
SANTIAGO, Chile — A lethal virus carried by rodents infected cruise ship passengers with no available treatments or vaccines to help them, highlighting a critical gap in medical preparedness.
The outbreak involved hantavirus, part of a virus family that scientists have studied for decades and believe exists worldwide. Unlike the novel coronavirus that sparked the pandemic, this pathogen has been recognized for years.
Research groups across Chile, Argentina and the United States have worked extensively to create medications and vaccines. However, because these viruses occur infrequently and rarely transmit person-to-person, governments, global health organizations, and pharmaceutical companies haven’t provided sufficient ongoing funding for comprehensive safety and effectiveness studies required for approval.
Nevertheless, recent developments offer hope. Scientists published findings Wednesday suggesting that a medication for autoimmune conditions might help hantavirus patients combat the most severe complications.
Researchers believe the cruise ship incident — along with concerns that hantavirus cases may increase as climate change brings more human-rodent contact — could generate fresh support for their work.
“I hope this situation will help us continue our research and strengthen the collaboration between healthcare workers, the community, and the necessary resources,” said Dr. Fernando Tortosa of the National University of Río Negro in Patagonia, Argentina, the study’s lead author.
These viruses typically transmit when people breathe in contaminated particles from rodent waste. Different hantavirus species exist globally, each with distinct traits and symptoms.
The Andes virus, responsible for the cruise ship cases, draws particular research attention because it’s the only hantavirus believed capable of human-to-human transmission in certain situations. Though infections remain uncommon, they prove extremely lethal.
“That is why it is a public health problem,” said María Inés Barría, a virologist at the Universidad San Sebastián in Chile who studies hantaviruses.
Among the 13 probable cruise ship cases, three resulted in fatalities. Additionally in Chile, the Ministry of Health has confirmed 15 deaths and 42 cases this year. Argentine authorities have documented 32 deaths and 102 cases since June 2025. In the U.S., 35% of hantavirus cases have proven fatal since monitoring began in 1993, according to the U.S. Centers for Disease Control and Prevention.
Argentine researchers are examining whether tocilizumab, a rheumatoid arthritis treatment, could combat hantavirus pulmonary syndrome, a serious infection from both the Andes virus and Sin Nombre virus found in North America.
Tocilizumab suppresses IL-6, a molecule that causes harmful inflammation in autoimmune and other conditions. IL-6 also appears involved in the inflammatory response to infection, which can quickly cause lung fluid buildup and failure.
Five patients at an Argentine hospital survived after receiving tocilizumab alongside standard hantavirus pulmonary syndrome care, the research team reported in The Lancet Infectious Diseases.
This report documents the first patients treated with tocilizumab in an ongoing “compassionate use” study, allowing doctors to administer it to qualifying patients. Five other eligible patients who received only standard treatment died. Two deteriorated too rapidly, while the hospital lacked supplies for the others, researchers noted.
The research team emphasized that the five patients who didn’t receive the drug were older and sicker than those who did. Still, they concluded tocilizumab deserves additional study.
Barría’s team, including Chilean scientists, U.S. National Institutes of Health Rocky Mountain Laboratories researchers, and Robert Koch Institute scientists from Germany, pursues a different strategy — using cloned antibodies from hantavirus survivors to prevent infections. The team published 2018 research showing animal success, but couldn’t secure funding for human trials, partly because resources shifted to coronavirus pandemic response.
“We are truly at the forefront, at a very important stage of moving to the next phase,” Barría said.
Multiple other groups, including teams at Albert Einstein College of Medicine and Vanderbilt Center for Antibody Therapeutics, also develop antibody treatments.
Vaccines against Old World hantaviruses have been created and utilized, though the World Health Organization states no currently licensed hantavirus vaccines exist. New vaccines are under development, including ones targeting the Andes virus. A team led by Jay Hooper of the U.S. Army Medical Research Institute of Infectious Diseases works on a vaccine that successfully produced antibodies against the virus in early human trials, according to their 2020 study.
Dr. Paul Bollyky, an infectious disease physician and researcher at Stanford Medical Center in California, explained that securing sustained support for rare disease vaccines and treatments like hantavirus proves extremely challenging.
Laboratories typically lack what Bollyky describes as necessary equipment to test and validate vaccines and treatments for uncommon infections. Additionally, because hantavirus outbreaks occur sporadically and unpredictably, studying this virus proves much more difficult than researching common germs like influenza that circulate regularly.
“That also makes clinical trials in this space super difficult because of the number of people you would have to immunize to protect against one infection,” he said. “It’s just impractical.”
This also means limited or inconsistent markets for vaccines or treatments, since predicting exposure timing and populations proves difficult.
Still, researchers and physicians feel frustrated knowing potential treatments could help people now with sufficient sustained investment.
“What happened was a tragedy, but it can happen not only with this but also other diseases,” Tortosa said, referring to the cruise ship outbreak.




































































































































































































