What Is Hantavirus? Symptoms, Causes & Treatment

Breaking: Active Outbreak

As of May 10, 2026, the CDC has raised its travel response to Level 3 following a confirmed hantavirus cluster aboard the cruise ship MV Hondius. Eight cases have been reported across multiple countries, including three deaths. 

Read the CDC's live situation summary →

If you've seen the word "hantavirus" trending on social media this week, you're probably wondering whether you should be worried — and what this virus actually is. The short answer: hantavirus is a serious illness, but the current outbreak is contained and the global risk to the public remains low. The longer answer is below.

Here's everything you need to know, grounded in the latest guidance from the WHO, the CDC, and public health authorities tracking the 2026 cruise ship cluster.

What Is Hantavirus?

Hantavirus is a family of RNA viruses that primarily infects rodents. There are more than 50 known strains, and most of them cause no visible symptoms in their animal hosts. The problem arises when those viruses make the jump to humans — often through contact with rodent urine, droppings, or saliva.

In humans, hantavirus can trigger two distinct and potentially fatal syndromes. The first, and most common in North America, is Hantavirus Pulmonary Syndrome (HPS) — a severe lung disease. The second, more common in Europe and Asia, is Hemorrhagic Fever with Renal Syndrome (HFRS), which attacks the kidneys.

The strain currently making international headlines in May 2026 is the Andes virus, a South American strain first identified in Argentina in the late 1990s. It has the unique — and alarming — distinction of being the only known hantavirus strain capable of spreading from person to person, though even this is typically limited to close, prolonged contact.

How Does Hantavirus Spread?

The most common route of infection is inhalation. When infected rodents shed the virus through their droppings, urine, or saliva, the particles can become airborne, particularly when disturbed — for example, by sweeping a barn floor, cleaning an old cabin, or handling rodent nests. Breathing in these microscopic particles is how most people get infected.

You can also contract hantavirus by:

Hantavirus is not transmitted through casual contact, coughing, or standard social interactions. It cannot be contracted from touching surfaces that infected people have touched. The Andes virus exception for person-to-person spread requires extended, intimate contact — which is why the cruise ship environment, with passengers sharing confined spaces, proved to be a risk factor in the current outbreak.

Symptoms: What Does Hantavirus Feel Like?

One of the most dangerous aspects of hantavirus is how innocent it looks in its early stages. The initial symptoms closely mirror the flu, making it easy to dismiss until the disease suddenly and rapidly escalates.

If patients survive the cardiopulmonary phase — which can be brutal and fast — recovery typically begins within days, and most survivors experience few long-term effects. The danger window is narrow but extremely severe.

"Symptoms may develop rapidly. Early medical care is critical."

— U.S. Centers for Disease Control and Prevention, May 2026

Causes: Where Does Hantavirus Come From?

Every hantavirus strain is linked to a specific rodent host. In North America, the deer mouse (Peromyscus maniculatus) is the primary carrier of the Sin Nombre virus, which caused the first recognized HPS outbreak in the U.S. Southwest in 1993. In South America, the long-tailed pygmy rice rat carries the Andes virus.

The 2026 outbreak appears to trace back to a Dutch couple who went on a birdwatching excursion at an Argentine landfill site before boarding the MV Hondius in Ushuaia on April 1. According to Argentine health authorities, the index case had completed a four-month road trip across Chile, Uruguay, and Argentina — regions where the Andes virus is endemic in local rodent populations.

High-risk environments for exposure include:

Treatment for Hantavirus

This is the part that makes clinicians nervous: as of 2026, there is no specific antiviral treatment approved for hantavirus infection. Both the WHO and CDC confirm that management is entirely supportive, meaning doctors treat the symptoms and keep the patient alive while the immune system fights the virus.

What Supportive Care Looks Like

Patients with severe HPS require intensive care hospitalization. Treatment typically involves:

Current Research

Several research programs are exploring antivirals and vaccines for hantavirus. The drug ribavirin has shown some promise in laboratory and early clinical settings for HFRS, though evidence for HPS remains limited. Monoclonal antibody therapies targeting the Andes virus are also in preclinical development. As of 2026, no vaccine has been approved for use outside of South Korea, where a formalin-inactivated vaccine against Hantaan virus (a different strain) is licensed for limited use.

The current outbreak on the MV Hondius may accelerate international research cooperation, as European, South African, and American health authorities now have real-world case data to study — particularly around person-to-person Andes virus transmission.

How Serious Is the Current 2026 Outbreak?

The honest answer is: serious for those directly affected, but low risk for the general public. Here's the timeline of what happened:

• April 1, 2026
  MV Hondius departs Ushuaia, Argentina, with 147 passengers and crew from 23 countries.
• April 6–28
  Illness onset among first cluster of patients. First passenger dies on April 11; his wife dies on April 26 in Johannesburg after disembarking in Saint Helena.
• May 2
  WHO receives official notification. Laboratory confirms hantavirus. A third passenger dies on board.
• May 6
  WHO and CDC confirm the Andes virus as the causative strain. CDC raises travel response to Level 3.
• May 8–9
  Eight confirmed and suspected cases across six countries. Ship transits to Tenerife.
• May 10
  MV Hondius docks in Tenerife. Evacuations begin. WHO Director-General personally oversees arrival. None of the 17 American passengers on board have tested positive.

WHO has consistently assessed the global public risk as low. The CDC echoes this: "At this time, the risk to the American public is extremely low." The Andes virus, while capable of person-to-person transmission, requires close and prolonged contact — it is not airborne in the way influenza or SARS-CoV-2 are. Experts across the board are clear: this is not another COVID-19.

"Historically with the Andes virus, it's spread between people in close proximity, so the risk of this transmitting more widely is pretty low."

— Virologist quoted by TODAY.com, May 2026

How to Protect Yourself From Hantavirus

Whether you're traveling to South America, spending time in rural areas, or simply want to reduce your risk, the following precautions are evidence-based and recommended by global health authorities:

The WHO's official guidance on the current outbreak is clear: "Ventilate first. Do not dry sweep or vacuum. Wet contaminated material with disinfectant, wear gloves, and follow local public health guidance." That last directive — wear gloves — is something we'll cover in depth in our companion guide on glove selection for hantavirus protection.

The Bottom Line

Hantavirus is a rare but genuinely dangerous pathogen. It carries a high case fatality rate, has no approved antiviral treatment, and can escalate from flu-like symptoms to life-threatening respiratory failure within days. The Andes strain, currently circulating in the MV Hondius outbreak, adds the complication of limited person-to-person transmission.

But context matters. Fewer than ten cases have emerged from this outbreak, which originated in one of the world's most remote wildlife-rich travel corridors. Global health authorities are coordinating effectively, the ship has reached safety, and the returning passengers are being monitored closely. The risk to people not directly involved in this situation or exposed to rodent habitats in South America is genuinely very low.

The best thing most people can do is stay informed, avoid complacency around rodent exposure, and know how to protect themselves — starting with basic protective equipment.