Hantavirus Outbreak Response unit

The Outbreak Response programme

On 7 May 2026, the ANRS MIE decided to activate a Level 1 Outbreak Response Unit. This involves establishing enhanced scientific monitoring and defining research priorities with a focus on prevention (crisis preparedness) in collaboration with scientific communities, expert groups and associations, as well as producing information for public decision-makers.

The ANRS MIE organised an initial research meeting on 11 May, attended by researchers, doctors and representatives of the health authorities (Directorate General for Health, Santé publique France, etc.).

Know more on the Outbreak Response programme

The hantavirus outbreak on board a cruise ship

On 2 May 2026, the World Health Organisation (WHO) issued a warning about a possible hantavirus outbreak on board the Dutch cruise ship MV Hondius, which was travelling from Ushuaia in Argentina to Cape Verde.

The ship, which had departed from Ushuaia on 1 April, was carrying 147 passengers and crew members. During its voyage, a number of passengers disembarked, notably during a stopover on Saint Helena. The ship was not permitted to dock upon its arrival in Cape Verde on 3 May, and medical care was provided for the passengers and crew. The ship was eventually received at the port of Tenerife, in the Canary Islands, on 10 May to continue the examination, care and transfer of passengers.

As of 8 May 2026, the risk of spread beyond the ship was considered ‘low’ by the WHO.^1,3

A public health event involving human-to-human transmission

As of 11 May 2026, a total of ten cases of Andes hantavirus infection had been identified in connection with the outbreak on board the MV Hondius, comprising eight confirmed cases and two probable cases. Three deaths were reported, reflecting a high case fatality rate estimated at between 30 and 38%.

The cases and management involve several countries, notably South Africa, the Netherlands, Switzerland, Spain, Denmark and the British Overseas Territory of Saint Helena, Ascension and Tristan da Cunha, highlighting the international dimension of this health event. Patients have a high median age, ranging from 65 to 69 years, with a predominance of males.

As a precautionary measure, all passengers and crew members of the MV Hondius are currently considered ‘high-risk contacts’. Prior to the identification of the outbreak, 30 passengers of more than twelve nationalities had disembarked on Saint Helena on 24 April, leading to an international spread of contacts. Added to this are secondary contacts identified following the evacuation of one of the cases by air.

In total, 161 contacts have been identified and are being monitored for 42 days following their last exposure. Given the potentially long incubation period, the emergence of new cases in the coming weeks cannot be ruled out.

Epidemiological investigations are underway to monitor the situation of passengers and crew members still on board, as well as those who may have been transferred off the ship. 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.

Eight French citizens have been identified among the close contacts. On 11 May 2026, the Ministry of Health confirmed that one of these individuals had tested positive and was experiencing mild symptoms. The Government has also issued a decree to strengthen isolation measures for close contacts.

Identification of the virus involved

On 6 May 2026, molecular biology analysis of the strain involved in the MV Hondius outbreak, carried out by the South African health authorities, identified a strain of the Andes hantavirus. This is the only strain, among the 38 known strains, capable of being transmitted from person to person, although this mode of transmission remains marginal compared to exposure to infected rodents. ²

The full sequence was published on 8 May, confirming its affiliation with the South American Andes virus (closely related to strains previously described in Argentina and Chile). At this stage, no specific mutations associated with increased transmissibility or virulence have been reported. The available data do not suggest the emergence of a distinct new variant, but further phylogenetic and functional analyses are underway.

Source of transmission

The current leading hypothesis is that initial infection occurred prior to embarkation in South America, followed by human-to-human transmission on board the vessel.

The first cases had notably visited high-risk sites in Argentina, Chile and Uruguay for birdwatching, with possible exposure to infected rodents—a scenario consistent with the known ecology of the Andes virus in Patagonia.

The occurrence of cases among people who shared enclosed spaces, cabins or had prolonged contact reinforces the hypothesis of human–to–human transmission, a rare but documented phenomenon for the Andes virus, the only hantavirus known to possess this ability.

Know more on Hantaviruses

Bibliography

1. 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
2. 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/
3.  Hantavirus cluster linked to cruise ship travel, Multi-country, 8 May 2026 – WHO. https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON600 (consulted on 11 May 2026)