Argentina has launched a widening Hantavirus origin investigation after a deadly outbreak aboard the MV Hondius cruise ship left three passengers dead, others critically ill, even as international health authorities are racing to trace how a rare rodent-borne virus may have spread across continents.
Officials say the focus is now on whether the infection began in South America before passengers boarded the vessel in Ushuaia in April 2025.
Authorities in several countries are now keeping an eye on passengers who have already left the cruise ship and returned home, including some who are believed to have travelled back to the United States.
Health teams are trying to trace where these people have been and who they may have come into contact with since leaving the MV Hondius.
The World Health Organisation says it is still watching the situation closely, but stresses that the risk to the wider public remains low.
Argentina, where the cruise began, has long had the highest number of Hantavirus cases in Latin America, according to the WHO.
The MV Hondius, a Dutch cruise ship heading to Antarctica, became a concern after several infections were confirmed on board. That led to emergency evacuations and coordination efforts involving health authorities across at least 5 countries.
Origin Points To Argentina's Rodent-Rich Regions
The Guardian reported that Argentine health officials are focusing on whether passengers may have contracted the virus before boarding the ship in Ushuaia, a southern port city often called the gateway to Antarctica. The country's health ministry has reported 101 Hantavirus cases since June 2025, about double the number from the year before, officials say, a worrying rise.
Hantavirus, especially the Andes strain found in South America, can cause a serious lung disease called Hantavirus pulmonary syndrome. Health officials say that in the past year, nearly one in three infected people died from it in Argentina.
Investigators are now trying to piece together exactly where passengers went before boarding the MV Hondius on 1 April 2025. Some are reported to have travelled through Argentina, Uruguay and Chile in the days before the cruise, which makes it harder to determine where exposure may have occurred.
One of the difficulties is timing.
The virus can take anywhere from one week to two months to show symptoms, meaning someone could have been infected long before they felt unwell. That leaves several possible points of exposure, from rural areas where rodents are more common, to busy cities or even early days on the ship.
Authorities are also closely examining 23 passengers who left the ship at Saint Helena in April. Some of them are believed to have returned to their countries, including the United States. Health teams are now monitoring them, although no illnesses have been confirmed among that group so far.
Global Response To Hantavirus
The investigation has now spread well beyond Argentina, with health agencies in different countries working together to track passengers who have already left the cruise ship. The WHO says at least three people have died in connection with the outbreak, either on the ship or shortly after leaving it. This includes a 70-year-old Dutch man who became ill in April, his wife, who later died in Johannesburg, and a German passenger who died in early May.
Another case has also been confirmed in Switzerland, where a passenger tested positive after leaving the ship earlier in the journey, making it harder for investigators to map exactly how the virus spread.
WHO director-general Tedros Adhanom Ghebreyesus said the organisation is working with governments and the cruise operator to ensure people receive medical care and are evacuated when necessary. He also said that the monitoring of passengers and crew has already started in several countries.
Argentina has begun sending samples of the Andes strain of the virus to laboratories in Spain, South Africa, Senegal, the Netherlands, and the United Kingdom. The idea is to help other countries detect infections more quickly if cases appear.
At the same time, questions are being raised about how quickly passengers were followed up with after leaving the ship. Reports suggest some people who disembarked in Saint Helena were not contacted immediately. One account, reported in Spanish media, claimed that some passengers were left 'wandering around' before tracing systems were fully in place, although officials have not confirmed this.
Climate And Environmental Factors
As the investigation into the Hantavirus's origin continues, scientists in Argentina are also examining whether environmental changes could be helping the virus spread by affecting rodent populations that carry it.
Infectious disease expert Hugo Pizzi has suggested that rising temperatures may be expanding areas where these rodents can survive. He also said that changing ecosystems can increase food sources for rodents, which may increase the risk of human contact in some regions.
Argentina has also seen increases in other diseases linked to climate conditions, including dengue and yellow fever. This has added to concerns that environmental changes may be influencing public health risks more broadly.
Even so, experts stress that Hantavirus is usually spread through contact with infected rodents or their droppings, urine, or saliva. Human-to-human transmission is rare, although it has been seen in limited cases involving the Andes strain.
Investigators are still trying to pull together travel records, test results and possible exposure points. With passengers spread across different countries and a long incubation period for the virus, officials say it may take time to fully understand where the outbreak began, if it can be identified at all.
