WHO flags concern over suspected human hantavirus spread after cruise deaths

Hantavirus has long been seen as a rodent-borne threat. But emerging evidence that some strains may pass between humans is prompting fresh concern among health experts.

After the suspected hantavirus outbreak on a cruise ship off the coast of West Africa that led to the death of three people and four others critically ill, the World Health Organisation said on Tuesday that it suspects some rare human-to-human transmission to have happened among passengers. Hantavirus is primarily a rodent-borne virus.

The agency has underlined that the risk to the wider public remains low, and has urged calm while investigations are underway.

The outbreak has so far claimed three lives: a Dutch couple and a German national. A British passenger, who tested positive for the virus, is currently being treated in intensive care in a Johannesburg hospital. Three additional suspected cases remain on board, including one individual with only mild symptoms.

At the centre of the outbreak is the Hondius, a high-end vessel now effectively stranded off the coast of Cape Verde. Authorities have not permitted passengers to disembark, leaving roughly 150 people confined to the ship as health teams assess the situation.

What was meant to be a once-in-a-lifetime Antarctic expedition has, in a matter of weeks, turned into a tightly managed public health response unfolding at sea.

TRACING THE ORIGIN: INFECTION LIKELY BEFORE BOARDING

Initial findings suggest the virus was not contracted on the ship, but rather introduced by passengers who boarded earlier in Argentina. The Dutch couple, believed to be among the first cases, may have been exposed during outdoor activities such as birdwatching—settings where contact with rodent-contaminated environments is possible.

From there, the virus appears to have spread in a limited way between close contacts, particularly among those sharing cabins.

Maria Van Kerkhove of the WHO noted that transmission may have occurred between “really close contacts”—a pattern consistent with what is known about certain strains of hantavirus.

A RARE MODE OF SPREAD

Hantavirus infections are primarily zoonotic, meaning they spread from animals—usually rodents—to humans. Infection typically occurs when people inhale virus particles from rodent urine, droppings, or saliva.

Human-to-human transmission is considered extremely uncommon, but not unheard of. The WHO believes the strain involved in this outbreak could be the Andes virus, a variant found in parts of South America that has, in past outbreaks, shown the ability to spread between people in very close contact.

Even in such cases, transmission is usually limited to intimate settings, such as between partners or caregivers. There is no evidence of the virus spreading easily through casual contact or in wider community settings.

SYMPTOMS THAT CAN BE EASY TO MISS

One of the challenges with hantavirus is that it often begins like a common flu, with fever, fatigue, and muscle aches. This early phase can last several days, during which the illness may go unrecognised.

In more severe cases, the infection can progress rapidly to hantavirus pulmonary syndrome, a life-threatening condition where fluid builds up in the lungs, causing breathing difficulties. The fatality rate for this form of the disease can be high, making early detection critical, yet difficult.

Health protocols on the ship have been intensified. Symptomatic individuals and those caring for them are using full personal protective equipment, and additional medical supplies have been delivered.

Disinfection efforts are ongoing, and importantly, the WHO has been informed that no rodents have been detected on board, reinforcing the likelihood that the virus was introduced from outside rather than originating on the vessel itself.

Plans are underway to evacuate the remaining ill passengers to the Netherlands for further care. The ship is expected to continue towards the Canary Islands, though authorities there have yet to confirm whether it will be allowed to dock. Spain’s health ministry has said a decision will depend on evolving epidemiological data.

A VOYAGE THROUGH REMOTE REGIONS

The cruise, which began in southern Argentina in March, was marketed as an Antarctic nature expedition, with ticket prices running into thousands of euros. It included stops at some of the most remote locations on Earth, including the Antarctic Peninsula and isolated islands in the South Atlantic.

The remoteness that made the journey appealing has also complicated the response, turning the ship into a contained but high-stakes environment for managing an infectious disease.

PUBLIC RISK IS LOW

Despite the seriousness of the cases on board, the WHO has reiterated that there is little risk to the general public. This is because:

• Hantavirus is not easily transmitted between humans
• When transmission does occur, it is usually limited to very close, prolonged contact
• There is no evidence of widespread or community-level spread in this incident

WHO has said that this outbreak, while tragic, does not signal a broader threat.

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