Everything You Need to Know About Hantavirus: Outbreaks Symptoms Prevention and Latest Research

Hantavirus was once considered a rare, regional threat. Not anymore. Cases across the Americas hit a six-year high in 2025, a cruise ship outbreak made international headlines in 2026, and researchers are racing to develop the first-ever vaccine. Here is what you need to know right now.

Recent Outbreaks: A Rapidly Changing Picture

The past two years have marked a turning point in hantavirus activity worldwide. Cases are rising, and the geographic spread is widening.

Argentina has been hit hardest. Starting in June 2025, the country saw a sharp surge in cases. By May 2026, Argentina had recorded 101 confirmed cases and 32 deaths, nearly double the figures from the previous season. Buenos Aires province alone accounted for 42 cases.

Across the broader Americas region, eight countries reported 229 cases and 59 deaths in 2025, a case fatality rate of nearly 26%. Bolivia saw its case count double compared to its two-year average, while Paraguay reported 27 cases.

In the United States, 2025 brought 38 confirmed cases, a six-year high and a 192% increase from 2022 levels. New Mexico, Arizona, and California led the count.

Then came the most unusual outbreak in recent memory. In May 2026, the WHO confirmed a cluster of hantavirus cases aboard the cruise ship MV Hondius in the South Atlantic. The ship had visited Antarctica, South Georgia, and Argentina. By mid-May, 11 cases had been confirmed with 3 deaths. What made this outbreak especially alarming was the strain involved: the Andes virus, the only hantavirus known to spread between people.

How Hantavirus Spreads

Understanding how hantavirus is transmitted is key to protecting yourself. The virus lives in infected rodents and reaches humans in three main ways:

• Inhaling airborne particles from infected rodent urine, droppings, or saliva is the most common route. This typically happens when disturbing rodent nests or cleaning enclosed spaces like cabins, sheds, or storage areas.

• Touching contaminated surfaces and then touching your nose or mouth can also transmit the virus, though this route is less common.

• Rodent bites carry risk, though rare.

• Person-to-person transmission is only possible with the Andes virus strain, found in South America. It spreads through prolonged close contact, direct physical contact, or exposure to respiratory droplets.

Climate change is amplifying the risk. New research models show that shifting weather patterns have expanded rodent ranges and pushed humans into closer contact with wildlife, which is a key driver behind the recent surge in South America and beyond.

Symptoms: What to Watch For

Hantavirus Pulmonary Syndrome (HPS) progresses in two distinct phases. Catching it early is difficult because the initial symptoms resemble the flu.

Phase 1 (Days 1 to 7):

• Fatigue, fever, and intense muscle aches, especially in the thighs, hips, and back

• Headaches and dizziness

• Chills

• Nausea, vomiting, or diarrhea in about half of patients

Phase 2 (Days 4 to 10):

• Sudden onset of coughing and shortness of breath

• Lungs begin to fill with fluid

• Rapid deterioration requiring intensive care

The incubation period is typically one to eight weeks. For the Andes virus specifically, health authorities now use a 42-day monitoring window. The fatality rate for HPS ranges from 38% to 40%, making early medical attention critical. If you have been in areas with rodent activity and develop these symptoms, seek care immediately and tell your doctor about the potential exposure.

Prevention: Practical Steps That Work

There is no vaccine or specific antiviral treatment for hantavirus. Prevention is the only reliable defense. The CDC and WHO recommend the following measures:

At home and at work:

• Seal cracks, gaps, and holes in walls, floors, and foundations to block rodent entry

• Store food, including pet food, in sealed, rodent-proof containers

• Set traps around the home and check them regularly

• Keep clutter and debris away from the exterior of your home to reduce nesting spots

When cleaning rodent-contaminated areas:

• Never sweep or vacuum rodent droppings. This aerosolizes the virus.

• Wet contaminated areas thoroughly with a 10% bleach solution or EPA-approved disinfectant and let it sit for at least 10 minutes

• Wipe up using paper towels and dispose of everything in sealed bags

• Wear rubber or latex gloves throughout the process

• In enclosed or poorly ventilated spaces, wear an N95 or HEPA-filtered respirator

For outdoor and rural activities:

• Avoid areas with visible rodent activity, especially in cabins or shelters that have been closed for a season

• Air out enclosed spaces before entering and use a disinfectant before cleaning

• Store sleeping gear off the ground and in sealed bags when camping

Latest Research: Progress on Multiple Fronts

The 2026 MV Hondius outbreak triggered a wave of urgent scientific activity. Several promising developments are now underway.

Faster, more accurate diagnosis. Researchers at the University of Nebraska Medical Center developed and validated a diagnostic-grade PCR test specifically for the Andes virus in May 2026. This matters because standard U.S. tests, designed to detect the Sin Nombre Virus, frequently miss the genetically distinct Andes strain. That gap has cost lives.

Vaccine development is accelerating. Two separate tracks are showing early promise:

• USAMRIID has completed Phase 1 trials for an Andes virus DNA vaccine, showing the generation of neutralizing antibodies in humans

• Moderna, in collaboration with Korea University, is pursuing a preclinical mRNA-based approach, following the same platform used for COVID-19 vaccines

• The University of Bath in the UK is developing a thermally stable mRNA vaccine for the Hantaan strain using a novel technology called ensilication, which could make the vaccine easier to store and distribute globally

Experimental treatment under evaluation. During the MV Hondius outbreak, Japan supplied the UK with favipiravir, an antiviral that shows activity against hantavirus in animal models. It was used on a compassionate basis in humans, though large-scale clinical trial data is still pending. Treatment currently remains supportive: mechanical ventilation and, in the most severe cases, ECMO (extracorporeal membrane oxygenation).

Understanding who is at greatest risk. A 2026 systematic review identified key risk factors for fatal outcomes in New World hantavirus cases. These include being over 18, living in a rural area, elevated creatinine levels, increased hematocrit, and visible infiltrates on a chest X-ray. This information helps clinicians escalate care faster for the most vulnerable patients.

What You Should Do Now

Hantavirus is serious but preventable. The biggest risks come from complacency: cleaning out a dusty shed without protection, camping in a rodent-infested cabin, or dismissing early symptoms as a common cold.

Take rodent control seriously at home and at work. Use proper protective gear when cleaning enclosed spaces. And if you live in or travel to high-risk areas, especially rural parts of the American Southwest or South America, stay informed through the CDC and WHO.

Research is moving faster than ever before. The first hantavirus vaccine may not be far off. Until then, awareness and prevention remain the most effective tools available.

This article is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare professional for guidance specific to your situation.