A returning passenger from the hantavirus-stricken MV Hondius cruise ship tested positive in Switzerland on Wednesday, the first off-ship case from an outbreak that has killed three people on board.

He is one of roughly 23 passengers who scattered home from Saint Helena on April 23, before contact tracing began.

The man initially tested negative on returning home, but the Andes virus can incubate for as long as eight weeks, the World Health Organization said.

The Hondius set sail from Ushuaia, Argentina, on April 1, and within 10 days the first passenger was dead. Argentine investigators believe he and his wife, who later died in a Johannesburg hospital, contracted the virus on a pre-cruise birdwatching tour at a local landfill. A German woman became the third fatality on May 2.

Prediction Markets See A Contained Cluster

Polymarket thinks there is a 10% chance we see a Hantavirus pandemic in 2026. The market has over $600,000 in volume.

The broader “new pandemic in 2026” market is at 12%.

Prominent forecaster Peter Wildeford put the pandemic risk at under 1% in a post on X this week, citing Andes’ three-decade record of self-extinguishing outbreaks.

The largest documented Andes cluster, in Epuyén, Argentina in 2018-19, produced 34 cases and 11 deaths before contact tracing contained it.

Why Andes Doesn’t Spread Like COVID

Unlike COVID, Andes does not spread through casual airborne exposure. It is the only hantavirus capable of person-to-person transmission, but the virus moves through large saliva droplets and requires close, prolonged contact such as shared cabins or caregiving.

On the Hondius, the first victim’s wife and the ship’s doctor were both infected through extended close contact.

The virus floods the victim’s lungs with fluid, with a case fatality rate as high as 50% and no licensed antiviral or vaccine available.

Cruise Stocks In Focus

Cruise stocks Carnival Corp (NYSE:CCL), Royal Caribbean Cruises (NYSE:RCL) and Norwegian Cruise Line Holdings (NYSE:NCLH) have not been affected yet, perhaps because the MV Hondius is a 196-passenger polar expedition ship with no operational link to the major lines.

That insulation could fade if more off-ship cases emerge among the disembarkees scattered home from Saint Helena.

The Hondius is expected to dock in Tenerife around May 11. Until then, WHO contact tracing continues across more than ten countries.

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