For SeaEmploy readers, the key point is simple. A remote expedition route turned into a cross-border health response. By 8 May, WHO linked eight cases to the voyage, including three deaths, and confirmed Andes virus as the cause.
The ship left Ushuaia on 1 April. It then crossed the South Atlantic through mainland Antarctica, South Georgia, Nightingale Island, Tristan da Cunha, Saint Helena, and Ascension Island. Official headcounts differ slightly by update. WHO listed 147 people on board on 4 May, while ECDC and later updates from Oceanwide Expedition isused 149.
MV Hondius route changes after the outbreak alert
Illness appeared long before any lab named the virus. WHO says the first known patient developed fever, headache, and mild diarrhoea on 6 April. He died on board on 11 April. On 24 April, the ship reached Saint Helena, removed his body, and allowed 30 guests to leave the vessel.
The route still looked normal at that stage. The medical picture did not. The dead passenger’s wife left the ship on 24 April, deteriorated during her journey, and died in South Africa on 26 April. Another passenger fell seriously ill on 24 April, left via Ascension Island on 27 April, and later tested positive. A third passenger died on 2 May.
That is the moment the voyage changed direction in practice. Cabo Verde stood as the next scheduled port, but Oceanwide Expeditions said guests would not disembark there. Medical teams removed three people by specialised aircraft on 6 May. Later that day, the ship left Cape Verde and headed for Granadilla, Tenerife, with arrival expected early on 10 May.
Officials still have not published one confirmed exposure site. WHO and ECDC currently treat pre-boarding exposure in Argentina as the leading hypothesis. They also accept that limited secondary spread among very close contacts may have happened on board. That matters because the route itself likely did not create the outbreak, but the ship’s enclosed setting may have amplified close-contact risk after the virus entered the voyage.
Hantavirus strain confirmed on MV Hondius
The strain is now clear. WHO, ECDC, RIVM, and CDC Andes virus guidance all identify the outbreak virus as Andes virus, often shortened to ANDV. Public materials released so far do not name a narrower genotype below that level. So the most accurate current wording is this: MV Hondius has a confirmed Andes virus outbreak.
Andes virus stands apart from other hantaviruses. WHO and CDC both say it is the only hantavirus known to show limited human-to-human transmission. That does not mean easy spread in casual settings. It means close and prolonged contact can transmit infection, especially in shared cabins, enclosed rooms, or contact with body fluids from a symptomatic person.
The clinical risk is high. Andes virus can cause hantavirus cardiopulmonary syndrome, a severe illness that affects the lungs and heart. Early signs often look ordinary. Fever, headache, muscle pain, nausea, diarrhoea, cough, and chest discomfort can appear first. The dangerous phase can follow days later with respiratory distress, low blood pressure, shock, and rapid need for intensive care.
The fatality data explain the concern. WHO says hantavirus cardiopulmonary syndrome in the Americas can kill up to 50% of patients. RIVM says the Andes variant can kill 30% to 50%. CDC data for hantavirus pulmonary syndrome in the United States show a fatality rate of 38% once respiratory disease develops. The exact number varies by outbreak, but the pattern does not: this is a severe virus, not a mild travel infection.
Its contagiousness is limited, but it is real. A 2024 prospective study in Chile detected infectious Andes virus in saliva, nasal secretions, urine, and gum fluid during the acute phase. The same study linked virus outside blood to greater severity. That finding helps explain why close-contact spread can occur, even though the virus still does not behave like a freely airborne infection in the wider community.
Why the public risk stays low
Health agencies keep calling the public risk low for clear reasons. ECDC says person-to-person spread has only been documented after close and prolonged contact. It also notes that the natural rodent reservoir for Andes virus is not present in Europe, so this event is not expected to seed rodent-to-human transmission there. WHO repeated the low-risk assessment on 8 May.
Low public risk does not mean low individual risk. CDC says symptoms can appear 4 to 42 days after exposure. WHO advises active symptom monitoring for 45 days. UKHSA has already applied that logic by asking British passengers and crew from the ship to isolate for 45 days after their return. That long follow-up period reflects the virus’s incubation window, not panic.
