Ask the Expert: The real risk of hantavirus

Luis Ostrosky, MD, is professor and division chief of infectious diseases at McGovern Medical School at UTHealth Houston. He also serves as chief epidemiology officer for Memorial Hermann Health System. (Photo by UTHealth Houston)

Welcome to Ask the Expert, a UTHealth Houston newsroom series in which leading physicians examine pressing health challenges. In this edition, we address a hantavirus outbreak linked to a cruise ship.

The Dutch cruise ship MV Hondius garnered national attention after patients were sickened by the Andes virus, a strain of hantavirus. Of the 150 on board, three passengers have died, and several others are being monitored for symptoms. According to the Associated Press, Argentina’s leading hypothesis is that a Dutch couple contracted the virus during a bird-watching outing at a garbage dump before boarding. Currently, five U.S. states are monitoring cruise passengers for hantavirus. No cases have been reported in the U.S., and the risk to Americans remains low.

What is hantavirus, and what strain is involved?

Hantaviruses are RNA viruses that typically spread through rodents. There are two main groups: “New World” hantaviruses, found in the Americas, and “Old World” hantaviruses, found in Asia and Europe. For both groups, human infections are usually incidental and occur when someone inhales viral particles from rodent droppings, often while cleaning enclosed spaces such as cabins or sheds.

New World hantaviruses tend to cause severe lung disease, including hantavirus pulmonary syndrome. Old World hantaviruses are more commonly associated with hemorrhagic fever and kidney failure.

These viruses have existed for decades, if not centuries, and cases are reported sporadically in the United States. While rare, there have been instances of human-to-human transmission, particularly with the Andes virus in South America. This is the strain believed to be responsible for the outbreak on the cruise ship.

How contagious is it?

There are a few documented cases in the medical literature of human transmission. For example, individuals who were infected from rodent exposure and became severely ill attended social gatherings where others later became sick. In those cases, the infected individuals had high levels of virus in their bloodstream and were already symptomatic.

Unlike COVID-19 or influenza, hantavirus is not typically airborne and is not spread before symptoms appear. Transmission generally requires close, prolonged contact with someone who is visibly ill, often involving exposure to bodily fluids.

It is not nearly as infectious as common respiratory viruses. The average incubation period is about 15 days but can range up to 45 days.

What symptoms should people watch for?

Initial symptoms are similar to a flu-like illness, with patients experiencing fatigue, fever, and muscle aches. Many patients also experience gastrointestinal symptoms such as abdominal pain and diarrhea.

The illness can progress to a respiratory phase marked by a dry cough, shortness of breath, and high fever. In some cases, this progression happens rapidly–within hours–and requires urgent medical care.

Patients with severe disease may need intensive care, including intubation and advanced cardiopulmonary support such as extracorporeal membrane oxygenation, or ECMO.

Should Americans be concerned about a COVID-like situation?

No. There is no evidence of sustained transmission in the United States. Individuals who disembarked the ship and entered the U.S. have been identified and are being monitored for symptoms.

What should I do if I think I have hantavirus?

If you suspect you have hantavirus or have been in contact with someone diagnosed with it, call your doctor or go to the nearest emergency room. There is no specific treatment or vaccine, but early medical care is critical.

Seek information from reputable sources, and do not attempt to treat yourself at home. For more information, visit the World Health Organization.

Luis Ostrosky, MD, is professor and division chief of infectious diseases, Memorial Hermann Chair, director of the Laboratory of Mycology Research, and vice chair of medicine for health care quality at McGovern Medical School at UTHealth Houston. He also serves as chief epidemiology officer for Memorial Hermann Health System. All quotes should be attributed to him. 

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