Argentine Investigators Trap Rodents in Search for Hantavirus Outbreak Source

Argentine investigators are now trapping rodents in forests near Ushuaia, a city in the country's southernmost region, as they search for the source of a deadly hantavirus outbreak. This fieldwork aims to detect the rat-borne virus in an area previously believed to be unaffected.

Scientists, clad in bright blue gloves and surgical masks, were seen checking 150 box traps set the previous night. They carefully placed dead rats into black plastic bags, which were then loaded onto pickup trucks destined for a makeshift laboratory. There, blood samples will be drawn from the rodents.

This rat-trapping operation, which began on Tuesday, marks the initial phase of Argentina's broader inquiry into the contagion's origin. The outbreak struck the MV Hondius last month, resulting in three fatalities and sickening several others, prompting a global effort to trace passengers and their close contacts. Investigators, navigating muddy terrain, declined to comment on their work.

The state-backed Malbrán Institute, Argentina’s leading research center for infectious diseases, said the team would repeat the routine for the next three days before returning with the samples to the institute’s main Buenos Aires laboratory to test for hantavirus. Testing could take up to one month, but officials were tight-lipped about further details.

“They were able to capture what was expected,” said Martín Alfaro, the spokesperson for the local health ministry of Tierra del Fuego.

The effort comes almost two weeks after the Argentine Health Ministry first announced it would send the team from the Malbrán Institute to Ushuaia. The popular tourism destination where the cruise departed — famed for its location at the “end of the world” — serves as the main gateway to the Antarctic.

Questions surround Argentina's investigation

The hantavirus has never been recorded in Ushuaia or the wider archipelago of Tierra del Fuego. But provincial officials further north in Patagonia where the hantavirus is endemic insist that the first known victims of the outbreak — a Dutch couple passionate about birds — didn't visit during the window in which it is believed they got infected.

The Dutch tourists concluded a sprawling road trip across Chile and Argentina in late March with a few days of bird-watching and trekking in Ushuaia before boarding the ship April 1.

Health authorities here have fiercely rejected the national government’s initial hypothesis that the chain of infections on the cruise began when the couple visited an Ushuaia landfill. They have both since died, complicating the efforts of Argentine investigators to retrace their path through the country with the aim of determining where they contracted the virus.

Found throughout southern Chile and Argentina, the Andes virus may be able to spread between people in rare cases. Most clusters of the Andes virus, experts say, emerge from exposure to air contaminated with the feces and urine of the long-tailed pygmy rice rat known as the “colilargo" that runs rampant through the forests of northern Patagonia.

The colilargo itself has no presence across the Strait of Magellan in Tierra del Fuego, which is believed to be too cold and isolated for the rat. But a subspecies can be found in the forests around Ushuaia, and scientists have never examined whether it can transmit the hantavirus.

Adamant that tourism-dependent Tierra del Fuego isn't the source of the cruise ship outbreak, health authorities here say they welcome a broader objective of the investigation: figuring out if their province has hantavirus at all at a time of global warming. They said the scientists were trapping rats in two areas where the colilargo subspecies proliferates — the national park and the wooded hillsides overlooking Ushuaia’s main pebble beach.

“The province has never done this kind of testing before,” Alfaro said. “It's important that we rule out the possibility of transmission occurring here.”

The number of hantavirus cases has increased in recent years in Argentina, a trend scientists attribute to colilargos vastly increasing their range as a result of climate change and human encroachment.