Hantavirus outbreak kills 3 on cruise ship. How deadly is this disease?

A suspected outbreak of hantavirus aboard a Netherlands-operated polar expedition cruise has alarmed health officials after three passengers died and several others fell ill during a multi-continental voyage.

The incident, unfolding on the MV Hondius, has prompted a coordinated response involving national governments and the World Health Organization (WHO), as officials attempt to understand how a rare rodent-borne virus surfaced in a maritime environment.

The ship, run by Oceanwide Expeditions, had embarked from Argentina roughly three weeks before the incident and carried approximately 150 passengers.

Its itinerary included stops in Antarctica and other remote locations before reaching waters near Cape Verde in the Atlantic Ocean.

What happened aboard the MV Hondius?

The outbreak came to light after multiple passengers developed symptoms consistent with a serious infectious disease during the voyage. Oceanwide Expeditions described the situation as a “serious medical” issue, as several individuals fell ill in quick succession.

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Three fatalities have been reported in connection with the outbreak. Dutch authorities confirmed that two of the deceased were citizens of the Netherlands, although further details about their conditions were not disclosed.

A third death involved a 70-year-old passenger whose case has provided key clinical insights into the progression of the illness.

South African health officials stated that the man became ill while the ship was travelling between Ushuaia in Argentina and the island of St Helena.

According to South Africa’s Department of Health spokesman Foster Mohale, the passenger “suddenly became ill” and experienced “fever, headache, abdominal pain, diarrhoea”, before dying on arrival at St Helena.

At least three additional passengers were reported to be unwell. One of them, identified in media reports as a British national, required intensive care treatment in South Africa. The WHO confirmed that hantavirus infection had been detected in at least one of the six affected individuals through laboratory testing.

Complicating the response, authorities in Cape Verde did not immediately allow passengers requiring medical care to disembark when the ship reached waters near Praia, the country’s capital.

This delay necessitated international coordination to arrange medical evacuations and further treatment.

“WHO is facilitating coordination between member states and the ship’s operators for medical evacuation of two symptomatic passengers, as well as full public health risk assessment and support to the remaining passengers on board,” the WHO said.

Meanwhile, ship tracking data indicated that the MV Hondius remained anchored off Praia as officials worked through logistical and health-related challenges.

The vessel itself is a specialised expedition ship measuring 107.6 metres in length, with accommodation for up to 170 passengers alongside crew, guides, and a medical professional.

With around 80 cabins onboard, most housing two passengers but some accommodating three or four individuals, the ship represents a relatively dense, self-contained environment.

What is hantavirus? Where does it come from?

Hantavirus is not a single pathogen but a group of viruses belonging to a broader family known as hantaviruses, which are carried by rodents. These viruses were first identified during the Korean War in the 1950s near the Hantan River, from which their name is derived.

Unlike many infectious diseases that rely on insect vectors such as mosquitoes or ticks, hantaviruses are transmitted directly from animal reservoirs — primarily rodents — to humans.

Various species of rodents, including deer mice, cotton rats, and bank voles, act as carriers. Notably, these animals do not exhibit symptoms of illness despite harbouring the virus, effectively becoming long-term carriers.

The viruses are distributed worldwide, with different strains associated with distinct geographic regions and clinical outcomes. In the Americas, hantavirus infections are most often linked to Hantavirus Pulmonary Syndrome (HPS), a severe respiratory condition.

In Europe, Asia, and Africa, infections more commonly lead to Hemorrhagic Fever with Renal Syndrome (HFRS), which primarily affects kidney function.

Although the disease is considered rare, it has been documented across multiple continents. In the United States alone, 864 cases were recorded between 1993 and 2022, with the highest numbers reported in states such as New Mexico, Colorado, and Arizona.

The recent attention surrounding hantavirus has also been shaped by high-profile cases, including the death of Betsy Arakawa, the wife of late actor Gene Hackman, who succumbed to the infection in New Mexico.

Hackman himself died about a week later from heart disease.

How is hantavirus transmitted to humans?

The primary pathway for hantavirus transmission involves exposure to materials contaminated by infected rodents.

When rodent urine, droppings, or saliva are disturbed, virus particles can become airborne and be inhaled by humans. This process, known as aerosolisation, is considered the most common route of infection.

Individuals may also contract the virus by touching contaminated surfaces and subsequently touching their eyes, nose, or mouth. Less frequently, infection can occur through the consumption of contaminated food or via bites from infected rodents.

Certain occupations and activities increase the likelihood of exposure. People working in forestry, agriculture, or trapping — where encounters with rodents are more common — are generally at higher risk.

Human-to-human transmission of hantavirus is exceedingly uncommon. The majority of known hantavirus strains do not spread between people.

However, one exception is the Andes virus, identified in South America, which has demonstrated limited person-to-person transmission under specific circumstances.

Given this context, investigators are examining whether the cruise ship outbreak involved a strain capable of such transmission or whether it resulted from environmental exposure, such as a localised rodent presence onboard.

What symptoms should people watch for?

One of the challenges in identifying hantavirus infections lies in the nature of its early symptoms, which closely resemble those of common viral illnesses. This similarity can delay diagnosis and treatment.

Symptoms typically begin to appear between one and eight weeks after exposure. In the initial phase, patients may experience fever, fatigue, muscle aches — particularly in large muscle groups such as the thighs, hips, and back — as well as headaches and chills.

Gastrointestinal symptoms, including abdominal pain, nausea, and diarrhoea, are also reported in a significant proportion of cases.

As the disease progresses, it can diverge into two major clinical forms depending on the strain involved.

In cases of Hantavirus Pulmonary Syndrome, patients develop respiratory complications. This stage is marked by coughing and increasing shortness of breath as fluid accumulates in the lungs, a condition known as pulmonary edema.

Without timely medical intervention, this can lead to respiratory failure and death. Mortality rates for HPS are estimated to be approximately 38 to 40 per cent.

In contrast, Hemorrhagic Fever with Renal Syndrome primarily affects the kidneys. Patients may experience intense back pain, low blood pressure, blurred vision, and, in severe cases, internal bleeding and acute kidney failure.

Fatality rates for HFRS vary widely depending on the strain, ranging from about 1 percent to as high as 15 per cent.

The cruise ship case has highlighted how quickly the disease can escalate. The 70-year-old passenger’s rapid deterioration — from initial symptoms to death — illustrates the potentially severe course of the infection.

Is there a treatment for hantavirus?

There is currently no specific cure, vaccine, or widely approved antiviral treatment for hantavirus infections. As a result, medical care is focused on supportive measures aimed at managing symptoms and preventing organ failure.

For patients with severe respiratory complications, treatment often involves admission to intensive care units, where they may receive oxygen therapy or mechanical ventilation to support breathing.

In cases involving kidney failure, dialysis may be required to assist in filtering waste from the blood.

An antiviral drug known as ribavirin has been used in some instances for treating Hemorrhagic Fever with Renal Syndrome, particularly in its early stages. However, its effectiveness in treating Hantavirus Pulmonary Syndrome remains unproven.

Medical experts point out that early detection and prompt hospitalisation significantly improve survival rates. Because the disease can progress rapidly once severe symptoms develop, delays in treatment can have serious consequences.

Why is a cruise ship an unusual but concerning setting for hantavirus?

Hantavirus is typically associated with rural or wilderness environments where human contact with rodents is more likely. Its appearance on a cruise ship — particularly a polar expedition vessel — has therefore raised serious questions about disease transmission in maritime settings.

Cruise ships are often described as semi-enclosed environments with high population density.

Passengers and crew share living spaces, dining areas, and ventilation systems, creating conditions that can facilitate the spread of infectious agents once introduced.

Another factor is the international nature of cruise travel. Ships frequently move between ports in different countries, bringing together individuals from diverse regions with varying levels of immunity and exposure history. In the case of the MV Hondius, the journey spanned multiple continents.

Also, expedition-style vessels, which often operate in remote and challenging environments, may face unique logistical constraints. Storage areas, supply chains, and maintenance conditions could present opportunities for rodent presence if not carefully managed.

The long incubation period of hantavirus also complicates matters. Because symptoms can take weeks to develop, infected individuals may not show signs of illness until well after the initial exposure, making it difficult to identify the source and prevent further transmission.

What steps are being taken to manage the outbreak?

International health authorities are actively involved in managing the situation. The WHO has taken a coordinating role, working with affected countries and the ship’s operators to facilitate medical evacuations, assess risks, and provide support to those still onboard.

Efforts are also underway to repatriate symptomatic passengers and the body of a deceased individual. Public health teams are conducting investigations to determine how the virus was introduced and whether additional cases may emerge.

At the same time, authorities are monitoring passengers and crew for symptoms, given the possibility of delayed onset due to the virus’s incubation period.

[This article is for informational purposes only. For medical advice or diagnosis, consult a professional.]

With inputs from agencies