The colilargo spreads the virus everywhere it goes
At the edge of the inhabited world, where Patagonia yields to the Beagle Channel, scientists are asking a question that three deaths have made urgent: did a city unknowingly send a virus to sea? In Ushuaia, Argentina, researchers have spent the past week trapping rodents near the port from which the cruise ship Hondius departed on April first, seeking the colilargo rat — the sole known carrier of the Andes hantavirus strain, and the only hantavirus capable of passing between human beings. So far, the specific animal has not appeared in any of their traps, offering tentative but inconclusive relief to a region that has never, in thirty years of recorded history, confirmed a single hantavirus case.
- Three passengers or crew died from hantavirus Andes after sailing from Ushuaia on April first, forcing the question of whether the port city itself was the origin of the outbreak.
- Scientists deployed 140 traps across three sites — including a landfill suspected as an early infection point — capturing between 40 and 50 rodents daily, yet the critical colilargo rat has not appeared in any of them.
- The Andes strain carries a rare and alarming trait: unlike all other hantaviruses, it can spread directly from person to person, making the identification of its source a matter of urgent public health.
- The two rodent species actually caught — both Abrothrix — can harbor hantavirus but do not shed it at levels that endanger human populations, offering partial but not definitive reassurance.
- Final laboratory results from samples sent to Buenos Aires are expected within three weeks, leaving Ushuaia in a state of suspended judgment — neither exonerated nor implicated.
In Ushuaia, the southernmost city of Argentina, scientists have spent the past week setting traps and collecting rodents in an effort to determine whether this windswept port was the origin of a deadly hantavirus outbreak. Three people died after falling ill aboard the cruise ship Hondius, which departed from Ushuaia on April first. The central question — did the virus board the ship here? — has driven a systematic survey of the city's rodent population.
Roughly 140 traps were distributed across three sites near the city, yielding between 40 and 50 captures per day. But the animal that matters most has not appeared: the colilargo, or Oligoryzomys longicaudatus, the only known carrier of the Andes hantavirus strain. Juan Petrina, who directs epidemiology for Tierra del Fuego province, confirmed the absence at a public briefing. The rodents they have found — two species of Abrothrix common to the region — can carry hantavirus but do not shed it in quantities that create public health risk.
The Andes strain is singular among hantaviruses for one reason: it is the only variant capable of spreading directly between humans, which made the Hondius outbreak especially alarming. A landfill near the city, suspected as a possible site of initial exposure, yielded only a single capture and showed little activity. Researcher Adrián Schiavini noted that the species being caught are among the most ordinary in the region.
Samples have been sent to Buenos Aires for laboratory analysis, with results expected within three weeks. Tierra del Fuego has never recorded a confirmed hantavirus case since mandatory reporting began in 1996 — a history that offers some comfort, though it cannot yet explain what happened aboard the Hondius, or whether Ushuaia bears any part in the answer.
In the southernmost city of Argentina, where the land runs out and the Beagle Channel begins, scientists have spent the past week hunting rats. Not for sport, but for answers. Over a hundred rodents have been trapped and examined in Ushuaia, a windswept port town of eighty thousand people, as researchers try to determine whether a deadly virus outbreak that killed three people aboard a cruise ship originated here before the vessel set sail on April first.
The hunt began in earnest this week, with roughly one hundred forty traps distributed across three locations near the city. Each day, between forty and fifty of those traps have yielded a catch. Juan Petrina, who directs epidemiology and environmental health for Tierra del Fuego province, announced the findings at a public briefing: they have captured rodents, yes, but not the specific kind that matters. The colilargo—a long-tailed rat with the scientific name Oligoryzomys longicaudatus—remains absent from every trap.
This absence is significant because the colilargo is the only known carrier of the Andes strain of hantavirus, a pathogen that has earned a grim distinction: it is the only hantavirus capable of spreading directly from person to person. The other rodents they have found—two species of Abrothrix, common to the region—can harbor the virus, but they do not shed it in quantities that pose a public health threat. The colilargo, by contrast, spreads the virus everywhere it goes, contaminating surfaces and air with lethal efficiency.
The Hondius cruise ship departed from Ushuaia on April first carrying passengers and crew who would soon fall ill. Three people died. The outbreak raised an immediate question: did the virus board the ship in this city, or did it arrive from elsewhere? The scientific mission that began Monday was designed to answer that question by surveying the rodent population that lives in and around Ushuaia. If the colilargo is absent or present only in negligible numbers, it would suggest the outbreak did not originate here. If the rats are abundant and infected, the picture changes entirely.
So far, the traps tell a reassuring story, though an incomplete one. Petrina noted that the colilargo population, at least in the areas they have surveyed, does not appear substantial enough to have been caught in significant numbers. One trap location—a landfill that had been suspected as a possible source of infection for the outbreak's initial case—yielded only a single capture and showed little activity overall. Adrián Schiavini, a researcher at the Austral Center for Scientific Research, explained that the rodents they are finding are among the most common species in the region, and while they may carry hantavirus, they do not transmit it in ways that create public health emergencies.
The samples collected will be sent to Buenos Aires for laboratory analysis. Petrina said final results should be available within three weeks. Until then, the city remains in a state of scientific limbo—not cleared of suspicion, but not condemned either. Tierra del Fuego has never recorded a confirmed case of hantavirus since mandatory reporting of the disease began in 1996. That history offers some comfort, though it does not yet explain what happened aboard the Hondius or whether Ushuaia played a role in the tragedy.
Notable Quotes
The colilargo population, at least in this moment, is not substantial enough to have been caught in the traps— Juan Petrina, director of epidemiology and environment for Tierra del Fuego province
The rodents we found can carry hantavirus, but they do not develop an infection level that creates public health importance the way the colilargo does— Adrián Schiavini, researcher at the Austral Center for Scientific Research
The Hearth Conversation Another angle on the story
Why does it matter whether they find this specific rat, the colilargo? Couldn't other rodents carry the virus too?
They could, and they do. But the colilargo is different—it's the only one that spreads hantavirus between people. The others might harbor the virus, but they don't shed it in ways that create outbreaks. That's the crucial distinction.
So if they don't find the colilargo in Ushuaia, does that mean the virus didn't come from there?
It suggests it didn't, yes. But it's not definitive. The absence of the rat in traps doesn't prove the rat isn't there at all. It just means they haven't caught it yet, or it's not present in the numbers that would make it easy to find.
Three people died on that cruise ship. How does that change what scientists are looking for?
It makes the search urgent and specific. They're not just doing routine surveillance anymore. They're trying to trace the origin of a deadly outbreak. If Ushuaia is where it started, that has implications for the city's reputation, for tourism, for understanding how the virus moves.
What happens in three weeks when the results come back?
They'll know whether any of the rodents they caught are infected. That will either strengthen the case that the virus came from elsewhere, or it will raise new questions about how the outbreak began.