Just like lassa fever, the virus is primarily carried by rodents such as mice and rats, which serve as the main reservoir and source of human infection.
The World Health Organisation (WHO) has confirmed an outbreak of hantavirus infection aboard a cruise ship carrying 147 passengers and crew, following a cluster of severe respiratory illnesses reported on Tuesday.
The outbreak has so far recorded seven cases, including two laboratory-confirmed infections, five suspected cases, and three deaths.
One patient remains critically ill in intensive care, while three others have mild symptoms and are being monitored on board the vessel, currently moored off the coast of Cabo Verde.
Health authorities in Cabo Verde, the Netherlands, Spain, South Africa and the United Kingdom are coordinating response measures with WHO support, including isolation of symptomatic passengers, enhanced infection control, and ongoing laboratory investigations.
What is hantavirus?
Hantavirus Pulmonary Syndrome is a rare but severe zoonotic disease caused by viruses in the Orthohantavirus genus.
Just like lassa fever, the virus is primarily carried by rodents such as mice and rats, which serve as the main reservoir and source of human infection.
Humans are usually infected through inhalation of aerosolised particles from infected rodent urine, droppings, or saliva, or through direct contact with contaminated surfaces. In rare cases, infection may occur through rodent bites.
Human-to-human transmission is generally uncommon, although limited transmission has been reported in previous outbreaks involving specific strains such as Andes virus.
The illness typically begins with non-specific flu-like symptoms, including fever, fatigue, muscle aches, headache, and sometimes gastrointestinal symptoms such as nausea, vomiting, diarrhoea, and abdominal pain.
It can then progress rapidly to severe respiratory distress as fluid accumulates in the lungs, leading to acute respiratory failure and shock.
Symptoms usually appear between two and four weeks after exposure, although the incubation period may range from one to eight weeks.
According to the WHO, there is currently no specific antiviral treatment or licensed vaccine for hantavirus infection.
Management, the health body added, is mainly supportive and often requires intensive care, including oxygen therapy, mechanical ventilation, and careful fluid management.
Early recognition and prompt treatment, the WHO said, significantly improve survival.
According to WHO, symptoms among affected passengers began between 6 and 28 April 2026, initially presenting as fever and gastrointestinal illness before rapidly progressing to pneumonia, acute respiratory distress syndrome and shock.
The vessel, a Dutch-flagged cruise ship, departed Ushuaia, Argentina, on 1 April 2026, and travelled across remote South Atlantic and sub-Antarctic regions, including Antarctica, South Georgia, Tristan da Cunha, Saint Helena and Ascension Island.
Investigators are still assessing possible exposure points, including contact with wildlife or contaminated environments before embarkation and during the voyage.
Three deaths have been reported in connection with the outbreak.
Case 1, an adult male, developed symptoms on board on 6 April and died on 11 April without laboratory testing.
Case 2, a close contact, deteriorated during a medical evacuation flight to South Africa and later tested positive for hantavirus before dying on 26 April.
Case 3, an adult male, was medically evacuated from Ascension Island and remains in intensive care in South Africa following severe respiratory illness.
Case 4, an adult female, died on 2 May after developing fever and general malaise on 28 April.
Three additional suspected cases remain under observation on board the vessel.
WHO said measures already implemented include isolation of symptomatic passengers, symptom monitoring for passengers and crew, enhanced sanitation procedures on board, and medical evacuation of critically ill patients.
Passenger and crew lists have been shared with national authorities to support contact tracing, including for passengers on a medical evacuation flight linked to a confirmed case.
Laboratory confirmation has been conducted at South Africa’s National Institute for Communicable Diseases (NICD), while additional samples are being analysed at the Institut Pasteur de Dakar in Senegal. Sequencing and metagenomic studies are also ongoing.
WHO said it has assessed the global risk from the outbreak as low but said investigations are ongoing.
The organisation noted that hantavirus infections remain rare globally but can be severe, with case fatality rates ranging from less than one per cent to as high as 50 per cent in parts of the Americas.
It added that environmental factors, particularly rodent population surges linked to ecological conditions, can influence transmission patterns.
WHO said it will continue to monitor the situation and update its risk assessment as more information becomes available.
