OUTBREAK: Hantavirus

Background

Hantaviruses are a group of viruses that can cause mild or severe disease disease in humans. Hantaviruses circulating in the Americas can cause a severe respiratory illness called hantavirus cardiopulmonary syndrome (HCPS), while hantaviruses in Europe and Asia are known to cause haemorrhagic fever with renal syndrome (HFRS). Case fatality varies for different viruses, from <1-15% in Europe and Asia to up to 50% in the Americas. Globally, cases of hantavirus are uncommon, numbering in the tens or hundreds of thousands anually, mostly in Asia and Europe, with fewer but more severe cases in the Americas.

Hantaviruses are typically transmitted to humans from rodents through urine, faeces or saliva, however limited human-to-human transmission of Orthohantavirus Andesense (Andes virus), one species of Hantavirus, has been reported among close contacts. Symptoms can take one to eight weeks to appear after exposure.

Two species of Hantavirus, Orthohantavirus sinnombreense (Sinnnombre virus) and Orthohantavirus hantanense (Hantaan virus), are recognised as high risk for their potential to cause a Public Health Emergency of International Concern (PHEIC) by the World Health Organization. Orthohantavirus andesense is responsible for most cases in South America.

There are no licensed antiviral treatments or widely available vaccines for hantavirus infection. Ribavirin has shown some efficacy against hantavirus haemorrhagic fever with renal syndrome but not hantavirus cardiopulmonary syndrome. Timely supportive care for symptoms is critical, including the use of antipyretics, analgesics, respiratory support, vasopressors and dialysis, as symptoms indicate. Close monitoring and early transfer to intensive care units is required due to the rapid progression of HCPS.

There are three vaccines for hantaviruses licensed and used in Asia: ‘Hantavax’, ‘Puumala’ inactivated’ and ‘Seoul’ inactivated’, for Orthohantavirus hantanense, puumalaense and seoulense respectively. A further Orthohantavirus hantanense and Puumalaense combined vaccine candidate, ‘HTNV/PUUV DNA vaccine’, is in Phase 2 clinical trials. Preclinical research towards a vaccine for Orthohantavirus Andesense is being conducted by National Institute of Allergy and Infectious Diseases in the United States of America. The current state of medical countermeasure development for hantaviruses is monitored by WHO R&D Blueprint for Epidemics.

Hantavirus cluster on a cruise ship in the Atlantic

On 2 May 2026, a cluster of cases of respiratory illness among passengers on a Dutch cruise ship carrying 147 people in the Atlantic Ocean was reported to the World Health Organization (WHO). On 6th May, Andes hantavirus was confirmed as the cause of the outbreak. As of 26 May 2026, eleven laboratory confirmed cases of hantavirus have been confirmed, alongside two further probable cases. There have been three deaths, indicating a case fatality ratio around 23%. Three new cases have been identified since the 13 May. All confirmed and suspected cases to date had been passengers or crew on the MV Hondius. Symptoms among confirmed and suspected cases have included fever, gastrointestinal symptoms, rapid progression to pneumonia, acute respiratory distress syndrome and shock. As of 28 May 2026, WHO assesses the risk to the global population as low.

The ship departed Argentina on 1 April and has made multiple stops across the South Atlantic, including in mainland Antarctica, South Georgia, Nightingale Island, Tristan da Cunha, Saint Helena and Ascension Island, and was located off the coast of Cabo Verde before being directed to the Canary Islands for evacuation. The source of the outbreak is not known, but the working hypothesis is that the first case may have been exposed during travel to Argentina before boarding the cruise. The body of the first deceased passenger was released in St Helena (a British Overseas Territory), two further cases received treatment in South Africa, and a confirmed case presented in Switzerland after having left the cruise. Three suspected cases were medically evacuated from Cabo Verde before the ship continued to Tenerife for safe disembarkation and quarantine of all on board on 10th and 11th May, bar a skeleton crew who disembarked in the Netherlands on 18th and 23rd May. WHO recommends 42-day isolation of high-risk contacts.

Authorities from Cabo Verde, the Netherlands, Spain, South Africa and the United Kingdom are involved in the management of the public health response, including determining the source, laboratory testing and characterisation, contact tracing, clinical management and infection prevention measures.

Further information on the current situation, WHO risk assessment and advice is available through WHO Disease Outbreak News: Hantavirus outbreak linked to cruise ship travel, Multi-locations.

More information about the Hantavirus outbreak is provided here.

Key public health and research updates

May 2026: 

• WHO published Hantavirus outbreak linked to cruise ship travel, Multi-locations
• WHO published WHO Disease Outbreak News: Hantavirus cluster linked to cruise ship travel, Multi-country
• WHO updated Hantavirus Fact Sheet (WHO)
• WHO updated Hantavirus Outbreak Toolbox

July 2024: 

• WHO published ‘Pathogens prioritization: a scientific framework for epidemic and pandemic preparedness’ listing Orthohantavirus sinnombreense (formerly Sinnnombre virus) and Orthohantavirus hantanense (formely Hantaan virus) as being high PHEIC (Public Health Emergency of International Concern) risks.

Outbreak-specific research priorities

No outbreak specific research priorities outside of characterising the current outbreak in terms of it’s origins and transmission routes have been identified. The Bunyavirales Collaborative Open Research Consortium (CORC), which is tasked with identifying research priorities for the sub-families Hantaviridae, Nairoviridae, Peribunyaviridae, and Phenuiviridae, recently developed a research and development roadmap for Oropouche Virus, but has not yet published one for hantaviruses. 

Pandemic PACT data

See below our data visualisations for Hantavirus research grant funding.