How hantavirus reached 16 countries in 42 days

Origin: Ushuaia, Argentina (1 April)

The chain began in Tierra del Fuego, the southernmost tip of South America. A Dutch couple, both in their seventies, had been birdwatching across Argentina since late 2025, moving through Neuquén and Misiones, both WHO-designated Andes virus endemic zones. Their final stop before boarding the MV Hondius was a landfill site near Ushuaia, where Malbrán Institute investigators are now trapping rodents to confirm the exposure source.

According to Argentine health authorities, the probable index cases were a married Dutch couple in their seventies who joined a birdwatching group near a waste disposal site outside Ushuaia shortly before the ship sailed on 1 April. Prior to boarding, the pair had travelled for several months across the southern cone — their itinerary threaded through areas in Neuquén province and Misiones, regions that WHO classifies as Andes virus hotspots. Researchers from Argentina's national reference laboratory have deployed field teams to capture and screen rodents at locations the couple visited.

The ship route: Ushuaia → Tristan da Cunha → Saint Helena → Cabo Verde → Tenerife

Andes virus is the only hantavirus known to pass between humans, but even that requires close, sustained contact — sharing meals, bedding, breathing the same confined air during the prodromal phase. Under normal circumstances, that means infection chains burn out within a single home or family group. A precedent existed: in the Patagonian town of Epuyén between late 2018 and early 2019, one infected individual set off a chain that eventually reached 34 residents, eleven of whom died.

The expedition vessel became, in effect, a maritime version of the Epuyén cluster. For weeks, 147 individuals from nearly two dozen nations ate at the same tables, walked the same hallways and gathered in the same common areas. Between the onset of symptoms on 6 April and the first death five days later, the pathogen had circulated silently among close contacts in the ship's communal spaces. Since the ship was nowhere near a hantavirus endemic zone, the medical team saw no reason to suspect a rodent-borne pathogen. No quarantine protocols were activated for 21 days.

The victims

Three people died. The 70-year-old Dutchman began showing symptoms six days into the voyage, a sudden fever accompanied by headache, stomach cramps and diarrhea. He died aboard the ship on 11 April. His widow left the vessel at Saint Helena on 24 April and took a flight toward Johannesburg, where her condition collapsed during transit. She was pronounced dead at the hospital shortly after landing. The airline subsequently contacted all travellers who had been on her onward connection. A third fatality, a German citizen, was also confirmed, though authorities have released limited information about this case.

Country-by-country status (WHO DON601, 13 May)

As of WHO DON601 (13 May 2026): 11 total cases, 8 confirmed, 1 inconclusive, 2 probable. Three deaths (2 confirmed Andes virus, 1 probable). New confirmed cases reported in France and Spain since 8 May. The inconclusive case is an American passenger retested after conflicting results from two laboratories. Sixteen Americans arrived at Nebraska (quarantine unit) and Atlanta (Emory University) on 11 May. Contact tracing spans the UK, Netherlands, Germany, Switzerland, France, Spain, South Africa, Singapore, Canada, Belgium, and multiple other countries.

The ship docked at Tenerife's Granadilla port on 10 May. Disembarkation completed 11 May. Charter flights repatriated passengers to six European countries and Canada. The ship departed Tenerife the same day. CDC has over 100 staff working full-time on the response, with Dr David Fitter as incident manager.

Current numbers

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