Researchers Test Arthritis Drug for Hantavirus After Cruise Ship Outbreak

Researchers in Argentina reported that four of five patients survived hantavirus pulmonary syndrome after receiving the rheumatoid arthritis drug tocilizumab along with standard care. Five other patients who received only standard care died, though the research team noted the untreated group was older and sicker.

The findings were published Wednesday in The Lancet Infectious Diseases as part of an ongoing compassionate-use study. The drug targets IL-6, a molecule linked to damaging inflammation that can cause rapid lung failure in severe hantavirus cases.

The Andes virus, which caused the cruise ship outbreak, is the only hantavirus thought capable of spreading between people in some cases. Three of 13 likely cases among passengers ended in death. Chile's Ministry of Health has confirmed 15 deaths and 42 cases so far this year.

Argentina has reported 32 deaths and 102 cases since June 2025. In the United States, 35 percent of tracked cases since 1993 have been fatal. Hantaviruses spread when people inhale contaminated rodent droppings. The viruses are known worldwide but rarely cause sustained human-to-human transmission.

A Chilean-led team including scientists from the U.S. National Institutes of Health and Germany's Robert Koch Institute is developing cloned antibodies from survivors to prevent infection. The approach worked in animals in 2018 research, but human trials stalled after funding shifted to coronavirus work.

Other groups at Albert Einstein College of Medicine and Vanderbilt Center for Antibody Therapeutics are also pursuing antibody treatments. A U.S. Army Medical Research Institute team reported in 2020 that an experimental vaccine generated antibodies against the Andes virus in early human trials.

Researchers said sustained investment is difficult because outbreaks are sporadic and the potential market for treatments is small. One infectious disease specialist noted that clinical trials require immunizing large numbers of people to protect against rare infections.