Hantavirus comes home: what American employers need to know

They boarded an expedition cruise ship in Argentina. They came home, without symptoms, to Arizona, California, Georgia, Texas and Virginia. Then, on Sunday, 17 more Americans disembarked in protective gear from the MV Hondius at the port of Tenerife in Spain's Canary Islands and boarded a charter flight to Omaha, Nebraska — headed for the country's only federally funded quarantine unit, at the University of Nebraska Medical Center.

"For the passengers getting off the ship, I'd say, 'Welcome to Nebraska,'" said Dr. Ali Khan, dean of the College of Public Health at the university. "You are coming to the premier facility in the United States, if not the world, to take care of you."

The disease that made that welcome necessary is hantavirus — specifically the Andes strain, which has killed three people and infected at least eight aboard the Dutch expedition ship since it departed Ushuaia, Argentina, on April 1. The CDC has classified its response as a Level 3 emergency. Investigations are continuing across 22 countries. None of the American passengers has tested positive.

The risk to the broader public, health authorities are emphatic, is low. "We do know that you can get small clusters of disease, but in 30 years we've never seen any large outbreaks," Khan told NPR. "This is unlikely to become a pandemic."

For American employers and HR professionals, however, the situation asks a specific and practical question: when a deadly, slow-incubating infectious disease starts dispersing into the American workforce — across multiple states, with no symptoms and no test that can confirm exposure before illness — what exactly is your organization supposed to do?

What the Andes strain is, and why it is unusual

Hantavirus is not unfamiliar on American soil. From 1993 through 2023, the CDC recorded 890 laboratory-confirmed cases in the United States, caused mainly by the Sin Nombre virus, which spreads through contact with infected deer mice and is concentrated in the rural Southwest and Great Plains. It does not pass between people.

The Andes virus is different in one critical respect: it is the only hantavirus documented to transmit between humans. That transmission remains rare and demands prolonged, close physical contact with a symptomatic person — sharing a bed, intimate contact, or sustained proximity in caregiving. It is emphatically not airborne in the way influenza or Covid-19 are.

"This is a very different virus," Maria Van Kerkhove, WHO director for epidemic and pandemic preparedness and prevention, told a news briefing last week. The disease cannot spread through a shared elevator or an open-plan office.

The virus causes hantavirus pulmonary syndrome. It begins with flu-like symptoms — fever, fatigue, muscle aches — and can escalate rapidly to severe respiratory failure. The CDC estimates that roughly 38% of patients who develop serious respiratory symptoms will die. There is no vaccine and no specific antiviral treatment; early supportive care is the only intervention available, and the CDC notes that "patients with suspected HPS can deteriorate rapidly." The incubation period runs from four to 42 days, an unusually wide window with real implications for monitoring.

The employer's legal exposure

Under Section 5(a)(1) of the Occupational Safety and Health Act — the General Duty Clause — every covered employer in the United States must provide a workplace free from recognized hazards that are causing or are likely to cause death or serious physical harm. Hantavirus, for workers with occupational rodent exposure, is precisely such a hazard, and the CDC's HAN Health Advisory issued last week explicitly called on employers to be aware of the potential for imported cases.

For the vast majority of American office workers, the Andes strain presents no meaningful occupational risk. The virus is not here, it does not spread casually, and the 24 Americans now being monitored are all, as of this writing, asymptomatic.

But the General Duty Clause does not only apply when a hazard has materialized. OSHA has consistently held that employers are required to act on recognized hazards — and the current situation, with Americans returning from a high-profile outbreak and dispersing across multiple states, qualifies. The question is what "acting" looks like in practice.

For workers in industries with genuine rodent exposure — agriculture, construction, warehousing, pest control, rural property management — the answer is well-established: WorkSafeBC's exposure control framework, long adopted informally by American operators in affected regions, calls for professional rodent control, respiratory protection for workers cleaning potentially contaminated spaces, and wet-cleaning methods rather than dry sweeping. These are reasonable precautions, not heroic ones.

For most employers, the relevant obligations are more mundane but no less real. A workplace culture that actively discourages presenteeism — one in which workers feel safe staying home when unwell — is not merely an ethical preference; it is a public health mechanism. Research published in the Journal of Occupational and Environmental Medicine found that workplaces with strong infectious disease protocols shape employee behavior beyond the office itself, reducing the likelihood that symptomatic workers will move through public spaces.

The sick leave problem, restated

There is an aspect of the hantavirus story that receives almost no attention in the public health conversation, and it is the one that most directly concerns American HR professionals.

The United States remains one of the only wealthy nations with no federal mandate for paid sick leave. HRD America has reported on how this places the U.S. in company with Somalia and Angola when it comes to statutory protections. The Family and Medical Leave Act provides up to 12 weeks of unpaid job-protected leave — cold comfort for an hourly worker facing a 42-day monitoring window. A patchwork of state laws fills some of the gap, but coverage remains uneven and, in many states, non-existent.

Read more: Sick leave around the world: how does the US stack up?

The consequence is predictable. Workers who cannot afford to lose income will come to work symptomatic. They have done so through every outbreak in modern American history. Research examined by HRD America found that 40% of workers feel insecure taking sick time even when they are entitled to it, fearing judgment or retaliation. Hantavirus, with its flu-like early symptoms, is precisely the kind of disease that a worker might decide to "push through."

Read more: Why are so many workers hesitant to file sick leave?

Employers cannot solve the structural failure of American sick leave policy. But they can examine their own frameworks honestly. If a warehouse worker or field technician in their employ returned from Argentina, developed a fever and muscle aches three weeks later, and had no paid sick leave available — what would that worker do? The answer matters, both for that worker and for everyone they encounter.

Four things employers should act on now

Assess which of your workers have genuine exposure risk. The Andes strain is South American and requires close prolonged contact. The Sin Nombre strain is domestic and transmitted by rodents. Both are relevant, depending on your workforce. Employees in outdoor industries, agriculture, rural construction, or who travel to South America for work warrant a specific conversation, not a generic all-hands.

Review business travel protocols for South America. The first two confirmed cases on the Hondius likely contracted the virus during a months-long birdwatching expedition through Argentina, Chile and Uruguay before boarding the ship. Employees traveling to the region for fieldwork, natural resource projects, ecotourism or agricultural research should receive the CDC's current precautionary guidance: avoid rodent contact, use wet-cleaning methods in rural settings, and seek medical attention promptly if symptoms develop after travel.

Ensure managers know what to do — and what not to do. If a team member returns from South America and develops flu-like symptoms, managers need a clear protocol: refer to HR and occupational health, avoid asking employees to disclose specific diagnoses (which implicates ADA and HIPAA), and document the steps taken. Improvised responses are where legal exposure accumulates.

Use this moment to audit your leave and remote work policies. Not because hantavirus is coming to an American office, but because the next pathogen might be. An employee who would lose a week's pay by staying home sick is an employee with an incentive to come in. That incentive is a public health risk and a liability. The cost of addressing it proactively is much lower than the cost of addressing it after an outbreak.

Twenty-four Americans are currently being monitored for a disease that kills nearly four in ten people who develop its worst symptoms. All are asymptomatic. The response — federal quarantine units, CDC coordination teams, state health department notifications — is running as it should.

But the MV Hondius is also a kind of test. Not of whether American public health agencies can manage a rare, imported pathogen — they can — but of whether American workplaces have built the underlying culture, policies and flexibility to behave sensibly when infectious disease crosses the threshold. That test has no official score. Employers grade themselves.