Viral Geography August 25, 2026 The Junín virus binds to receptors on a respiratory tract cell, starting the process that allows it to penetrate inside. When colleagues called in the infectiologist Matías Lahitte, the useful window had almost closed. In Rosario, in the heart of a large city, a 65-ye…
Viral Geography
August 25, 2026
The Junín virus binds to receptors on a respiratory tract cell, starting the process that allows it to penetrate inside. When colleagues called in the infectiologist Matías Lahitte, the useful window had almost closed. In Rosario, in the heart of a large city, a 65-year-old woman had high fever, muscle pain, deep exhaustion; her white blood cells and platelets had fallen to dangerous levels. Less than a week later she was dead. The tests finally gave a name to the disease: Argentine hemorrhagic fever, caused by the Junín virus. The point is not just that a woman died of a preventable and curable disease. The point is that that woman should not have been there — at least according to the image we had of the typical patient for decades. She did not work in the fields, she did not lead a rural life, she was not part of that agricultural and male world to which Argentine hemorrhagic fever had been almost automatically associated. She lived in the center of Rosario. Where she encountered the virus we do not know, and it would be wrong to turn a single case into proof of urban transmission. But it would be equally imprudent not to see the anomaly. Sometimes it is precisely the detail that does not fit that tells us that the old map no longer suffices. The story, reconstructed on August 21 by Zane Irwin and Lucía Cholakian Herrera in The New York Times, actually begins far from hospitals, among grass, disturbed earth, railway tracks, abandoned lots. The main natural reservoir of the Junín virus is a small rodent, the Calomys musculinus. Infection occurs mainly when contaminated particles from its urine, saliva or feces are breathed in or reach the skin and mucous membranes. The passage from person to person is possible, but it is not the usual way in which the virus advances. At first, the disease does not show its face immediately. Fever, headache, nausea, muscle pain, weakness: common symptoms, almost anonymous, capable of blending in with those of many other infections. It is this initial banality that makes the mechanism more insidious. If the diagnosis is delayed, hemorrhages, convulsions, neurological disorders, coma can arrive. First a nameless malaise; then the aggravation; then, when finally Junín is thought of, the lost time. In the case of Rosario exactly this happened: the diagnosis arrived when the possibility of intervening had already narrowed down. The numbers remain small, but not for that harmless. Until epidemiological week 37 of 2025, the Argentine Ministry of Health had confirmed 49 cases out of 492 reports and three deaths: 18 cases in the province of Buenos Aires, 16 in Santa Fe, 15 in Córdoba. The most evident increase was recorded in Córdoba; Buenos Aires and Santa Fe remained instead within the expected values. Adding the data reported for 2024 and 2025, at least nine deaths had been recorded. Nine may seem few only as long as they remain a figure. They become many when we know that timely diagnosis can radically change the outcome of the disease. But who are the sick today? In the consolidated national data for 2024, among the 49 confirmed cases, 33.67 per cent concerned people working in urban areas; just 4 per cent were engaged in rural activities. According to the authorities of Santa Fe, it is the confirmation of an epidemiological change observed since 2010.
It doesn't mean — let's not stop at the easy formula — that the virus has suddenly 'adapted to the city'. It means rather that the city has pushed its boundaries towards the countryside and that the countryside, through uncultivated land, railways and degraded areas, has insinuated itself into the city. The border that we thought was clear has become porous. Let's look at those peripheries: houses and human activities advance on spaces that were once agricultural; rodents find shelter along the tracks, in the gaps left by construction, in the strips of forgotten land between one district and another. Where does the rural area end then? Where does the urban one really begin? These are concrete questions, not geography exercises. If we continue to look for the disease only in the old landscape, we risk not recognising it when it changes direction. A study published in April on npj Viruses tried to broaden our perspective, integrating climate, land use, human density and the distribution of six species of rodents. For the period 2041-2060, the models predict a shift and, in various areas, an expansion of the risk that South American arenaviruses will pass to humans. This is an ecological prediction, not the demonstration that climate change has caused today's cases. The distinction matters: understanding a possible chain does not mean pretending to have already tried every link. But ignoring it because it is not yet a certainty would be another way, more elegant and no less dangerous, of arriving late. Argentina, fortunately, is not unarmed. It possesses the Candid #1 vaccine, administered in a single dose to those who live, work or travel in endemic areas. And it possesses the immune plasma of recovered people, which, if used early on, can reduce mortality from levels capable of reaching 30 per cent without treatment to around 1 per cent. Between those two extremes there is no miracle: there are the suspicion of a doctor, available supplies, a surveillance network that does not exclude cities and peripheries, the speed with which one recognises what no longer corresponds to the manual. No, Argentine haemorrhagic fever is not today 'the next pandemic'. Junín does not easily pass from one human being to another and its spread remains geographically confined. It's not necessary to mount the trailer of a new global emergency. What's needed is something more difficult: paying attention without giving in to panic, expanding surveillance without distorting facts, accepting that zoonoses do not always present themselves with thousands of patients and screaming headlines. Sometimes they enter the radar as weak signals: a 65-year-old woman who lives in the centre of Rosario, the rustling of a rodent along a railway line, a fever mistaken for something else. And if we wait for those signals to become noise, the useful window may already be closed. Kulkarni PS, Flores-Pérez NY, Jian AH, et al. Climate-driven changes in zoonotic risk of arenaviral hemorrhagic fevers in South America. npj Viruses. 2026;4:23. Published on April 15, 2026. doi:10.1038/s44298-026-00189-2. Digital edition Mondosanità is a registered journalistic title with the Torino Court of Registry Registration N. 11/2020 of 23/05/2020. Except where otherwise indicated, all Mondosanità content is released under the 'Creative Commons Attribution - Non-commercial - No derivative works 3.0 Italy License'. Registration number ROC 34464. Publisher: Editoriale Mondo Cooperative Society | C.F. and P.I.
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