Argentina is at the center of an international health investigation following an outbreak of hantavirus aboard the MV Hondius. Authorities are examining a poorhouse on the outskirts of Ushuaia, in the country’s far south, as a possible source of the infection.

According to preliminary findings, a Dutch couple is believed to have been exposed to the virus there during a birdwatching excursion, potentially placing them at the start of the transmission chain. The region attracts many visitors because of its rich birdlife, but the same environmental conditions also favor the presence of rodents that carry the virus.

Hantavirus is transmitted through contact with the urine, saliva, or feces of infected rodents. In the case of the MV Hondius, experts are particularly concerned because the Andean strain — the only known variant capable of human-to-human transmission — has reportedly been identified. This may have contributed to the spread of infections among passengers after the couple boarded the ship.

The outbreak has also renewed attention on Argentina’s withdrawal from the World Health Organization. The country’s exit from the WHO, alongside that of the United States, took effect in mid-March and prompted international criticism.

WHO Director-General Tedros Adhanom Ghebreyesus publicly urged both countries to reconsider their decision. In response, the Argentine government stated that it can continue international cooperation on health matters without being a WHO member. However, the country still maintains technical cooperation with the Pan American Health Organization.

At the center of the transmission of the Andean strain is Oligoryzomys longicaudatus, commonly known as the long-tailed mouse or colilargo. This small wild rodent lives in southern Argentina and Chile and is considered the natural reservoir of the virus.

The species is endemic and protected, playing an important ecological role by dispersing seeds and serving as part of the food chain. Infected animals generally do not show symptoms, but they can transmit the virus to one another, particularly during mating season.

Scientists note that populations of these rodents fluctuate significantly depending on climatic conditions, food availability, and human activities such as deforestation and agricultural expansion.