What is Hantavirus? What are its Symptoms, Transmission Routes, and Treatment?

Hantavirus is a family of RNA viruses that can be transmitted to humans via rodents and can cause severe respiratory and renal failure. According to data from the World Health Organization (WHO) and the US Centers for Disease Control and Prevention (CDC), hantavirus infection affects an estimated 200,000+ people worldwide each year, and a significant portion of cases can result in death. An outbreak on the cruise ship MV Hondius sailing in the Atlantic Ocean in 2025 has once again heightened global awareness regarding this virus.

What is hantavirus?

According to the official definition by WHO, hantaviruses are zoonotic viruses belonging to the Hantaviridae family that naturally infect rodents and can occasionally be transmitted to humans. These viruses possess a single-stranded, negative-sense RNA structure consisting of three genomic segments: Small (S), Medium (M), and Large (L) segments. The virus primarily attacks microvascular endothelial cells, disrupting vascular permeability; this leads to organ damage in the kidneys during HFRS and in the lungs during HPS.

There are numerous distinct types of hantaviruses worldwide, and those most significant to human health include:

• Sin Nombre Virus (SNV): The primary agent causing HPS in the United States.
• Andes Virus (ANDV): Found in South America; it is the only hantavirus species where person-to-person transmission has been documented.
• Hantaan Virus: Causes HFRS in Asia; it is among the species with the highest mortality rates.
• Seoul Virus: A widespread global species that causes HFRS; it is seen in many countries, including the United States.
• Puumala Virus: Found in Europe, particularly Northern and Central Europe; it causes a relatively mild form of HFRS.
• Dobrava-Belgrade Virus: Prevalent in the Balkans; it can lead to severe clinical pictures of HFRS.

Two Main Conditions Caused by Hantavirus

Hantavirus infection manifests through two primary clinical syndromes across the globe. These two forms carry distinct differences regarding the organ systems they affect and their geographical distributions.

Hantavirus Pulmonary Syndrome (HPS)

According to CDC data, HPS is a severe respiratory disease seen predominantly in the Americas. First identified during an outbreak in 1993 in the Four Corners region of the US (the area where Arizona, Colorado, New Mexico, and Utah meet), this syndrome was initially called “Four Corners Disease” before being named the “Sin Nombre virus.” CDC statistics show that 890 confirmed HPS cases were recorded in the US between 1993 and 2023. The mortality rate of HPS once respiratory symptoms develop is approximately 38%.

Hemorrhagic Fever with Renal Syndrome (HFRS)

HFRS is a severe clinical picture prevalent in Europe and Asia that affects the kidneys and the vascular system. According to WHO data, between 60,000 and 100,000 HFRS cases are reported globally every year, with approximately half of these cases occurring in China. A total of 77,558 cases and 866 deaths recorded in China’s Shaanxi province between 2006 and 2012 clearly demonstrate the regional burden of the disease.

What are hantavirus symptoms?

The CDC states that hantavirus infection typically presents symptoms one to eight weeks following exposure. The clinical course follows a two-stage structure; since the disease can mimic ordinary flu symptoms in its initial stage, early diagnosis can be difficult.

Early Stage Symptoms (First Phase)

Early phase symptoms identified by the CDC and WHO include:

• High fever and chills
• Headache and dizziness
• Severe muscle aches, particularly concentrated in large muscle groups such as the thighs, hips, back, and shoulders
• Extreme fatigue and weakness
• Gastrointestinal symptoms such as nausea, vomiting, abdominal pain, and diarrhea

Late Stage Symptoms (For HPS)

According to the CDC’s clinical guidelines, late-stage symptoms specific to HPS emerge four to ten days after the onset of the first phase. In this critical phase:

• Severe coughing and shortness of breath develop
• A feeling of heaviness and tightness in the chest occurs as the lungs begin filling with fluid
• Rapid heart rate (tachycardia) and low blood pressure (hypotension) may be observed
• Acute respiratory failure can develop, posing a life-threatening danger

HFRS Symptoms

According to WHO clinical definitions, HFRS presents a severe picture characterized by vascular wall damage, increased vascular permeability, hypertension, hemorrhagic (bleeding) findings, and shock. The primary clinical features of this picture can be listed as follows:

• Sudden-onset high fever, chills, and intense headache
• Nosebleeds and bleeding gums; microscopic bleeding within internal organs
• A significant decrease in urine output (oliguria) or a complete cessation of urine (anuria)
• Acute kidney failure; dialysis support may be required in severe cases
• Fluctuations in blood pressure and circulatory disorders

How is hantavirus transmitted?

According to statements from the CDC and WHO, hantavirus is primarily transmitted to humans through the bodily secretions of infected rodents. Rodents carrying the virus often shed it into the environment via their urine, droppings, and saliva without displaying any signs of illness themselves.

Primary Transmission Routes

• Inhalation (Most Common): Inhaling micro-particles formed from the dried urine, droppings, or saliva of infected rodents. According to the CDC, this route constitutes the primary mechanism of transmission.
• Direct Contact: Touching surfaces contaminated with the virus and subsequently bringing the hands to the mouth, nose, or eyes without washing them.
• Bites or Scratches: Although extremely rare, a bite or scratch from an infected rodent can also lead to transmission.
• Contaminated Food Consumption: Eating foods contaminated with the secretions of rodents carrying the virus.

Does it spread from person to person?

According to current statements from WHO, hantavirus generally does not spread from person to person. However, the only known exception to this rule is the Andes virus, found exclusively in South America. WHO documents that the Andes virus can spread from person to person at a limited level within the same household or among close partners, particularly during the early stage of the disease.

Risk Factors and At-Risk Groups

According to data from the CDC and ECDC (European Centre for Disease Prevention and Control), the groups and situations carrying the highest risk for hantavirus infection are:

• Individuals living or working in rural or wooded areas: Farmers, foresters, camp attendants, and outdoor laborers are among the primary risk groups.
• Spaces exposed to rodent infestation: Warehouses, barns, summer houses, and basements that have been left unused for long periods and lack adequate ventilation carry a high risk.
• Seasonal activities: Caution should be exercised before spring cleaning, tent camping, and nature hikes.
• Travel: Risk increases for individuals traveling to endemic regions (especially Asia, the Balkans, and the Americas).

How is hantavirus diagnosed?

According to the CDC, a hantavirus diagnosis is confirmed through a combination of clinical evaluation and laboratory testing. The fact that symptoms overlap with many other viral infections is the primary factor complicating the diagnostic process.

The primary methods used in the diagnostic process are:

• Serological Tests: The ELISA method, used to detect IgM and IgG antibodies in the blood, is the most common first-step diagnostic method.
• PCR (Polymerase Chain Reaction): Enables the detection of the virus’s genetic material (RNA) in the blood; it is extremely valuable, especially during the early stage.
• Complete Blood Count: Typical findings such as leukocytosis, thrombocytopenia, and hemoconcentration (thickening of the blood) can point toward HFRS.
• Kidney Function Tests: Elevated BUN (blood urea nitrogen) and creatinine are frequently detected in HFRS.
• Lung Imaging: Chest X-rays or computed tomography (CT) are utilized to evaluate lung involvement when HPS is suspected.

The CDC emphasizes that a definitive diagnosis must always be based on laboratory confirmation (antibody or PCR testing). Because the clinical picture can deteriorate rapidly in suspected cases, the patient must be kept under close observation.

Hantavirus Treatment

Both the CDC and WHO explicitly state that there is no approved, specific antiviral treatment for hantavirus infection yet. Therefore, treatment relies entirely on supportive approaches, and early intervention is known to significantly increase the probability of survival.

Supportive Treatment Approaches

• Intensive Care Monitoring: In HPS or severe HFRS cases, pulse, blood pressure, respiration, and kidney functions are continuously monitored.
• Respiratory Support: According to the CDC, intubation and mechanical ventilation may be required if the lungs fill with fluid in HPS.
• Fluid Balance Management: Meticulous maintenance of fluid and electrolyte balance is of critical importance, especially in HFRS.
• Dialysis Support: Renal replacement therapy can be applied in HFRS cases that develop kidney failure.
• Symptom Control: General support is provided using antipyretics, antiemetics, and analgesics.

WHO emphasizes that early supportive medical care in treatment is life-saving, and close monitoring of respiratory function and the overall clinical picture improves outcomes. Ribavirin and various monoclonal antibody treatments, which are currently in the research phase, are being evaluated in clinical trials; however, these agents have not yet been included in standard treatment protocols.

Ways to Prevent Hantavirus

Stating that there is no approved vaccine or prophylactic drug for hantavirus, the CDC explains that the fundamental way to protect oneself is to prevent contact with rodents.

Precautions in Home and Living Spaces

• Seal all cracks and holes in the building. It should be remembered that mice can enter through openings wider than 6 mm.
• Store food in tightly covered, rodent-proof containers.
• Keep garbage inside durable cans with tight-fitting lids.
• Use an N95 respirator and nitrile gloves when entering spaces that have been unused for long periods (warehouses, barns, basements).

Safe Methods for Cleaning Rodent Droppings

According to the official cleaning protocol of the CDC:

• Thoroughly ventilate the area first (for at least 30 minutes).
• Spray household bleach or a commercial disinfectant directly onto the droppings or urine.
• Wait for at least 5 minutes before wiping it up with a paper towel.
• Dispose of the paper towels and materials by placing them in a sealed plastic bag.
• Never use a broom or a vacuum cleaner; these tools mix the virus into the air.

Global Epidemiology: Hantavirus Around the World

According to current data found in scientific literature and WHO reports, hantavirus continues to be an important public health issue on a global scale:

• Annual Global Burden: More than 200,000 people contract a hantavirus infection globally every year (Frontiers in Microbiology, 2023).
• HFRS Burden: Between 60,000 and 100,000 HFRS cases are reported annually; approximately half of these cases are observed in China (CNN/WHO, 2024).
• US Data: A total of 890 confirmed HPS cases were reported between 1993 and 2023, with cases predominantly concentrated in western states (CDC, 2023).
• HPS Mortality: The death rate is approximately 38% in patients who develop respiratory symptoms (CDC).
• HFRS Mortality: Varies between 1% and 12% depending on the virus species and the medical support received.
• Recent Outbreaks: 6 cases were reported in the outbreak on the vessel MV Hondius sailing in the Atlantic Ocean in 2025, 3 of which resulted in death (WHO, 2025).

When should a doctor be consulted?

The California Department of Public Health (CDPH) and the CDC recommend seeking immediate medical attention in the presence of the following symptoms:

• Fever, shortness of breath, or muscle pain presenting alongside a history of rodent contact
• Rapidly worsening breathing difficulties
• A sudden decrease or complete cessation in urine output
• Unexplained signs of bleeding (nosebleeds, bleeding gums, blood in the urine, etc.)
• Severe hypotension or changes in consciousness

A history of rodent contact or presence in a risky environment within the past two to four weeks must absolutely be stated when consulting a doctor. This information is vital for an accurate diagnosis and early intervention.