Hantavirus for the Dermatologist

1. Why Dermatologists Should Be Aware of Hantavirus Right Now

In April 2026, an outbreak of Andes virus, a severe strain of hantavirus, was linked to the M/V Hondius cruise ship departing from Ushuaia, Argentina. As of May 12, 2026, eleven cases and three deaths have been reported, with a case fatality ratio of 27%.^1,2 All six laboratory-confirmed cases were identified as Andes virus by PCR or sequencing. The World Health Organization (WHO) considers the global public health risk to be low. However, it has upgraded the risk on the ship to moderate, given close living quarters and documented person-to-person transmission on board.¹

The first patient is believed to have acquired the infection through rodent exposure before boarding, following three months of travel in Argentina, Chile, and Uruguay that included birdwatching. Subsequent cases appear to have resulted from person-to-person transmission on the ship.¹

While hantavirus is remains rare, dermatologists could be among the first to see patients with hantavirus infection because skin findings (petechial eruption, particularly axillary) can appear early in the illness, sometimes preceding other more serious signs and symptoms.³ However, the cutaneous findings may closely resemble other dermatologic conditions, leading to diagnostic delay (see below).

2. What is Hantavirus

Hantaviruses are enveloped RNA viruses of the Bunyaviridae family. They are found worldwide and are carried by specific rodent species (mice, rats, and voles,) in each endemic geographic region (see Table 1 below).^4,5 Transmission follows two seasonal peaks: a smaller one in spring and a larger one in fall, linked to increased human-rodent contact during farming seasons and to rodents moving indoors in colder months.⁶ Hantaviruses cause two distinct clinical syndromes depending on the infecting strain and geographic region:³

• Hantavirus Cardiopulmonary Syndrome (HCPS) is found in the Americas and is caused by Andes virus and Sin Nombre virus, among others. It primarily affects the lungs and heart. Andes virus has a case fatality rate of approximately 21 to 36%. It is the only hantavirus strain capable of spreading from person to person, typically through close and prolonged contact with infected individuals.

• Hemorrhagic Fever with Renal Syndrome (HFRS) is found in Europe and Asia and is caused by Hantaan, Dobrava, and Puumala viruses. Additionally, HFRS may be caused by Seoul virus, which has a global distribution including the U.S. It primarily affects the kidneys and blood vessels. Fatality rates differ by strain: less than 0.5% for Puumala and up to 15% for Dobrava.⁷

3. Who is at Risk

Hantavirus is transmitted mainly through inhalation of particles from the urine, fecal droppings, or saliva of infected rodents. The incubation period ranges from 1 to 6 weeks, and occasionally up to 8 weeks. As such, patients may present to a dermatologist weeks after the relevant exposure and not connect their symptoms to a rodent encounter or recent travel.^1,3 Common exposures include:^3,6

• Cleaning barns, cabins, storage spaces, or unused buildings

• Farming, forestry, or agricultural work

• Camping or outdoor recreational activities in endemic areas

• Ecotourism, such as birdwatching in rural South America, Europe, or Asia

In 2025, eight countries in the Americas reported 229 cases of hantavirus infection with 59 deaths.¹ The median age for HCPS is 34 years, and 70–80% of cases occur in men.³ Most cases occur in rural settings, though Seoul virus, which causes a milder form of HFRS, is found in urban areas worldwide.³

For Andes virus specifically, close contact with an infected person is also a risk factor, particularly for household members, sexual partners, and healthcare workers with unprotected exposure. Contacts of confirmed Andes virus cases should self-monitor for symptoms for 42 days after last exposure.¹

Cutaneous Manifestations

Skin findings in hantavirus are not caused by the virus directly infecting the skin. Rather, they result from thrombocytopenia and increased vascular permeability and leakage, two hallmarks of the infection.^3,6 These can appear early in the illness, before other more ominous signs and symptoms develop, and may be the first sign that prompts presentation to a dermatologist.

HCPS (Americas, Sin Nombre and Andes viruses)

Sin Nombre virus, the most common cause of HCPS in North America, is not typically associated with significant skin involvement.^6,8 Skin findings in HCPS have been more frequently reported with Andes virus. They include:^3,8

• Pinpoint non-blanching erythematous macules (petechiae) on the skin, particularly in the axillae and on the extremities

• Conjunctivitis

• Maculopapular eruptions are reported in rare cases

When present, the axillary location of petechiae may be a useful clinical clue as many common causes of petechiae do not preferentially affect this area. In a patient with fever and relevant exposure history, petechiae in this location should raise concern for hantavirus.

These skin findings are often accompanied by non-specific flu-like symptoms, including fever, fatigue, and myalgias, and appear during the early prodrome, typically one to seven days before respiratory symptoms develop. Recognizing the cutaneous manifestations during this window is important as the disease can rapidly progress to respiratory failure and cardiovascular collapse within hours.³

HFRS (Europe and Asia, Hantaan, Puumala, and Dobrava viruses)

HFRS produces a broader range of cutaneous findings, typically appearing within the first three to four days of illness:^3,6,9

• Facial flushing described as a sunburn-like redness of the face, neck, and chest. In rare cases, the facial erythema may resemble a lupus-like malar rash.⁹

• Petechiae on the skin and the mucosa, often appearing around day four

• Bruising (purpura and ecchymoses), more common in severe strains such as Hantaan and Dobrava

• Epistaxis, bleeding gums, hematemesis, or hematuria

4. Differential Diagnosis

Several conditions can mimic the cutaneous findings of hantavirus. These should be considered, but should not delay referral if hantavirus is suspected:^3,6,10

• Meningococcemia petechiae and purpura on the trunk and extremities that are rapidly progressive and may be retiform in morphology but typically associated with meningeal signs.

• Arboviral infections may have a similar constellation of symptoms.

• Dengue produces a morbilliform or petechial eruption and thrombocytopenia in the setting of high fever, flu-like symptoms, and bleeding diathesis. Facial flushing may also be seen in up to 50% of dengue patients.¹¹ Similarly, Zika virus may cause maculopapular or petechial eruptions with palatal petechiae, conjunctivitis, and systemic symptoms including fever and arthralgias.¹² Recent mosquito exposure in an endemic region, rather than rodent contact, is a key differentiator of arboviral infections, as their short incubation periods have average latencies of 3-14 days for dengue and Zika.

• Idiopathic thrombocytopenic purpura produces thrombocytopenia and petechiae without fever or systemic illness.

• Lupus can mimic the facial erythema seen in HFRS, particularly in the setting of elevated ANA and renal involvement.

• Vasculitis produces palpable purpura, typically with different systemic features.

• Other viral hemorrhagic fevers can produce similar cutaneous findings and should also be on the differential. These include Ebola, arenaviruses, such as those causing Lassa fever, and Crimean-Congo hemorrhagic fever. ⁶

Duration of symptoms, travel history, occupational and recreational activities, and the nature of exposure (rodent versus tick versus mosquito) are the most important distinguishing features.

5. When to Act

Send the patient to the emergency department or for direct hospital admission and notify your state, tribal, local, or territorial health department if a patient presents with skin findings consistent with hantavirus and any of the following:^3,13,14

• Fever (≥100.4° F/38° C) lasting more than 48 hours

• Severe myalgias, headache, chills, or acute gastrointestinal symptoms (nausea, vomiting, diarrhea, abdominal pain)

• Thrombocytopenia on CBC

• Abnormal renal functions, hematuria, or proteinuria

• Acute respiratory signs and symptoms (cough, shortness of breath, chest pain, or low oxygen saturation levels). These suggest the disease has progressed and are considered a medical emergency.

Also ask about:

• Residence in or travel to endemic areas of the Western United States.

• Recent travel to South America, rural Europe, or rural Asia

• Rodent exposure, such as cleaning a barn, cabin, or unused building

• Close contact with a known or suspected hantavirus case (Andes virus specifically)

• Symptom onset within the past 8 weeks

Infection control

Standard precautions (gloves and hand hygiene) are sufficient for suspected non-Andes hantavirus strains. However, for suspected Andes virus infections, contact and airborne precautions are recommended, including patient placement in an airborne infection isolation room and appropriate personal protective equipment for all healthcare workers providing care to the patient, including donning of gowns, gloves, eye protection, and N95 or higher-level respirators.^1,13,15 The current cruise ship outbreak included the ship's physician as a confirmed case, highlighting the importance of appropriate precautions.¹ Because HCPS can be fatal within 24 hours of the onset of respiratory symptoms, immediately notify the state, tribal, local, or territorial health department for all suspected hantavirus cases, as it is nationally reportable.^3,16

Diagnosis and Treatment

Diagnosis is made with a serum serology for IgM antibodies, which are usually present once symptoms appear. PCR can detect Andes virus up to two weeks before symptoms begin.² Dermatologists who have a high index of suspicion for hantavirus should send the patient to the emergency department or inpatient admission immediately, rather than initiating the workup themselves.

There is no approved antiviral treatment, so care is supportive. Ribavirin has shown some benefit in early HFRS in controlled trials, but is not effective for HCPS.^3,6 HCPS can be fatal within 24 hours of respiratory symptoms beginning, so early transfer to a facility with an ICU is essential, as interventions such as mechanical ventilation and ECMO capability may be lifesaving.^1,3