WHO monitors Hantavirus outbreak, says global risk remains low

• No travel or trade restrictions recommended at present

The World Health Organization (WHO) has reported a cluster of severe respiratory illness linked to Hantavirus infections among passengers and crew aboard a cruise ship operating in the South Atlantic, prompting an international public health response and global risk assessment. 

According to the WHO, a Dutch-flagged cruise ship carrying 147 people from 23 countries departed Ushuaia, Argentina, on 1 April 2026 and visited several remote destinations including mainland Antarctica, South Georgia, Nightingale Island, Tristan da Cunha, Saint Helena and Ascension Island before later mooring off Cabo Verde. 

On 2 May, the United Kingdom’s National International Health Regulations (IHR) Focal Point notified the WHO of a cluster of severe acute respiratory illness onboard, including two deaths and one critically ill passenger. 

Laboratory testing conducted in South Africa later confirmed Hantavirus infection in one critically ill patient. By 4 May, health authorities had identified seven cases, including two laboratory-confirmed infections and five suspected cases, while three deaths had been reported. Three suspected cases remained onboard under medical observation in Cabo Verde. 

The WHO said the source of exposure remains unclear, including whether contact with wildlife in visited locations may have contributed to transmission. Among the reported cases were passengers who developed severe respiratory distress, pneumonia and gastrointestinal symptoms. 

Despite the outbreak, the WHO currently assesses the global public health risk associated with the incident as low and has not recommended any travel or trade restrictions. 

Hantavirus infections are relatively uncommon globally but can result in severe illness and high mortality rates. The WHO said case fatality rates range from less than 1% to 15% in Asia and Europe and may reach up to 50% in the Americas. Worldwide, annual infections are estimated to range from 10,000 to more than 100,000 cases, with the largest burden recorded in Asia and Europe. 

In East Asia, particularly China and South Korea, Hantavirus-related haemorrhagic fever with renal syndrome continues to account for thousands of infections annually, although incidence rates have declined in recent decades. Europe reports several thousand cases each year, mainly in northern and central regions associated with the Puumala virus. In the Americas, Hantavirus cardiopulmonary syndrome remains much rarer but significantly more lethal, with South American countries such as Argentina, Brazil, Chile and Paraguay reporting small numbers of cases annually. 

The WHO said Hantavirus transmission to humans primarily occurs through contact with infected rodent urine, saliva or droppings, or contaminated surfaces. Infection risks increase during activities involving rodent exposure, including cleaning enclosed or poorly ventilated spaces, farming, forestry work and staying in rodent-infested environments. 

Human-to-human transmission remains uncommon and has only been documented for the Andes virus in the Americas, generally requiring prolonged close contact among household members or intimate partners. 

Symptoms of Hantavirus infection generally emerge between one and eight weeks after exposure and may initially resemble influenza or other viral illnesses, including fever, headaches, muscle pain and gastrointestinal symptoms such as nausea, vomiting and abdominal pain. In severe cases, the disease may rapidly progress to respiratory failure, fluid accumulation in the lungs and shock. 

The WHO noted that diagnosis can be difficult during the early stages because symptoms overlap with illnesses such as COVID-19, dengue, leptospirosis and viral pneumonia. Laboratory confirmation relies on serological testing and molecular methods including RT-PCR. 

There is currently no approved antiviral treatment or vaccine for Hantavirus infections. The WHO said treatment remains supportive and depends heavily on early clinical monitoring and access to intensive care facilities, particularly for patients with respiratory complications. 

Preventive measures focus primarily on reducing human exposure to rodents. Recommended measures include maintaining clean homes and workplaces, sealing building openings that allow rodent entry, storing food securely, avoiding dry sweeping of rodent droppings and strengthening hand hygiene practices. 

The WHO said infection prevention measures within healthcare settings remain critical, although available evidence suggests the risk of hospital-based transmission is very low when proper precautions are followed. Standard infection control measures, environmental cleaning and the safe handling of bodily fluids continue to be recommended for suspected and confirmed cases. 

The WHO said it continues to work with countries and international partners to strengthen surveillance, laboratory capacity, patient care, outbreak response, risk communication and public awareness relating to Hantavirus infections. The organisation also said it promotes a “One Health” approach linking human health, rodent reservoirs and environmental management to improve outbreak prevention and response strategies.