Ushuaia landfill: the index-case theory seriously called into question

When the international press identified, on 11 May 2026, Leo Schilperoord, a 70-year-old Dutch ornithologist, as the index case of the MV Hondius hantavirus outbreak, attention immediately turned to an unlikely place: a municipal landfill 6 km from Ushuaia. Relayed by the New York Post then echoed by dozens of international outlets, this theory has, in just a few days, become seriously questioned by the WHO, the local Argentine authorities and several specialists. Update of 14 May 2026.

27 March 2026: the visit #

According to information gathered by the international press, Leo and his wife Mirjam Schilperoord spent several months travelling across South America between late 2025 and spring 2026. Argentina, Chile, Uruguay, then back to Argentina in late March for what was meant to be a final stop before joining the MV Hondius at Ushuaia, in Tierra del Fuego, on 1 April.

On 27 March 2026, five days before boarding, the couple visited the Ushuaia municipal landfill, located about 6 km north-west of the city. This is one of the last documented birding observations of the couple before boarding.

Why this landfill draws birders from around the world #

At first glance, the choice of destination seems odd. But for ornithologists specialised in South American raptors, the site is a pilgrimage destination. It hosts an exceptional concentration of white-throated caracaras (Phalcoboenus albogularis), also known as Darwin's caracara — a falconiform raptor endemic to southern Patagonia, southern Chile, and Tierra del Fuego.

Why would a raptor congregate at a landfill? The white-throated caracara is an opportunistic scavenger. Like other caracaras, it feeds on animal remains, organic waste, and occasionally small live rodents. Patagonian landfills act as artificial habitats with concentrated, accessible food, making them particularly productive observation sites for amateur and professional birders.

The contamination hypothesis #

Argentine investigators and the international press converge on the following hypothesis: the Schilperoords inhaled aerosols contaminated by the droppings of rodents present at the site.

The proposed mechanism is classic for hantavirus diseases:

1. Reservoir rodents live in the landfill, drawn by organic waste
2. They shed the virus in their urine, faeces and saliva without showing symptoms
3. When these droppings dry and mix with dust, viral particles become airborne
4. Inhalation of these aerosols, especially during prolonged exploration of a densely populated site, can be enough to cause infection

The Andes virus incubation period — between 7 and 42 days — matches the observed timeline perfectly: exposure on 27 March, first symptoms on 6 April, death on 11 April.

Why this hypothesis is seriously called into question #

Within a few days, the « Ushuaia landfill » theory has lost ground. Several converging arguments — local-authority statements, ornithologists' testimony, zoological data, the temporal argument and finally the WHO's position — make it at best secondary, at worst incorrect.

1. The local authorities: a « smear campaign » #

As early as 8 May 2026, Juan Facundo Petrina, Director General of Epidemiology and Environmental Health for the province of Tierra del Fuego, publicly rejected the idea that Ushuaia is the origin of the outbreak. To Euronews on 12 May, he went further: « I believe we are facing a smear campaign against this destination. » His arguments:

• The last human hantavirus case documented in the province dates back to 1996 — nearly thirty years ago.
• The provincial authorities learned of the suspicions through media reports rather than via international coordination channels — which raises questions about the origin of the leak.
• No veterinary investigation of local rodents has, to date, detected the presence of Andes virus or a related strain.

2. The ornithological guide's testimony #

Esteban Daniels, a local ornithological guide who has been bringing groups to the Ushuaia landfill for 25 years, told Franceinfo that he has never seen rodents at the site over the entire period. He also indicates that the Schilperoord couple was not part of any of his guided groups — they came alone, at a date he cannot confirm having seen them on site. This testimony, while not conclusive (the couple could have come outside of guided tours), weakens the image of a site obviously infested with reservoir rodents.

3. The zoological argument #

Ushuaia lies about 1,500 km south of the documented range of the subspecies of Oligoryzomys longicaudatus (the long-tailed pygmy rice rat or colilargo) known to carry Andes virus. The reservoir species' typical range covers Argentine and Chilean Patagonia further north, the Lake District and the Río Negro, Neuquén and Chubut provinces. Its presence in Tierra del Fuego is not impossible — climate change is shifting the distribution of many species — but it remains undocumented to date.

4. The temporal argument — the most decisive #

Andes virus's minimum incubation period is estimated at 9 days (median 21 days, maximum 42 days). Yet between the alleged exposure (27 March 2026 at the landfill) and Leo Schilperoord's first symptoms (6 April 2026 aboard the MV Hondius), only 7 days elapsed. Strictly speaking, this duration is shorter than the minimum incubation observed for the virus. Either the exposure took place earlier (during another stop on the couple's South American trip), or the landfill hypothesis is incorrect.

5. WHO position #

On 13 May 2026, Dr Boris Pavlin, team lead for Field and Humanitarian Epidemiology at the WHO, told ABC News that investigators have begun ruling out some of the circulating theories. According to him, the virus likely does not come from the ship's Argentine departure point. Early evidence rather points to exposure in the Andes Cordillera spanning northern Argentina and Chile — that is, several hundred kilometres further north than Ushuaia. The WHO continues its coordinated investigation with the Argentine authorities, the COREB mission and the Pasteur Hantavirus CNR.

Where does the landfill theory come from? #

Tracing back the chain of dissemination is instructive:

1. The first mention of the Ushuaia landfill as a probable exposure site appeared in the New York Post on 11 May 2026, citing « sources close to the investigation » without naming them.
2. The Spanish-language press (El País, Infobae) then relayed the information, before the international media (Newsweek, NBC News, Euronews) picked it up — most often crediting the New York Post.
3. Yet no health authority (WHO, ECDC, CDC, Argentine national authorities) has, to date, officially confirmed that the landfill is the contamination site.
4. The Tierra del Fuego provincial authorities deny it outright.

It thus appears that the « Ushuaia landfill » theory rests for now on a single unsourced press report, amplified by international media echo, without official corroboration.

A science still incomplete #

This divergence opens several leads that the international epidemiological investigation must clarify:

• Was exposure elsewhere in South America during the previous months — at another stop on the couple's journey in northern Argentina, Chile or Uruguay — the actual contamination point?
• Could another rodent species present in Tierra del Fuego carry a related, as-yet-undescribed hantavirus strain?
• Could a recent range extension of the long-tailed pygmy rice rat, linked to climate change, explain an unusual presence so far south?

On 5 May 2026, the Swiss National Reference Centre for Emerging Viral Infections published the whole-genome sequencing of the virus from the Swiss case (Case 7). The virus belongs to the Andes strain, genetically very close to the Argentine Epuyén 2018-2019 outbreak, with no unusual mutation or documented recombination. This result is fully compatible with exposure in the northern Andes Cordillera (the geographical area pointed to by the WHO), and does not require an Ushuaia origin.

The Schilperoords, passionate birders #

Public identification of the index case was made possible by the decision of Dutch health authorities and statements from the couple's relatives. Leo Schilperoord, 70, and his wife Mirjam Schilperoord, 69, were amateur ornithologists recognised in the Dutch and international birding community. Their multi-month trip to South America was the realisation of a long-standing project.

Mirjam Schilperoord left the MV Hondius on 24 April at Saint Helena, accompanying her husband's body. She fell ill a few days later, taken into emergency care in South Africa after the Saint Helena → Johannesburg flight on 25 April. She died in Johannesburg on 26 April 2026. Her case was initially classified probable, then confirmed by PCR on 3 May.

The couple, publicly identified by their relatives as well as by the authorities, is documented here with respect for family dignity. All information cited is drawn from established press sources (Newsweek, Euronews, NBC News, Infobae, IOL) and official statements.

Key takeaways #

• The Ushuaia landfill hypothesis, first reported by the New York Post on 11 May 2026, is not confirmed by any health authority and is seriously challenged.
• The WHO (Dr Boris Pavlin) points to the Andes Cordillera in northern Argentina or Chile rather than Tierra del Fuego as the more probable area of exposure.
• The temporal argument is the most decisive: 7 days between landfill visit and symptoms, versus a minimum incubation of 9 days.
• The zoological argument (1,500 km south of the known reservoir's range) and the ornithological guide's testimony (no rodents observed over 25 years) reinforce this scepticism.
• The Swiss sequencing confirms a classic South American Andes strain, fully compatible with exposure outside Tierra del Fuego.

To understand the precise role of reservoir rodents in Andes virus transmission, see our article on the long-tailed pygmy rice rat, reservoir of Andes virus. For the complete case timeline, see our timeline page.