They're detecting circulating hantavirus in Ushuaia, but the viral variant doesn't match the one that caused the outbreak on the cruise ship.

The detection of hantavirus circulation in Ushuaia has raised new questions about the presence and spread of this disease in one of the southernmost regions of Argentina. According to recent reports, researchers have identified the virus in rodents captured as part of an investigation into the outbreak aboard the cruise ship *MV Hondius*. This marks the first time hantavirus has been recorded in the province of Tierra del Fuego, which had previously claimed to be free of the virus due to the absence of confirmed cases.

The variant of the virus found in Ushuaia is related to the Andes strain but does not match genetically the strain responsible for the outbreak on the cruise ship. The National Reference Laboratory for the disease, Anlis Malbrán, stated that while the genetic relationship exists, there is no direct link between the two strains. Researchers continue their studies to obtain the full genome of the newly discovered variant and determine its exact identity compared to other known hantaviruses. These findings confirm that the virus detected in Ushuaia is distinct from the one associated with the *MV Hondius* incident.

This discovery means that health authorities in Tierra del Fuego will need to enhance both environmental and epidemiological surveillance, similar to other provinces where the virus is present. Previously, the region was considered free of hantavirus, but now the situation requires more attention. The research team from Anlis Malbrán conducted fieldwork in Ushuaia between May 18 and 22, capturing specimens of the Patagonian long-tailed mouse (*Oligoryzomys longicaudatus*) as part of an epidemiological study linked to the global attention surrounding the *MV Hondius* outbreak.

The *MV Hondius* departed from Ushuaia's port on April 1 heading towards Cape Verde via the Atlantic after several trips to Antarctica, the Falkland Islands, and the South Sandwich Islands. During its voyage, 13 passengers and crew members fell ill, including three who died. The first case was reported in a Dutch ornithologist who had spent five months traveling through Argentina, Chile, and Uruguay in a motorhome with his wife, conducting birdwatching activities.

The Patagonian long-tailed mouse is known to be the reservoir of the Andes virus in endemic areas of southern provinces. It was determined locally that this particular hantavirus can be transmitted from person to person, in addition to the usual environmental route through the urine, saliva, and feces of infected rodents. Although the presence of *Oligoryzomys longicaudatus* had been validated from Neuquén to Tierra del Fuego, there were no previous records of hantavirus in the area.

Researchers from the Southern Center for Scientific Research (Cadic) under CONICET, who monitor the local environment and wildlife, indicated that they had detected DNA of the long-tailed mouse in waters and along the banks of rivers from Ushuaia to Rio Grande. However, captures conducted by Anlis Malbrán within the Tierra del Fuego National Park and other areas outside the city did not yield this species.

Cadic maintains the most comprehensive historical record of the population of long-tailed mice in Tierra del Fuego, dating back to the 1990s. Recently, they have shifted away from using traps and instead use environmental DNA for monitoring purposes in their Molecular Ecology Laboratory. The identification of hantavirus in the island came about through the capture of other rodent species, highlighting the complexity of tracking such diseases in remote and ecologically diverse regions.