Hantaviruses

Epidemiology

Hantaviruses belong to the family Hantaviridae and are found on every continent. More than 20 viral species have been identified, all of which are zoonotic – that is, transmitted by animals. Each viral taxon is generally associated with a single natural host species, mainly including wild rodents (rats, voles, field mice) and, more rarely, insectivorous rodents (moles, shrews), bats, as well as fish and reptiles.

Current situation

On 3 May 2026, the World Health Organisation (WHO) issued an alert regarding a possible outbreak of hantavirus infection on board the Dutch cruise ship MV Hondius travelling from Ushuaia, Argentina, to Cape Verde.

As of 5 May 2026, two cases of hantavirus infection had been laboratory-confirmed and five further cases were suspected among the 147 passengers and crew members. Of the seven people who fell ill, three have died and one was in intensive care in South Africa. The latter, a British tourist who tested positive for a hantavirus, had been transferred and hospitalised in Johannesburg.

On 6 May 2026, viral sequencing carried out by the South African health authorities identified a strain of the Andes hantavirus. ¹ This is the only strain, out of the 38 known, capable of being transmitted from person to person, although this mode of transmission remains marginal compared to exposure to infected rodents. Further epidemiological investigations are ongoing. These should provide a better understanding of the key circumstances of this outbreak and enable a precise assessment of the risk of human-to-human transmission.

Currently grounded in Cape Verde, the ship has not been authorised to dock, but medical care is being provided to passengers and crew. The Spanish government has however authorised its reception in the Canary Islands in the near future, in order to continue the examination, care and transfer of passengers. The risk of the virus spreading beyond the ship is still considered ‘low’ by the WHO. ²

Historical background

The first clinical description of a hantavirus disease dates back to the Korean War (1950–1953), during which more than 3,000 soldiers developed haemorrhagic fever with hepatorenal syndrome. The virus responsible was identified in 1976 by Korean researchers. It is named after the Hantaan River, which lies on the border between the two Koreas.

Global circulation

Hantavirus infections are relatively rare worldwide. However, their case fatality rate varies between the regions affected (and the viral species involved) and can reach up to 50% of cases. Globally, it is estimated that between 10,000 and 100,000 cases occur each year, mainly affecting Asia and Europe. ³

In 2025, eight countries in the Americas reported confirmed cases of hantavirus pulmonary syndrome, totalling 229 cases and 59 deaths. The countries concerned are Argentina, Brazil, Bolivia, Chile, Panama, Paraguay, the United States of America and Uruguay. ⁴

In France

Between January and March 2026, the National Reference Centre (CNR) for Hantaviruses, part of the Pasteur Institute in Paris, recorded 19 confirmed cases of recent hantavirus infection. The number of cases detected is in line with the French monthly average. In French Guiana, since 2008, only eleven cases of Maripa hantavirus pulmonary syndrome have been detected, six of which were fatal. ⁵

Clinical characteristics

Transmission

The virus is transmitted to humans mainly through indirect contact via the inhalation of aerosols contaminated by the excreta (urine, faeces) of asymptomatic infected rodents (referred to as ‘reservoir’ animals) and, more rarely, through direct contact or bites. Cases generally occur in rural areas, where forests, fields and farms provide a suitable habitat for rodents.

Human-to-human transmission of a hantavirus is rare. It was first confirmed during a nosocomial outbreak of hantavirus pulmonary syndrome in 1996 in southern Argentina and appears to involve only the Andes hantavirus, which is endemic in that country.

Symptoms & Diagnosis

When they affect humans, hantaviruses can cause infections of varying severity, some of which are life-threatening.

The incubation period lasts an average of two weeks. The initial clinical symptoms are generally those of influenza: fever, headache, and muscle pain. Two types of syndrome may then be observed:

• either haemorrhagic fever with renal syndrome, with a case-fatality rate of 0.4 to 10%;
• or severe acute cardiopulmonary syndrome with respiratory and cardiac failure, with a case-fatality rate of around 30 to 60%.

Both syndromes can be caused by the same viral species. However, renal and hepatic syndrome is more commonly found in European and Asian hantaviruses (commonly referred to as ‘Old World hantaviruses’), whilst pulmonary syndrome is more commonly observed in American hantaviruses (or ‘New World hantaviruses’).

Treatment & Prevention

No specific treatment or vaccine is approved, fully effective or widely available internationally against hantavirus infection. Vaccines against Hantaan and Seoul hantaviruses are produced and used only in China and South Korea, but with moderate efficacy. ⁶

Prevention of infection essentially involves limiting contact with rodents and their excretions. This requires avoiding, in high–risk areas: handling wood, cleaning premises that have been unoccupied for a long time, and any activity that stirs up dust or soil, such as renovating old, dusty premises, backfilling, etc.

The work of ANRS MIE

The ANRS MIE supports, facilitates and coordinates research into emerging infectious diseases. Hantaviruses are among these.

The ANRS MIE has supported a research project on hantaviruses as part of the 2025 edition of its call for proposals, ‘Émergence PRFI 2025’. This ongoing project, entitled “TRANSVI”, aims to characterise the transmission chains of hantaviruses between wildlife and humans on the Yucatan Peninsula (Mexico).

Also in 2025, one of the three “Emerging Viruses” thesis prizes awarded, as every year, by ANRS MIE and the French Society of Virology (SFV), was awarded to Dr Quentin Durieux Trouilleton (University of Grenoble / IBS) for his thesis “Structural and functional analysis of Bunyavirus replication and transcription”, focusing in particular on two hantaviruses. His work led him to observe, for the first time, a hantavirus polymerase – a molecule essential for the replication and therefore the spread of this virus.

A key player in numerous international partnerships and consortia, ANRS MIE is also part of the WHO’s Collaborative Open Research Consortium (CORC) network. In this context, links have been established with the UK Health Security Agency (UKHSA), which leads the Bunyavirales CORC, whose mission is to coordinate research as part of preparedness for hantavirus epidemics.

Finally, hantaviruses are discussed within several of its scientific working groups known as coordinated actions (ACs): the AC “Viral Haemorrhagic Fevers”, the AC “Host-Virus Interactions” and the AC “Human-to-Human Transmission of Respiratory Viruses”.

References

1. Hantavirus-hit cruise ship to sail to Spain; rare Andes strain confirmed, 6 May 2026 – Reuters. https://www.reuters.com/business/healthcare-pharmaceuticals/two-cases-hantavirus-which-spreads-human-to-human-linked-ship-south-africa-says-2026-05-06/
2. Hantavirus cluster linked to cruise ship travel, Multi-country, 4 May 2026 – World Health Organization. https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON599
3. Hantavirus, Fact Sheets – World Heath Organization. https://www.who.int/news-room/fact-sheets/detail/hantavirus (consulted on 5 May 2026)
4. Epidemiological Alert Hantavirus Pulmonary Syndrome in the Americas Region, 19 December 2025 – Pan American Health Organization (WHO). https://www.paho.org/sites/default/files/2025-12/2025-12-19-epidemiological-alert-hantavirus-engfinal_0.pdf
5. Hantavirus, Données – Santé publique France. https://www.santepubliquefrance.fr/hantavirus/donnees (consulted on 5 May 2026)
6. La maladie, Recommandations CNR Hantavirus – Institut Pasteur. https://www.pasteur.fr/fr/sante-publique/CNR/les-cnr/hantavirus/la-maladie-recommandations (consulted on 5 May 2026)