Health authorities across Europe, the United States, Asia and Africa have launched a major international epidemiological investigation and contact-tracing operation following an Andes hantavirus outbreak linked to cruise ship MV Hondius.
The operation has taken on particular urgency because the Andes hantavirus is the only known strain capable of transmitting from person to person under certain conditions — and because this is the first known large multinational cluster of the virus recorded on a cruise ship.
According to the latest reports from WHO, Reuters and European health authorities, five cases have been laboratory-confirmed, eight cases are suspected or confirmed in total, three people have died, and one patient remains in a critical condition in South Africa. Cases are under investigation in the Netherlands, Switzerland, Germany, Ireland and Singapore, though no wider transmission chain has been confirmed in any of those countries.
Authorities are focusing efforts on identifying and monitoring passengers who disembarked from the vessel before the outbreak was officially confirmed. At least 29 passengers from 12 countries left the MV Hondius before isolation and public health measures were fully activated and are now being monitored by their national health authorities.
The investigation has also been extended to passengers on commercial flights who travelled alongside individuals subsequently confirmed as cases. In some instances, airline crew members who had close contact with patients during those journeys are also being monitored.
Health services in Europe, the United States, Singapore and several African countries have activated specialist surveillance, isolation and medical assessment protocols for close contacts.
What is Andes hantavirus
Hantaviruses are normally transmitted from rodents to humans through the inhalation of infected particles from rodent urine, faeces or saliva.
The Andes hantavirus, found mainly in South America, is considered a special case: it is the only known strain with a documented, if limited, capacity for human-to-human transmission.
Experts say that transmission is not considered easy or widespread and appears to require prolonged, very close contact — typically in a family or healthcare setting. Nevertheless, the MV Hondius outbreak has heightened concern in the international scientific community because several aspects of the virus’s behaviour remain poorly understood.
Scientists speaking to major media outlets say significant questions remain, including the possibility of asymptomatic transmission, the degree of transmissibility before symptoms appear, and the duration of the infectious period. Research centres in Europe and South America are accelerating studies into experimental treatments and potential future hantavirus vaccines.
Surveillance has also been intensified because of the virus’s incubation period, which can reach six to eight weeks.
How the outbreak most likely began
Epidemiological analyses point to the first passengers having most likely been exposed to the virus before boarding the MV Hondius, during a wildlife and birdwatching trip in Argentina, Chile and Patagonia. Argentina has launched a rodent-testing and sampling programme in Ushuaia and Tierra del Fuego, where authorities consider the initial exposure increasingly likely to have occurred. The leading scenario is that limited transmission between passengers then followed during the voyage.
WHO, CDC and ECDC assessments
Despite the scale of the response, both the World Health Organisation and the European Centre for Disease Prevention and Control say the overall risk to the general public remains low to very low.
The US Centers for Disease Control and Prevention is monitoring returning travellers in Georgia, California, Arizona and Texas; no secondary cases or symptoms have been reported so far.
The ECDC has activated a specialist team and deployed a EU Health Task Force expert for on-site investigation, describing the situation as rapidly evolving. Spanish authorities are preparing a dedicated disembarkation and health management plan for the ship’s arrival in Tenerife to minimise any risk of exposure to the local population.
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