While hantavirus infections are rare, they can be associated with signs and symptoms that can lead a patient to the dermatologist’s office.

Cutaneous signs of hantavirus disease can be subtle and variable. 

“Hantavirus dermatology is fundamentally about pattern recognition rather than recognition of a specific rash,” said Giuseppe Gallo, MD, dermatologist and head of the Hair and Nail Outpatient Clinic at the University of Turin in Turin and researcher at the University of Bologna in Bologna, both in Italy. He was the first author of a recently published review article on cutaneous clues to hantavirus in the International Journal of Dermatology. “The visible manifestations reflect endothelial dysfunction, capillary leakage, thrombocytopenia, and platelet dysfunction, which explains the combination of flushing, petechiae, purpura, and mucosal bleeding,” he told Medscape Medical News.

Hantavirus has a 35% mortality rate according to the CDC. Its visibility was heightened in May when 13 cases of the Andes hantavirus, which spreads person-to-person, were reported on an international cruise ship, resulting in three deaths.

The kidneys and lungs are most affected. But skin manifestations “can appear before systemic complications are apparent,” resulting from “thrombocytopenia and vascular leak rather than from direct viral invasion of cutaneous tissue,” according to a brief report published in July in the Journal of the American Academy of Dermatology.

“In hantavirus cardiopulmonary syndrome, petechiae in the armpits and extremities and, rarely, a measles-like rash, have been reported with the Andes virus,” one of the report’s authors, Catherine Shen, medical student at the University of Pennsylvania in Philadelphia, told Medscape Medical News. “In hemorrhagic fever with renal syndrome, the findings are broader and more nonspecific, ranging from facial flushing to petechiae and even mucosal bleeding. Severe cases may also have purpura and ecchymoses,” she said.

Other signs can be less apparent but still telling within the proper context.

“Some of the most useful findings can actually be very subtle,” Gallo noted. “A few nonblanching macules in the axillae, a small cluster of palatal or gingival petechiae, mild facial flushing, or an unexplained subconjunctival hemorrhage may be more informative than a widespread rash when they occur in a febrile patient with thrombocytopenia and renal abnormalities.”

Adding further complexity, conditions that cause low platelets can present with similar cutaneous findings.

“Given the petechial eruption, other things can mimic [hantavirus],” Misha Rosenbach, MD, professor of dermatology, vice chair of education, and dermatology residency program director at the University of Pennsylvania, who is also a co-author of the Journal of the American Academy of Dermatology study, told Medscape Medical News.

“Some systemic reactions to medications, including cytokine storm or capillary leak,” could be the cause, he said. But he would consider other infections, including viral infections, such as dengue, which can have a similar rash and flushing, “or perhaps Zika, which can have some conjunctival injection along with a nonspecific morbilliform exanthem, and meningococcemia (with extensive petechiae).”

If a dermatologist suspects a patient may have hantavirus, a speedy reaction is key.

“The most important thing is to act quickly,” Shen said. “Take a thorough exposure history, including rodent contact and recent travel. If they see suggestive skin findings along with fever, myalgias, and any lung or kidney involvement, they should send the patient to the emergency department, contact infectious disease, and notify their local health department.”

Shen and Rosenbach pointed to the Emerging Diseases Resource Center of the American Academy of Dermatology Association (AAD) as an information source for dermatologists on hantavirus and other diseases.

According to Gallo, because there is no surefire skin sign for hantavirus, dermatologists should consider the full picture before making a determination.

“The key message for dermatologists,” he explained, “is to integrate morphology, systemic findings, laboratory abnormalities, and epidemiologic exposure, rather than relying on any single cutaneous sign.”

The authors declared having no relevant conflicts of interest. Rosenbach is the deputy chair of the AAD Emerging Disease Task Force but does not speak for the AAD.

Scott Harris has covered dermatology, rheumatology, and various other healthcare issues for more than a decade. He lives near Washington, DC.