Hantaviruses are a group of global zoonotic, single-stranded, tri-segmented, negative-sense RNA viruses within the Orthohantavirus genus. They are generally divided into 2 groups, New World and Old-World hantaviruses, based on geographic distribution. Sin Nombre virus, a New World hantavirus, is endemic in the U.S., and Andes virus, also a New World hantavirus, is found in South America. Andes virus is the species associated with May 2026 multinational outbreak on a cruise ship. Both the Andes virus and the Sin Nombre virus can cause Hantavirus Pulmonary Syndrome [HPS, alternatively hantavirus cardiopulmonary syndrome(HCPS)] in humans, but only the Andes virus can be transmitted person-to-person through close contact.

In an effort to address diagnostic questions that clinical laboratories may have, ASM and APHL jointly developed an FAQ document for clinical laboratories on hantavirus testing.