Hantavirus has emerged from near-obscurity into global headlines following the outbreak aboard the MV Hondius, a luxury expedition ship in the Atlantic where three passengers have died and eight have been infected. Here is everything you need to know about the virus, how it spreads, why the Andes strain is particularly alarming, and what the outbreak means.
What is hantavirus?
Hantavirus is a family of viruses carried primarily by rodents — mice, rats, and voles — that can infect humans who come into contact with infected animals or their droppings, urine, or saliva. The virus was first identified following an outbreak among US soldiers during the Korean War in the 1950s, though it was formally named and characterised only in 1993 after a cluster of unexplained deaths in the American Southwest drew scientific attention.
There are multiple strains of hantavirus, broadly classified into two groups based on the disease they cause. The Old World strains, found across Europe and Asia, primarily cause haemorrhagic fever with renal syndrome — a severe kidney disease. The New World strains, found in the Americas, cause hantavirus pulmonary syndrome, a condition that attacks the lungs and can kill within days of symptom onset.
What is the Andes strain and why is it especially dangerous?
The strain identified on the MV Hondius is the Andes hantavirus, first described in Argentina and Chile in the 1990s. It is responsible for causing hantavirus pulmonary syndrome and carries a case fatality rate estimated at 25-35%, making it one of the deadlier infectious agents known to science.
What makes the Andes strain uniquely alarming within the hantavirus family is that it is the only strain with confirmed human-to-human transmission. Every other known strain of hantavirus spreads exclusively from rodents to humans — person-to-person spread is not possible. The Andes strain breaks this rule. It can pass between people, though only through sustained, very close physical contact such as sharing a sleeping space or providing unprotected medical care to an infected person. It does not spread through casual contact, airborne particles in ordinary settings, or contaminated food or water.
How does hantavirus infect humans?
In the vast majority of cases globally, hantavirus infection occurs when a person inhales microscopic particles of infected rodent droppings, urine, or nesting material that have been disturbed and become airborne in enclosed or dusty environments. This is how investigators believe the MV Hondius outbreak began — a birdwatching tour in Ushuaia, Argentina, where a Dutch couple likely inhaled particles from infected rodent droppings on the ground, with no awareness of exposure.
Direct contact with an infected rodent or its materials, or a rodent bite, can also transmit the virus. Touching contaminated surfaces and then touching the nose or mouth is another possible but less common route.
What are the symptoms of hantavirus pulmonary syndrome?
Hantavirus pulmonary syndrome progresses in distinct phases. The incubation period — the time between exposure and the onset of symptoms — ranges from one to six weeks, which is why WHO officials have warned that new cases may continue to emerge among MV Hondius passengers even after the ship docks and travellers return home.
The illness begins with a prodromal phase lasting three to five days, marked by fever, fatigue, muscle aches particularly in the thighs, hips, and back, headaches, dizziness, chills, and sometimes nausea and vomiting. This phase is easily confused with influenza. There is no rash. There is no sore throat. Most patients do not initially appear severely ill.
The cardiopulmonary phase follows rapidly and is where the disease becomes life-threatening. Fluid begins to accumulate in the lungs, causing progressive breathlessness. The heart’s pumping efficiency drops sharply. Patients can deteriorate from mild discomfort to critical respiratory failure within hours. Those who survive this phase — typically four to ten days of critical illness — generally recover fully, as the virus does not cause chronic infection.
Is there a treatment or vaccine for hantavirus?
There is no approved antiviral drug specifically for hantavirus pulmonary syndrome and no licensed vaccine available globally. Treatment is entirely supportive — intensive care, supplemental oxygen, and in severe cases, mechanical ventilation or extracorporeal membrane oxygenation to support breathing and cardiac function. Early transfer to an intensive care unit significantly improves survival chances, which is why the prompt medical evacuation of critically ill MV Hondius passengers to Johannesburg was clinically important.
Research into hantavirus vaccines and antiviral therapies is ongoing, but the virus’s relatively rare occurrence outside specific geographic clusters has historically limited research investment compared to more common infectious diseases.
Should the general public be worried?
Based on current evidence, no. The WHO has confirmed the overall public health risk from the MV Hondius outbreak remains low. The Andes strain’s human-to-human transmission requires prolonged, intimate contact — the kind that occurs between cabin-mates, spouses, or healthcare workers treating patients without adequate protection. Of 149 people who shared the same ship for weeks, only eight fell ill, a pattern consistent with the virus’s known transmission characteristics.
The six-week incubation window does mean health authorities will remain on alert, and contact tracing of over 80 passengers who shared a commercial flight with one of the victims is ongoing across multiple European countries. However, hantavirus is not a candidate for the kind of exponential community spread seen with respiratory viruses like influenza or SARS-CoV-2.
Disclaimer: This article is for informational purposes only and is based on publicly available information and WHO guidance. It does not constitute medical advice. Readers experiencing health concerns should consult a qualified medical professional.