A retrospective walkthrough of what hantavirus surveillance looked like in 2024 — the Argentina Patagonia case rise, the steady Sin Nombre virus US background, the Yosemite reference cluster, and how the 2024 picture set the ecological and epidemiological context for the 2026 MV Hondius cluster.
The short answer is no, not in the formal WHO Disease Outbreak News sense. 2024 produced no single declared hantavirus outbreak across the major surveillance systems. What 2024 did produce was a measurable rise in Andes virus case reports from rural Patagonia in Argentina, a steady background of Sin Nombre virus cases in the American West, and a stable HFRS picture in Eurasia. The Argentine rise — which is the operative 2024 trend signal — is the one that retrospectively sits closest to the 2026 MV Hondius cluster.
The defining hantavirus signal of 2024 was the Argentine Andes virus case rise. The Argentine Maiztegui Institute, the national reference laboratory, reported a cumulative count for the year that ran roughly double the historical baseline, with most cases concentrated in rural Río Negro, Chubut and Neuquén provinces in southern Patagonia. The published explanation centred on favourable rodent-reservoir conditions: warmer wet seasons, expanded long-tailed pygmy rice rat range, and the agricultural cycle that puts rural workers in close contact with rodent burrows during spring planting. The 101-case figure that circulated in May 2026 cluster reporting traces directly to this rise.
The United States in 2024 looked broadly consistent with the published Sin Nombre virus baseline. The CDC reported HPS cases in the single digits to low double digits across the Four Corners endemic states (New Mexico, Arizona, Colorado and Utah), with the standard mix of rural cabin cleanup, outbuilding exposure, and agricultural workplace incidents accounting for the majority of cases. No single cluster crossed the threshold for a formal investigation. The published baseline matters because it is the comparator against which the 2026 cluster is being interpreted — the receiving-country US cohort at UNMC Omaha and at Emory Atlanta is being held against a quiet US background year.
The Yosemite cluster is not a 2024 outbreak — it occurred in 2012 — but it returned to relevance in 2024 retrospective writeups and again in 2026 cluster commentary. Ten visitors who stayed in signature tent cabins at Curry Village, Yosemite National Park developed Sin Nombre virus HPS in summer 2012; three died. The cluster sits in the published literature as the canonical short-stay tourist-accommodation hantavirus cluster, and it is the comparator the 2026 MV Hondius cluster is now repeatedly held against in lessons-learned commentary on how a single shared accommodation environment can seed a multi-country case set.
The Eurasian hemorrhagic fever with renal syndrome picture in 2024 was broadly stable. China reported HFRS in the low thousands of cases for the year, consistent with the published baseline; Russia and the Balkans reported Puumala and Dobrava cases in line with their multi-year averages. 2024 did not produce a notable Eurasian cluster, and the absence of an Old World hantavirus 2024 signal is part of why the 2026 cluster — entirely a New World Andes virus event — has not triggered Eurasian surveillance escalation.
The retrospective read on 2024 in light of the 2026 cluster is straightforward. The Argentine Patagonia rise gave the WHO working hypothesis its environmental origin: an index case acquiring Andes virus from rural environmental exposure in Argentina before boarding the MV Hondius. The genomic sequencing now underway at INRB Kinshasa, NICD Johannesburg and Geneva University Hospitals, comparing the cluster isolates with the Argentine Maiztegui Institute reference archive, is the laboratory test of that hypothesis. The Sin Nombre US background and the Eurasian HFRS picture were quiet enough in 2024 that the cluster, when it appeared, was unambiguous as an Andes-virus event rather than a coincidence with another lineage.
2024 was a quiet year on the hantavirus calendar by the standards of the published surveillance systems. The single trend signal was the Argentina rise. That trend signal — at the time it was reported — was not interpreted as a near-term risk for a multi-country cluster. The 2026 MV Hondius cluster is what brought the Argentina trend back into focus, and the operating lesson from the 2024 retrospective is that elevated rodent-reservoir activity in a known endemic region produces tail-risk exposures that conventional surveillance is poorly placed to forecast.
There was no single declared hantavirus outbreak in 2024 in the formal WHO Disease Outbreak News sense. What 2024 did show was a measurable rise in Andes virus case reports from rural Patagonia (Argentina) and a steady background of Sin Nombre virus cases in the American West. The Argentina rise — reflected in the 101-case figure circulating in May 2026 cluster reporting — set the demographic and ecological context for the 2026 MV Hondius cluster.
There is no single published global hantavirus 2024 death figure. National surveillance systems run independently: the US CDC reports HPS deaths in single digits per year, Argentina reports HPS deaths in the low double digits per year, and the Eurasian HFRS systems report deaths in the low thousands per year. 2024 was broadly consistent with this published baseline; no single 2024 cluster crossed the WHO Disease Outbreak News threshold.
The Yosemite outbreak refers to the 2012 Sin Nombre virus cluster at Curry Village, Yosemite National Park, in which ten visitors who stayed in signature tent cabins developed HPS and three died. The Yosemite cluster sits in the 2024 retrospective literature as the canonical short-stay tourist-accommodation hantavirus cluster — the comparator the 2026 MV Hondius cluster is now repeatedly held against in lessons-learned writeups.
Yes. Argentina reported an increase in Andes virus cases in rural Patagonia through 2024 and into 2025, with cumulative case counts roughly double the historical baseline. The Argentine Maiztegui Institute, the national reference laboratory for hantaviruses, attributed the rise to favourable rodent-reservoir conditions including warmer wet seasons and expanded long-tailed pygmy rice rat range. The 101-case figure circulating in 2026 cluster reporting tracks this rise.
No single declared 2024 Four Corners outbreak occurred. The Four Corners region remains the canonical Sin Nombre virus endemic zone in the United States, with a steady low background of HPS cases reported across New Mexico, Arizona, Colorado and Utah. 2024 was consistent with the published US background, with most cases tied to rural cabin or outbuilding exposure during spring cleanup.
The 2024 baseline is largely a quiet-year endemic baseline — Argentina trending up, US background unchanged, Eurasia stable. The 2026 MV Hondius cluster is qualitatively different: a single-source maritime cluster with documented human-to-human Andes virus transmission across roughly 20 receiving countries. The 2024 baseline did not predict the cluster; the Argentina rise provided the ecological context the index case is hypothesised to have acquired the virus from.