Hantavirus is garnering attention after a rare but high-consequence cluster of cases linked to an outbreak on a cruise ship. The cases involved severe respiratory and gastrointestinal illness and intensive care admissions among passengers. As of May 26, the outbreak has been linked to 13 cases (11 confirmed and two probable) among passengers, including three deaths.
What makes this outbreak notable is not the widespread transmission, but its occurrence in an unusual high-mobility setting, far removed from the rural rodent-associated environments where hantavirus is typically encountered. Rodent-to-human transfer is the usual mode of infection.
Despite lacking pandemic potential, hantavirus infection can be clinically severe and presents diagnostic challenges. This makes it crucial to prioritize early detection, timely laboratory preparedness, and strengthened surveillance in an increasingly interconnected global environment.
What is hantavirus?
Hantaviruses are enveloped RNA viruses belonging to the family Hantaviridae. They were first identified amid Korean hemorrhagic fever outbreaks among United Nations troops following the Korean War (1951–1953). In 1978, Hantaan virus was first isolated in South Korea from striped field mice (Apodemus agrarius) near the Hantan River. In the mid-1980s, hantaviruses were recognized as a distinct genus—Hantavirus—within the family Bunyaviridae, distinguished by their rodent-only reservoirs and the absence of arthropod vectors.
How does hantavirus spread?
Rodents are the primary natural reservoirs for pathogenic hantaviruses. Each hantavirus is typically associated with a specific rodent host species. These viruses in rodents can often cause persistent but asymptomatic infections. Zoonotic spillovers, or rodent-to-human transmission, occur when people are exposed to environments contaminated with urine, droppings, or saliva from infected rodents. Less commonly, infections can also result from direct contact with rodents or rodent bites. Human-to-human transmission is uncommon, except for rare cases involving Andes viral strain, where rare and sporadic incidences have been reported in closed settings.
What are the symptoms of hantavirus infection?
In the western hemisphere, hantavirus infections can lead to hantavirus pulmonary syndrome (HPS), which is considered a potentially fatal disease. Symptoms start to occur between one and eight weeks post exposure. Main early symptoms of HPS include fatigue, fever, chills, muscle ache, and gastrointestinal problems. Around the first week after initial symptoms, during the later phase, shortness of breath and bouts of cough start to occur due to severe lung infection. This can further lead to respiratory failure and shock. Nearly one-third of infected patients who develop respiratory symptoms from hantavirus infection may die from the disease.
In Europe and Asia, hantavirus infections result in hemorrhagic fever with renal syndrome (HFRS), which mainly affects kidney functions. Early symptoms start to develop within 15 days after exposure. In some cases, symptoms are delayed and can appear as late as eight weeks post exposure. Some main initial symptoms are headaches, back pain, abdominal pain, nausea, blurred vision, redness of eyes, rashes, and flushing of the face. Main later symptoms are internal bleeding, low blood pressure, and acute kidney failure.
According to UN agencies, the 2026 cruise ship outbreak was attributed to the Andes virus strain, and the clinical presentation among infected passengers was consistent with HPS.
Timeline of the MV Hondius hantavirus outbreak: key cases, deaths, and public health updates. (CDC = US Centers for Disease Control and Prevention; HAN = Health Alert Network; IHR = International Health Regulations; WHO = World Health Organization.)
Today's Clinical Lab/Hertelendy AJ et al. JAMA. May 26, 2026. doi:10.1001/jama.2026.10321
Current hantavirus testing methodologies and guidelines
Early clinical manifestation of HPS and HFRS are notoriously nonspecific, and symptoms often overlap with a broad range of infectious diseases, including gastrointestinal infections, influenza, and dengue. Reliable clinical diagnostic methods are thus crucial for enabling early detection and minimizing further spread within the community.
Currently, diagnosis of hantavirus infection is performed mainly via serologic and molecular methods. IgM and IgG enzyme-linked immunosorbent assays (ELISA) remain the primary method for initial laboratory detection.
In addition, PCR-based testing is increasingly being employed because of its higher sensitivity and specificity, enabling detection of viral RNA during the initial stages of infection. In outbreak contexts, genomic sequencing can also play a key role in strain characterization and epidemiologic mapping.
Hantavirus prevention
Primary prevention strategies for hantavirus involve rodent control and environmental decontamination, including:
- Keeping the rodents out of houses and enclosed places (cabins, shed, barns, vehicles)
- Avoiding aerosol-generating activities, such as dry sweeping in potentially contaminated environments
- Using disinfectants or bleach solution to wet the area before cleaning with a sponge or mop
- Wearing appropriate PPE (gloves and masks), while performing all above-mentioned tasks
Hantavirus treatment
There is currently no specific antiviral therapy approved for hantavirus infection. Patient management is therefore entirely supportive, and worsened symptoms lead to early escalation to intensive care.
Some crucial interventions for hospitalized patients include respiratory support with oxygen or mechanical ventilation, careful hemodynamic stabilization using vasopressors, and judicious fluid management to avoid worsening pulmonary edema. In severe HPS cases, extracorporeal membrane oxygenation (ECMO) may be required to support cardiopulmonary function. Hospitalized patients with severe HFRS symptoms require close monitoring of their renal functions and dialysis in some cases.
Many antiviral drugs, including Ribavirin and Favipiravir, have demonstrated limited efficacy in HFRS but has not shown clear benefit in HPS.
Several hantavirus vaccine candidates have demonstrated the potential to provide durable and long-lasting immune protection in preclinical and early clinical trials. However, no globally approved vaccine is currently available. Ongoing clinical research also focuses on improving vaccine efficacy, safety, and broader protection against multiple hantavirus strains.
Can hantavirus lead to the next pandemic?
Despite its severity and high mortality rate, experts consider it unlikely that hantavirus will cause a pandemic, given that it lacks key biological and epidemiological features required for sustained human-to-human transmission. The most notable limiting factor is inefficient zoonotic spillover to humans. Except for rare Andes virus-associated clusters, there is no evidence of sustained human-to human transmission in community or healthcare settings. In addition, hantaviruses are highly host-specific to rodent reservoirs, limiting spillover events and reducing transmissibility in human populations.
Key differences between hantavirus and past pandemic-causing viruses include:
- Unlike viruses of pandemic potential (like influenza and SARS-CoV-2), hantaviruses do not demonstrate asymptomatic clinical presentations.
- Transmission rate (basic reproduction number, R₀) and mutation rate of hantavirus is much lower than influenza or SARS-CoV-2, which makes hantavirus infections self-limiting and less transmissible.
- The incubation period for hantavirus is much longer than influenza or SARS-CoV-2, meaning hantavirus infections are easier to contain.
Continued surveillance and monitoring remain important given the evolving nature of zoonotic pathogens like hantavirus.
Smarter outbreak detection
This recent hantavirus outbreak underscores important lessons for the clinical testing landscape. In travel-related cases presenting with influenza-like illness and gastrointestinal symptoms, and where routine test results are negative, rare zoonotic testing should be considered.
Laboratories maintain rapid access to resources and testing infrastructure for high-impact infections. During these outbreaks, integration of laboratory data with clinical and public health surveillance systems supports identification of infection hotspots and strengthens national-level surveillance, which is crucial for limiting broader transmissions.
