which primarily damages the kidneys and blood vessels. The strain implicated in the current cruise ship outbreak is believed to be the Andes virus, a South American variant with a particular characteristic of spreading between humans.

How does Hantavirus spread?

The primary route of infection is through rodents. Infected animals shed the virus in their urine, faeces, and saliva. Humans become infected most commonly by inhaling airborne particles. These particles are of microscopic droplets or dust contaminated by dried rodent droppings or nesting materials that have been disturbed.

Person-to-person transmission is uncommon for most hantavirus strains. However, the Andes virus is an exception. The World Health Organisation (WHO) is currently investigating whether the cruise ship outbreak may involve human-to-human transmission, as several passengers who fell ill had no obvious independent exposure to rodents.

What are the symptoms?

Hantavirus has an incubation period of roughly one to eight weeks, meaning infected individuals may not show signs of illness for weeks after exposure. This delay complicates early detection and contact tracing.

Symptoms of Hantavirus Pulmonary Syndrome typically unfold in two phases:

Days 1–5: Fever, chills, deep muscle aches (particularly in the thighs, hips and back), headache, fatigue, dizziness, and gastrointestinal symptoms such as nausea, vomiting and abdominal pain. These early symptoms closely mimic influenza, making diagnosis difficult.

Days 4–10: The disease can progress rapidly and without warning to coughing, severe shortness of breath, and acute respiratory distress as the lungs fill with fluid. Shock and heart complications can follow. This stage is a medical emergency.

For HFRS, the later stages involve low blood pressure, bleeding disorders, and acute kidney failure rather than lung complications.

Who is most at risk?

Anyone can contract hantavirus if exposed to infected rodents or their excretions. However, people who spend time in environments with high rodent populations — such as campers, hikers, farmers, forestry workers, and those in rural areas of South America — face a higher risk.

Severe illness and death can occur in otherwise healthy adults. The current outbreak aboard the MV Hondius has claimed three lives and left at least one passenger critically ill, demonstrating the virus’s capacity to be rapidly fatal even in the modern era.

Health authorities have emphasised that the general public is at low risk. The World Health Organisation currently assesses the risk to the global population as low, and there is no evidence that the virus is spreading beyond the defined cluster of cases.

Is there a treatment?

There is currently no specific antiviral drug or vaccine approved for hantavirus. Treatment is entirely supportive, meaning it focuses on keeping the patient alive and stable while their immune system fights the infection.

Patients with severe HPS typically require intensive care, including:

• Close monitoring of respiratory and cardiac function
• Oxygen therapy and mechanical ventilation
• Management of fluid levels in the lungs
• Treatment of shock and multi-organ complications

Early hospitalisation dramatically improves survival odds. Patients who deteriorate to the full respiratory phase of HPS face a case fatality rate that can exceed 30% even with optimal care.