global health – Doctor Rennie's Blog

If you’ve been following the news lately, you’ve probably seen hantavirus come up more than once. First it was the tragic death of Betsy Arakawa, the wife of actor Gene Hackman, in Santa Fe in February 2025. Then, just days ago, a cruise ship in the Atlantic became the center of an international health response involving the WHO, multiple governments, and passengers scattered across more than a dozen countries. So let’s talk about what hantavirus actually is, where the risk really comes from, and why one particular strain of this virus is changing how we think about transmission.

The Basics: A Rodent-Borne Illness

Hantavirus isn’t new. In the United States, it first grabbed serious attention in 1993 when healthy young adults in the Four Corners region of the American Southwest started dying of a mysterious respiratory illness. The culprit turned out to be a newly identified pathogen called Sin Nombre virus, spread by the deer mouse. That outbreak gave us a new diagnosis, hantavirus pulmonary syndrome, or HPS, and it launched decades of surveillance that continues today. According to the CDC, from 1993 through the end of 2023, the United States recorded 890 total cases. (1)

In the U.S. strain, the virus spreads from rodents to humans, not from person to person. People get infected when they breathe in aerosolized particles from the urine, feces, or saliva of infected animals. You don’t have to be bitten. You don’t have to handle a dead mouse. You can be sweeping out a shed or a cabin that sat empty all winter, and if infected rodents were living in there, you’re at risk the moment those dried particles become airborne. That’s how Betsy Arakawa most likely got sick. She was found deceased at her Santa Fe home in late February 2025, and the New Mexico Office of the Medical Investigator confirmed she died of hantavirus pulmonary syndrome. (2) Her husband, Gene Hackman, tested negative for the virus and died of heart disease. (2)

That case was a painful reminder. Hantavirus doesn’t make headlines often, but it doesn’t disappear either. New Mexico, Colorado, Arizona, and the broader Southwest are endemic areas. We see cases here. Our patients are at risk.

What the Disease Actually Looks Like

The illness comes in stages. The early phase looks frustratingly like the flu: fever, muscle aches, headache, fatigue, sometimes nausea, vomiting, and diarrhea. (3) That prodromal period can last several days. Then comes the part that kills people. The lungs fill with fluid. Patients develop acute respiratory distress syndrome. Blood pressure drops. The heart begins to fail. According to the WHO, the case fatality rate for hantavirus in the Americas reaches up to 50%. (4) The CDC and other sources put HPS mortality in the 30 to 40 percent range, depending on the strain. (5)

There’s no specific antiviral treatment that works for HPS. Ribavirin, a drug that works for some other viral hemorrhagic fevers, was tested and didn’t show benefit. (6) What we have is supportive care: ICU management, mechanical ventilation when respiratory failure sets in, careful fluid management to avoid making pulmonary edema worse. The CDC is clear that if you suspect HPS, get the patient to the ICU immediately, before you even have lab confirmation. (6) Without early aggressive care, most deaths occur within 24 to 48 hours of the cardiopulmonary phase onset. (6)

This is a disease where the clock moves fast once it turns.

Andes Virus: A Different Transmission Pattern

Here’s where things get more complicated. Most hantaviruses, including Sin Nombre, the strain we deal with in the U.S., don’t spread person to person. A patient with HPS from Sin Nombre is, for practical purposes, a dead end for transmission. Standard precautions are appropriate. That’s reassuring.

The Andes virus is different.

Andes virus is found in South America, primarily Argentina and Chile, and it’s carried mainly by the pygmy rice rat. (7) It’s the only hantavirus known to be capable of human-to-human transmission. (8) That capacity was first documented in a 1996 outbreak in southern Argentina, where 18 cases occurred in and around the towns of El Bolson, Bariloche, and Esquel. Notably, five of the patients were physicians, three of whom had directly cared for infected patients. (9) Two additional people who had contact with the patients but hadn’t visited the affected area also got sick, which strongly suggested person-to-person spread. That outbreak was significant. It forced a rethinking of how we approach Andes virus cases in clinical settings.

The transmission appears to happen through close, sustained contact with an infected person, likely through respiratory secretions. It isn’t casual. It’s not the kind of spread you get from being in the same room briefly. But it happens, and it happens enough that the WHO has classified hantaviruses as emerging priority pathogens with high potential to spark international public health emergencies. (10)

The Cruise Ship: A Real-Time Case Study

What’s unfolding right now on the MV Hondius, a Dutch-flagged expedition cruise ship, is the most visible illustration of Andes virus transmission risk in years.

The ship departed Ushuaia, Argentina on April 1, 2026, carrying 147 passengers and crew from 23 countries. The leading theory, according to Argentine health officials, is that a Dutch passenger couple contracted the Andes virus during a bird-watching trip in Ushuaia before boarding. Investigators believe the couple may have been exposed at a landfill during that outing, where infected rodents were present. (11) They had been traveling through Argentina, Chile, and Uruguay for months prior, passing through areas where Andes virus is endemic. (11)

Two people got sick. What makes this case significant is what happened next. By the time the WHO was notified on May 2, 2026, there were already multiple cases on board. As of today, May 8, 2026, there are nine suspected cases, six confirmed, and three deaths. (12) Patients are hospitalized in South Africa, Germany, the Netherlands, Switzerland, and Saint Helena. (12) The WHO has acknowledged that some cases among close contacts, including cabin-sharing passengers, may represent person-to-person transmission. (13) That distinction is critical. The initial infections almost certainly happened on land in South America. But the chain didn’t stop there.

A WHO epidemiologist noted at a briefing that “we do believe that there may be some human-to-human transmission happening among really close contacts, the husband and wife, people who’ve shared cabins.” (14) This is how Andes virus behaves when it gets into a confined space with sustained close contact. It doesn’t spread like a respiratory virus through casual exposure. But it can move.

The infected passengers came from multiple countries, disembarked at multiple ports before the outbreak was understood, and are now dispersed globally. Health authorities in the U.S. are monitoring former passengers in at least five states. (15) No Americans have shown symptoms as of this writing. The WHO’s assessment is that the global public health risk remains low, and WHO Director-General Tedros has stated that a large epidemic similar to COVID-19 is not anticipated. (15) That assessment reflects what we know about Andes virus: its person-to-person transmission is real but limited, and typically tied to close, prolonged contact rather than broad community spread.

The Argentina Context: Cases Are Rising

This is happening against a backdrop of a significant increase in hantavirus cases in South America. Argentina has recorded 101 confirmed hantavirus cases since June 2025, roughly double the 57 cases recorded in the same period the year before. (16) The mortality rate in Argentina’s current season has been approaching one-third of confirmed cases. (17) Chile has confirmed 39 cases through May 2026, already approaching its full-year 2025 total, with a fatality rate around 33%. (18)

Researchers and health officials point to climate change as a contributing factor. Warming temperatures and shifting rainfall patterns are expanding the habitat of infected rodents, allowing them to move into areas that weren’t previously endemic. (17) More rodents in more places means more exposure risk for more people.

This isn’t a fluke uptick. It’s a trend that warrants attention.

What This Means for Clinicians and Patients

In my practice here in Colorado, I haven’t had a hantavirus case this season. None yet. For patients in the American Southwest generally, the risk remains what it has been: don’t disturb rodent habitats without protection. If you’re cleaning out a garage, barn, cabin, or shed that may have had rodent activity, wet the area down with a disinfectant before sweeping. Don’t dry-sweep. Use gloves and, ideally, an N95 mask. Ventilate the space well before working in it. Those measures aren’t complicated, but they genuinely matter. (19)

For clinicians, the Andes virus situation is a reminder: take travel history seriously. Ask about travel. Every time. A patient presenting with a febrile illness and early respiratory symptoms who recently traveled to Argentina, Chile, or Uruguay deserves a careful look, and the incubation period for hantavirus is one to six weeks after exposure (3), so someone who bird-watched in Ushuaia in early April might not get sick until May. If a patient’s rapid flu test is negative, their COVID test is negative, and they look like they’re heading toward respiratory compromise, hantavirus should be in your differential.

If you’re dealing with a confirmed or suspected Andes virus case, talk to your infection control team. The evidence for person-to-person transmission isn’t theoretical. The 1996 Argentine outbreak included healthcare workers. The WHO and CDC guidance is clear that for Andes virus, standard precautions aren’t sufficient. Enhanced droplet and contact precautions are appropriate. (8)

There’s no vaccine. There’s no proven antiviral. Early ICU admission genuinely changes outcomes. A study using convalescent plasma from HPS survivors showed a reduction in mortality from 32% to 14% in one analysis. (20) That approach isn’t widely available, but it’s worth knowing exists.

The Bottom Line

Hantavirus isn’t new, but the Andes outbreak is a reminder that a rare disease still deserves a place in the differential.

For our patients here in Colorado, the message is straightforward: rodent exposure is the primary risk, and it’s avoidable with the right precautions. For those traveling to South America, know that the Andes virus is endemic there and that the current season has been severe. For clinicians seeing febrile illness with respiratory symptoms, keep a broad differential and ask about travel.

This week, if you’re clearing out a shed, barn, or cabin that sat closed over the winter, wet it down before you touch it. Wear a mask. Don’t dry-sweep.

Scott Rennie, D.O.

Sources:

CDC. Reported Cases of Hantavirus Disease. https://www.cdc.gov/hantavirus/data-research/cases/index.html

Source New Mexico. NMDOH reports first hantavirus death of 2025: Betsy Arakawa. March 7, 2025. https://sourcenm.com/briefs/nm-health-department-reports-first-hantavirus-death-of-2025-betsy-arakawa-gene-hackmans-wife/

Mayo Clinic. Hantavirus pulmonary syndrome: Symptoms and causes. https://www.mayoclinic.org/diseases-conditions/hantavirus-pulmonary-syndrome/symptoms-causes/syc-20351838

WHO. Hantavirus cluster linked to cruise ship travel, Multi-country. May 4, 2026. https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON599

StatPearls. Hantavirus Pulmonary Syndrome. NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK513243/

CDC. Clinician Brief: Hantavirus Pulmonary Syndrome. https://www.cdc.gov/hantavirus/hcp/clinical-overview/hps.html

NBC News. How hantavirus spreads: What to know about rare person-to-person transmission. May 6, 2026. https://www.nbcnews.com/health/health-news/hantavirus-outbreak-mv-hondius-cruise-ship-who-expert-explains-rcna343467

CDC. About Hantavirus. https://www.cdc.gov/hantavirus/about/index.html

Wells RM et al. An unusual hantavirus outbreak in southern Argentina: person-to-person transmission? Emerging Infectious Diseases. 1997;3(2). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2627608/

CNN. What doctors know about how the Andes hantavirus spreads. May 6, 2026. https://www.cnn.com/2026/05/06/health/andes-strain-hantavirus-explained

CNN. Hantavirus cruise ship heads for Spain’s Canary Islands. May 5, 2026. https://www.cnn.com/2026/05/05/africa/cruise-ship-hantavirus-who-intl

Wikipedia. MV Hondius hantavirus outbreak. Updated May 8, 2026. https://en.wikipedia.org/wiki/MV_Hondius_hantavirus_outbreak

WHO. WHO’s response to hantavirus cases linked to a cruise ship. May 7, 2026. https://www.who.int/news/item/07-05-2026-who-s-response-to-hantavirus-cases-linked-to-a-cruise-ship

NBC News. How hantavirus spreads. Op. cit.

Time. What Countries Are Linked to the Hantavirus Outbreak? May 7, 2026. https://time.com/article/2026/05/07/countries-hantavirus-hondius-cruise-ship/

Time. What Countries Are Linked to the Hantavirus Outbreak? Op. cit.

University of Nebraska Medical Center, The Transmission. Hantavirus is on the rise in Argentina. May 6, 2026. https://www.unmc.edu/healthsecurity/transmission/2026/05/06/hantavirus-is-on-the-rise-in-argentina-where-a-stricken-cruise-ship-began-its-journey/

UPI. Chile, Argentina report rise in deadly hantavirus cases. May 7, 2026. https://www.upi.com/Top_News/World-News/2026/05/07/latam-hantavirus-rising-cases-Argentina-Chile/3071778180123/

CDC. About Hantavirus. Op. cit.

StatPearls. Hantavirus Pulmonary Syndrome. Op. cit.

Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Travel has fully returned, and patients are planning international trips again, with a wide range of destinations and styles. On these video visits, the questions almost always start with vaccines or antibiotics. The real foundation of travel medicine is something else entirely: understanding the specifics of the trip. When I talk with someone preparing to travel, I start with where they are going, how long they will be away, what kind of environment they will be in, and whether they have a chronic condition that might change their risk. Those details matter. A medication or vaccine that is essential for one itinerary may be unnecessary for another.

The first step is confirming routine immunizations. MMR, Tdap, influenza, COVID, and varicella should be current for every traveler, regardless of destination. People sometimes think travel preparation means exotic vaccines. But many illnesses that interrupt trips are the same preventable infections we vaccinate against at home. Once routine protection is confirmed, I look at travel-specific vaccines based on destination and activities. Hepatitis A is worth adding for most international travel where sanitation varies. Hepatitis B belongs on the list for long-term travel, healthcare exposure risk, or an uncertain vaccination history. Typhoid covers travel to many parts of Asia, Africa, and Central America. Yellow fever is required for entry into several countries in sub-Saharan Africa and South America, and Japanese encephalitis matters for long stays in rural areas of Asia or frequent outdoor exposure. Ghana is the example I reach for. Yellow fever vaccination is required for entry, and travelers turn up regularly who have never had it and did not know it was mandatory. That gets sorted first, then malaria prevention if the itinerary runs rural. My view: skipping a vaccine that’s actually required for entry is the most avoidable mistake I see. It’s an easy one to catch, too, if we go through the itinerary first.

Rabies vaccination before travel is another example of something that depends heavily on the details. Someone visiting large cities in Europe for a week has almost no need for it. Someone staying in remote areas, volunteering with animals, or hiking in places where medical care is difficult to access may benefit from receiving it ahead of time. Exposure risk drives that decision, not the destination’s reputation.

Antibiotics come up frequently, and this is where expectations and guidelines often differ. Many travelers assume an antibiotic is something they should take with them in case they get sick. In reality, travelers diarrhea is the most common illness during international travel. Most mild cases respond to hydration and over the counter medications rather than antibiotics. When antibiotics are appropriate, the choice depends on symptom severity and regional resistance patterns. Rural Cambodia is the one that comes up. Travelers remember taking ciprofloxacin on a previous trip and want it again. Updated resistance data has made ciprofloxacin a poor choice there, so the plan changes, and food and water safety carries more of the load. My own bias here. I’d rather a patient carry the right antibiotic and never use it than assume hydration will be enough on a five-day trek.

For a basic travel kit, I usually start with acetaminophen and ibuprofen, which cover pain, fever, and the aches that come with viral illnesses; for gastrointestinal symptoms, loperamide and bismuth subsalicylate handle most mild travelers diarrhea, and oral rehydration salts matter just as much, since dehydration from diarrhea or heat is often the bigger problem than the diarrhea itself. If nausea or motion sickness is a concern, I’ll prescribe ondansetron ahead of time. For moderate or severe diarrhea, azithromycin or a clinician-selected alternative is the antibiotic I reach for, not something to use for every loose stool. Acetazolamide comes up for rapid ascent or high-altitude destinations. For malaria prevention, the choice sits between atovaquone-proguanil, doxycycline, and mefloquine. It depends on the region, the length of the trip, and the traveler’s medical history. Antihistamines and intranasal steroids round out the kit for anyone with seasonal or environmental triggers.

Safety planning is a major part of effective travel preparation, but it often gets the least attention; we discuss how to carry a medication list, a brief summary of medical conditions, and insurance information, along with knowing how to access care in the destination country. Food and water hygiene still matters in many regions. So does mosquito protection for illnesses like dengue and chikungunya that do not have widely recommended vaccines for travelers. For destinations with malaria risk, prophylactic medications and mosquito avoidance measures remain a core part of the plan; and for high altitude trips, preventive medications can help if ascent is rapid or unavoidable. If I had to rank these, food and water discipline prevents more sick days than any pill I prescribe. A basic first aid kit rounds this out: adhesive bandages for cuts, scrapes, and blisters; sterile gauze and medical tape for larger wounds; antibiotic ointment to prevent minor wound infections; hydrocortisone cream for itching and insect bites; alcohol or antiseptic wipes to clean a wound before dressing it; tweezers for splinters or ticks; an elastic compression wrap for sprains or mild injuries; a digital thermometer, essential for evaluating fever or illness on the road; and gloves for basic hygiene when handling a wound.

Many travelers also assume they need more than they actually do. Someone visiting Western Europe with up to date routine vaccines usually does not need any additional travel specific vaccines. Travelers often believe they need antibiotics for every trip or that malaria medication protects them from dengue or chikungunya. Which it does not. Correcting these misconceptions is, in my view, as valuable as any vaccine I give: it keeps people from paying for protection they don’t need.

Combine all of this with a clear discussion of itinerary, health history, and realistic risk. Most travelers leave the visit feeling better prepared, not overwhelmed by unnecessary steps. Travel medicine should be individualized. What someone needs for a two week trip to Western Europe is very different from what is needed for remote backpacking in Southeast Asia or trekking at high altitude in Peru. Once the plan matches the destination, everything else becomes much clearer.

Scott Rennie, D.O.

Sources

CDC Yellow Book (cdc.gov)

CDC Travel Vaccine Guide (cdc.gov)

CDC Travelers Diarrhea (cdc.gov)

WHO Travel and Health (who.int)

WHO International Travel Requirements (who.int)

UPMC Travel Health (upmc.com)

TravelHealthPro (travelhealthpro.org.uk)

National Library of Medicine Travelers Diarrhea Review (ncbi.nlm.nih.gov)

Pyllola Travel Vaccines Guide (pyllola.com)

Immunize.org Travel Vaccines (immunize.org)

Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Doctor Rennie's Blog

Tag: global health

What Is Hantavirus? What You Need to Know Right Now