As global health officials scramble to contain a deadly outbreak of hantavirus aboard a luxury cruise ship, the rare but potentially fatal disease has once again thrust itself into the spotlight. The recent cluster of cases—including three deaths—on the MV Hondius off the coast of Cape Verde has reignited concerns about this rodent-borne illness, which remains one of the most serious zoonotic threats in the world. While hantavirus infections are uncommon, their severity demands urgent attention, especially as travel and climate shifts may expand the virus’s reach. Here’s what you need to know about hantavirus: what it is, how it spreads, its devastating symptoms, and the diseases it causes.
Hantaviruses are a family of viruses primarily transmitted by rodents, including mice, rats, and voles. Unlike many infectious diseases, hantaviruses do not spread directly between people—except in rare cases involving the Andes virus, which has been documented to transmit through human-to-human contact. The most common hantavirus in the Americas, the Sin Nombre virus, is carried by deer mice and causes hantavirus pulmonary syndrome (HPS), a severe respiratory illness with a mortality rate as high as 38% once symptoms progress to lung failure. In Europe and Asia, hantaviruses like the Seoul virus and Hantaan virus trigger hemorrhagic fever with renal syndrome (HFRS), a disease that attacks the kidneys and can also be fatal.
The recent outbreak on the MV Hondius—a Dutch-flagged ship operating in the South Atlantic—has raised alarming questions about how such a disease could emerge in a controlled environment like a cruise liner. According to the World Health Organization (WHO), the ship carried 147 passengers and crew when it docked in Cape Verde after reporting two laboratory-confirmed cases and five suspected cases of hantavirus. The three deaths linked to the outbreak have prompted the WHO and cruise operator Oceanwide Expeditions to launch an investigation, though the exact source of the infection remains under scrutiny. Experts speculate that rodent contamination—possibly through food storage areas or ventilation systems—may have played a role, though no definitive link has been confirmed.
What is hantavirus, and how does it spread?
Hantaviruses are not new. They have circulated in rodent populations for decades, but human infections typically occur when people inhale airborne particles contaminated with rodent urine, feces, or saliva. The virus can also enter the body through cuts or abrasions after contact with infected materials. Unlike many viruses, hantaviruses do not survive long outside their host, which is why outbreaks are often tied to specific environments where rodents are present—such as farms, rural cabins, or, in this case, a cruise ship.
According to the U.S. Centers for Disease Control and Prevention (CDC), the primary mode of transmission is through disturbing rodent nests or droppings, which can aerosolize the virus. This is particularly risky in poorly ventilated spaces, where contaminated dust or droplets may linger. The CDC emphasizes that pet rodents, including hamsters and rats, are not recommended for households with young children, pregnant women, or immunocompromised individuals due to the heightened risk of exposure.
One critical misconception is that hantavirus spreads easily between people. While the Andes virus in South America has demonstrated limited human-to-human transmission, most hantaviruses—including those causing HPS—do not. This means that close contact with an infected person is unlikely to lead to infection, though healthcare workers may take precautions when caring for severe cases.
Symptoms of hantavirus: A two-phase illness
The progression of hantavirus infection is often divided into two distinct phases, each with its own set of symptoms. Early signs, which appear 1 to 8 weeks after exposure, are nonspecific and can mimic other illnesses like the flu. These include:
- Fatigue
- Fever
- Muscle aches, particularly in large muscle groups (thighs, hips, back)
- Headaches
- Dizziness or chills
- Abdominal pain, nausea, vomiting, or diarrhea (reported in about half of cases)
If untreated, the disease progresses to its second phase, characterized by severe respiratory distress. Four to ten days after the initial symptoms, patients may develop:
- Coughing and shortness of breath
- Chest tightness
- Lung fluid accumulation (pulmonary edema), which can be fatal
In cases of HFRS, the later phase involves kidney failure, low blood pressure, and internal bleeding. The severity of symptoms varies widely, but early diagnosis and supportive care—such as mechanical ventilation for HPS—are critical to survival. Unfortunately, there is no vaccine or specific antiviral treatment for hantavirus, making prevention the only reliable defense.
The two deadly diseases caused by hantaviruses
Hantaviruses are classified into two major syndromes, depending on the region and the specific virus involved:
1. Hantavirus Pulmonary Syndrome (HPS)
HPS is the primary concern in the Americas, where it is caused by viruses like Sin Nombre, New York, and Bayou. The deer mouse (Peromyscus maniculatus) is the most common carrier in the U.S., particularly in rural and semi-rural areas. Symptoms of HPS begin with flu-like illness and rapidly worsen into respiratory failure as the lungs fill with fluid. The CDC reports that approximately 38% of HPS patients who develop respiratory symptoms die, though early intervention can improve outcomes. Since 1993, the U.S. Has seen an average of 20 to 30 cases per year, with higher rates in the Southwest, and Midwest.
Key risk factors for HPS include:
- Cleaning rodent-infested areas without proper protection
- Living or working in areas with high rodent populations (e.g., farms, campsites)
- Disturbing rodent nests or droppings
2. Hemorrhagic Fever with Renal Syndrome (HFRS)
HFRS is more common in Europe and Asia, where viruses like Hantaan, Dobrava-Belgrade, and Seoul circulate. The Seoul virus, carried by brown rats (Rattus norvegicus), is found globally, including in urban areas where rats are prevalent. HFRS progresses through five phases:
- Fever phase: Sudden onset of high fever, chills, and back/abdominal pain (lasts 3–7 days).
- Hypotensive phase: Low blood pressure, shock, and kidney damage (days 4–6).
- Oliguric phase: Severe kidney failure with minimal urine output (days 6–12).
- Diuretic phase: Increased urine production as kidneys recover (days 13–15).
- Convalescence: Gradual recovery over weeks.
The mortality rate for HFRS ranges from 1% to 15%, depending on the virus and access to medical care. The Seoul virus, for example, tends to cause milder cases compared to Hantaan, which can be fatal in up to 12% of infections.
Why the cruise ship outbreak is raising concerns
The MV Hondius incident is unusual not only because of its location—a cruise ship—but also because it highlights how quickly hantavirus can spread in confined spaces. While the exact chain of transmission remains under investigation, experts point to several potential scenarios:
- Rodent contamination: Stowaways or rodents in food storage areas could have introduced the virus.
- Airborne exposure: Disturbing nests or droppings in poorly ventilated areas (e.g., cabins, galleys) may have aerosolized the virus.
- Human-to-human transmission (unlikely but possible): If the Andes virus strain were involved, close contact among passengers could have played a role.
The WHO has emphasized that the outbreak is still under investigation, and no definitive cause has been confirmed. However, the agency has issued guidance for cruise lines to enhance rodent control measures, including:
- Regular inspections of food storage and ventilation systems
- Sealing potential entry points for rodents
- Training crew on hantavirus symptoms and reporting protocols
This is not the first time hantavirus has made headlines in recent years. In 2025, the death of actress Betsy Arakawa from HPS in the U.S. Drew global attention to the disease, underscoring its unpredictability. Climate change may also be expanding the habitats of rodent carriers, increasing the risk of human exposure in new regions.
Prevention: Protecting yourself and your community
Given that there is no cure or vaccine for hantavirus, prevention relies on minimizing contact with rodents and their waste. The CDC and WHO recommend the following steps:
- Seal entry points: Inspect homes, cabins, and ships for gaps, holes, or cracks that rodents could use to enter.
- Eliminate food sources: Store food—especially pet food—in airtight containers and avoid leaving trash exposed.
- Clean safely: When cleaning areas suspected of rodent activity, use gloves and a damp cloth to avoid stirring up dust. Disinfect with a bleach solution (1 part bleach to 10 parts water).
- Ventilate: Open windows and use fans to reduce airborne particles when cleaning.
- Avoid pet rodents: The CDC advises against keeping pet rodents in households with young children, pregnant women, or immunocompromised individuals.
For travelers, especially those visiting rural or remote areas, additional precautions include:
- Avoiding sleeping on the ground or in tents that may be near rodent nests.
- Using insect repellent and wearing long sleeves/pants in wooded or grassy areas.
- Reporting any unusual rodent activity to local health authorities.
What’s next for the cruise ship outbreak?
The WHO and Oceanwide Expeditions are expected to release further details on the MV Hondius investigation in the coming days, including whether additional cases are confirmed and how the ship’s crew and passengers were exposed. In the meantime, health officials are urging cruise lines to prioritize rodent control and passenger education. For travelers, the outbreak serves as a reminder that even in controlled environments, zoonotic diseases like hantavirus remain a risk.
If you suspect hantavirus exposure, seek medical attention immediately. Early symptoms can be treated supportively, but delays increase the risk of severe complications. For the latest updates, monitor official sources such as the WHO and CDC.
Have you or someone you know experienced symptoms after potential rodent exposure? Share your concerns in the comments below—or help raise awareness by sharing this article to ensure others stay informed.