Pathologists Address Hantavirus Concerns

Hantavirus is typically diagnosed through blood tests that detect antibodies that the immune system produces in response to the virus. It can also be diagnosed using PCR-based testing to detect viral RNA in blood. In some cases, these molecular tests may be more sensitive during the earliest stages of infection and can detect infection before symptoms or antibodies are noticeable; however, the PCR-based tests are usually only available in public health or reference laboratories.

Pathologists play an important role in diagnosing hantavirus infection and helping guide appropriate patient care. Through laboratory testing and collaboration with clinical teams and public health partners, they help identify cases, support accurate diagnosis, and contribute to efforts to monitor and limit the spread of infection.

Andes hantavirus is the most common hantavirus causing human infection in South America. It is also the only hantavirus strain for which person-to-person transmission has been clearly documented, which is why public health officials monitor it closely during outbreaks. It can cause a severe respiratory illness known as Hantavirus Cardiopulmonary Syndrome, which can be life-threatening—it has a mortality rate of approximately 40%. Infections are rare but can be serious, and there is no specific antiviral treatment or widely available vaccine, which is why early recognition and supportive medical care are important.

Early symptoms of hantavirus—such as fever, fatigue, headache, and muscle aches—resemble many other viral illnesses. And antibody tests may not detect an infection until symptoms are well-developed, making an early diagnosis more challenging.

Hantavirus behaves very differently from COVID-19, which spreads efficiently through respiratory droplets and aerosols. In contrast, hantavirus is not considered highly transmissible; the person-to-person spread of hantavirus is rare and requires close, prolonged contact.

Most hantavirus infections occur after exposure to infected rodents or their droppings, particularly by inhaling contaminated particles. Person-to-person transmission has only been documented with certain strains, such as Andes hantavirus; even then, transmission is rare and appears to require close and prolonged contact, such as direct caregiving or other sustained close interactions. It does not spread efficiently through casual interaction and is not considered highly contagious. Although the virus has been detected in body fluids, including blood, saliva, urine, and semen, the precise mechanism of transmission between people has not been definitively established.

While hantavirus infections occur in different regions of the world—including the US, where cases are typically associated with the Sin Nombre virus—infections are rare in the States, and are most often linked to environmental exposure to infected rodents rather than person-to-person transmission.

For travelers, general measures to prevent infection—including good hand hygiene, cleaning frequently touched surfaces, and avoiding close contact with people who are visibly ill—remain effective. They should also avoid contact with rodents or areas that may be contaminated by rodent droppings, as such exposure leads to the highest risk of hantavirus infection. The risk of infection to the general public remains low, but people in certain occupational settings or those spending time in areas where rodents are present remain at increased risk.

Close-quarters environments can make it easier for some infectious diseases to spread because people are in prolonged contact in shared spaces. However, there is no evidence that hantavirus spreads efficiently through casual contact in these settings. It does not spread efficiently like respiratory viruses such as COVID-19 or influenza; rather, transmission (when it occurs) appears to require close and prolonged contact rather than brief or incidental exposure.

The current cruise ship situation appears to be a rare event, and there is no indication that there is an increased risk of hantavirus outbreaks on other ships. Travelers should always be aware of general health risks in crowded environments but do not need to avoid cruise travel specifically because of hantavirus.

Public health officials will monitor exposed individuals and implement precautions to reduce transmission. While additional cases may occur among close contacts, the overall risk of widespread transmission and broader community spread is low. Past outbreaks—even the largest documented outbreaks of Andes hantavirus—have involved relatively small numbers of cases, and public health measures are effective at limiting further spread.