SOUTHERN CALIFORNIA — In May 2026, multiple countries identified cases of Andes hantavirus infection linked to the MV Hondius cruise ship. Individuals affected by this outbreak developed severe respiratory symptoms.
Andes hantavirus is maintained in nature by the long-tailed pygmy rice rat, a rodent native to Argentina and Chile. Human infection primarily occurs through inhaling dust or aerosols contaminated with rodent excreta. The incubation period for Andes hantavirus can extend up to six weeks, with a median duration of approximately 20 days. Andes virus RNA is mainly detected in blood, and less frequently in saliva and nasopharyngeal secretions.
The Epuyen outbreak in Argentina previously provided evidence of person-to-person transmission for Andes hantavirus. However, most introductions of Andes hantavirus do not result in secondary cases, and onward transmission is typically limited to a single close or sexual contact. There is no evidence for asymptomatic spread or seroconversion of Andes hantavirus. Hantavirus diagnosis primarily relies on reverse transcription polymerase chain reaction of blood-derived specimens during the acute phase, with serology supporting the diagnosis.
"The specific strain that we have here in the U.S. is called Sin Nombre virus or SNV," said Dr. Jorge Robledo, an infectious disease physician at Loma Linda University. "This has not been shown to be transmitted from person to person," Robledo said. Sin Nombre virus is carried by the deer mouse. Most U.S. hantavirus cases are caused by Sin Nombre virus, with about 30 people infected annually in the U.S. Infections by hantaviruses kill 30 to 40 percent of infected individuals. Typical household mice in urban settings are not usually carriers of hantavirus.
"Hantavirus is transmitted through contact with urine, with feces, saliva," said Mayo Clinic physician Bobbi S. Pritt. The World Health Organization and the European Center for Disease Prevention and Control assessed Andes hantavirus as posing a low risk to the general public. The Centers for Disease Control and Prevention advises using protective equipment during cleanup if rodent droppings are present. Health officials recommend wetting down rodent droppings with a bleach solution before cleaning and avoiding vacuuming or sweeping to prevent the spread of contaminated particles. "When there's an outbreak or even a case, we need to know where that person was exposed so we can stop other people from being exposed," said Janet Manson, a microbiologist.