CDC Health Update: 2006 Hantavirus Outbreak: Testing for Potential Infection - May 18, 2026

Summary

The Centers for Disease Control and Prevention (CDC) is issuing this Health Alert Network (HAN) Health Update to inform clinicians and health departments about testing available for patients with suspected hantavirus infection to include Andes virus. CDC first issued a Health Advisory (CDCHAN-00528) about this outbreak on May 8, 2026. Hantaviruses are a group of viruses that typically spread to people who come in contact with sylvatic rodents. These viruses can cause severe illness or death in humans. Andes virus, a type of hantavirus endemic in South America, is the only type of hantavirus that is known to spread from person to person. Several other New World hantaviruses are endemic to the United States and are not transmissible from person to person. New World hantaviruses can cause hantavirus pulmonary syndrome (HPS), a potentially serious disease that can cause damage to the lungs.

On May 2, 2026, an outbreak of Andes virus on a cruise ship was reported to the World Health Organization (WHO). This outbreak has raised the possibility of cases being imported to the United States. As of May 18, no confirmed cases of Andes virus associated with the outbreak on the cruise ship have been reported in the United States. Therefore, the overall risk to the American public is still considered extremely low at this time. CDC and health departments in several states are monitoring the health of U.S. passengers from the ship and U.S. air travel contacts of symptomatic ship passengers who were subsequently confirmed to have Andes virus infection. This Health Update informs clinicians about testing and consultation that are available for Andes virus and other hantaviruses endemic to the United States, South America, and other nations.

Background

On May 2, 2026, WHO was notified of a cluster of severe acute respiratory illness (SARI) among passengers and crew aboard the M/V Hondius cruise ship in the Atlantic Ocean. On May 6, 2026, WHO confirmed that the cluster was caused by Andes virus, a hantavirus endemic in areas of South America that can cause hantavirus pulmonary syndrome (HPS). Andes virus is the only hantavirus known to spread from person to person. This type of transmission is rare for hantaviruses and is generally associated with prolonged close contact. As of May 15, WHO has reported 10 cases (8 of them laboratory-confirmed), including 3 deaths.

Hantaviruses cause two syndromes. Hantaviruses found in the Western Hemisphere are often referred to as New World hantaviruses and can cause HPS. Several New World hantaviruses that do not spread person to person are endemic in the United States. These include Sin Nombre virus, the virus mostly commonly associated with U.S. HPS cases. In addition to HPS, hantaviruses can cause other clinically significant illness. Hemorrhagic fever with renal syndrome (HFRS) is a group of clinically similar illnesses that affect the kidneys. HFRS is caused by another group of hantaviruses, often referred to as Old World hantaviruses, that are found mostly in Europe and Asia. However, Seoul virus, a type of hantavirus that causes HFRS, is found worldwide, including in the United States. Non-HPS hantavirus infection can also occur, in which patients experience non-specific viral symptoms without cardio-pulmonary symptoms.

Hantavirus infections can occur year-round but are reported more frequently during the spring and summer months when rodent populations increase and people may have greater exposure to rodent-infested environments such as cabins, sheds, campsites, and homes. The most common hantavirus that causes HPS in the United States is spread by the deer mouse. Andes virus is spread primarily by the long-tailed pygmy rice rat (Oligoryzomys longicaudatus).