Emerging Andes virus cases—capable of person-to-person transmission—are prompting US clinical labs to reassess hantavirus protocols and consider travel and epidemiologic exposures beyond rodent contact.

By Alyx Arnett

For most laboratorians in the United States, hantavirus has long been synonymous with Sin Nombre virus, a pathogen transmitted through contact with the urine or feces of infected rodents. Recent Andes virus cases, however, are prompting laboratories to revisit how they think about hantavirus exposure and transmission.

Unlike Sin Nombre virus, Andes virus can also spread through respiratory secretions from an infected person. According to Elizabeth A. Talbot, MD, deputy state epidemiologist for New Hampshire, while all hantaviruses can be acquired through rodent-contaminated environments, “Andes has a unique additional ability to spread through an infected person’s respiratory secretions.”

That distinction is drawing closer attention from clinical and public health laboratories because Andes virus is the only hantavirus known to spread person to person under certain close-contact circumstances.

“The recent attention on Andes virus is shifting the hantavirus discussion in a meaningful way,” says Konstanze Stiba, PhD, product manager for infection diagnostics at Revvity’s Euroimmun. “For laboratories, this broadens the scope of awareness beyond rodent exposure alone. Clinicians and laboratorians may now also need to factor in recent travel to South America, contact with outbreak-associated travelers, or epidemiologic connections between cases.”

The Diagnostic Pathway for a Rare Pathogen

Hantavirus infections are often suspected when clinicians identify severe respiratory illness alongside a compatible travel or exposure history. According to Stiba, patients typically present with findings like fever, myalgias, thrombocytopenia, and leukocytosis, which can resemble more common viral illnesses such as influenza or COVID-19.

Hospital and health system laboratories are typically involved early in the process through specimen collection, preliminary evaluation, and ruling out more common infectious causes. Confirmatory hantavirus testing is generally referred to state public health laboratories, the CDC, or specialized reference laboratories.

Two primary methods are used for diagnosis: PCR to detect the virus itself and serology to detect antibodies. Because the incubation period can be as long as 42 days, antibodies are often present by the time symptoms appear. “The IgM is usually positive by the time a patient is symptomatic,” Talbot notes.

That timing makes serology especially useful in routine hantavirus diagnosis, since most patients seek care after symptoms begin. PCR testing can still play an important role, particularly early in infection, but Danielle A. Cervasio, PhD, associate scientific affairs liaison at Revvity’s Euroimmun, notes that the viremic phase is often brief and difficult to capture.

A Focus on Preparedness, Not Volume

Despite the recent attention, hantavirus remains rare in the US, with fewer than 900 cases reported between 1993 and 2023, according to Talbot. As a result, experts do not expect hantavirus testing to become common in most clinical laboratories. Instead, the greater shift may involve laboratory awareness and preparedness.

“What may change more substantially is laboratory preparedness and awareness rather than overall testing volume,” Stiba says.

Most hospital laboratories do not perform definitive hantavirus testing onsite. But Stiba says they still play an important role in identifying possible cases, following appropriate specimen handling precautions, coordinating send-out testing, and communicating with infection prevention and public health officials.

Stiba says recent infectious disease outbreaks have reinforced the importance of preparing before rare pathogens appear. Laboratories that invest in biosafety practices, adaptable diagnostic systems, workforce training, and strong public health partnerships may be better equipped to respond when unusual cases arise.

Navigating Testing Challenges

Less commonly encountered hantavirus strains such as Andes virus can create additional challenges for laboratories, particularly around test availability and interpretation. Many commercial serologic assays were developed with other hantavirus strains in mind. While these tests can often detect infection through cross-reactivity, they may not identify the specific virus involved.

“Laboratories may detect ‘hantavirus-positive’ serology without being able to immediately distinguish which hantavirus is involved,” Stiba says. “In an outbreak setting, epidemiologic context becomes essential.”

This cross-reactivity can complicate diagnosis. Hantaviruses share antigenic similarities, which is useful for screening but can make it difficult to differentiate between Sin Nombre and Andes virus.

According to Stiba and Cervasio, while the basic laboratory methods are similar across species, the antigens used to detect them can differ significantly. For this reason, Stiba says combined molecular and serologic testing can help improve interpretation in suspected acute cases and support strain characterization.

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