A Virginia Tech disease ecologist said the outbreak of Andes hantavirus aboard the international MV Hondius cruise ship underscores how little scientists still know about the viruses circulating silently in wild rodent populations before they spill into humans.
While most hantaviruses infect humans through animal-to-human transmission, the Andes strain is capable of spreading between people, highlighting global vulnerabilities in interconnected travel networks.
“Viruses with the ability to infect multiple species and spread silently between people deserve serious attention before outbreaks grow larger,” said Virginia Tech disease ecologist Luis Escobar. “Most of our research on zoonotic viruses remains reactive, we study them after they spill over into humans instead of understanding how they circulate in wildlife beforehand.”
While most hantaviruses that infect humans originate from animal-to-human transmission, the Andes strain is capable of spreading between people, highlighting global vulnerabilities in interconnected travel networks.
Escobar discussed the unique biology of the virus and why current public health models often fail to predict spillover events.
How does the Andes hantavirus differ from European and Asian variants?
Our research reveals that hantaviruses from Europe and Asia tend to remain more closely tied to their original rodent hosts. However, variants in the Americas show greater ecological plasticity, meaning rodents can transmit the virus across a broader range of species. This biological flexibility is a major warning sign for disease emergence. That said, the ecological and evolutionary mechanisms behind these differences remain unclear, and more research is needed to understand how hantaviruses circulate in wildlife before they spill over into humans and trigger outbreaks.
Why might the official case count underestimate the true size of the outbreak?
Hantaviruses can produce asymptomatic or mild infections in addition to severe illness, but it is unclear the potential role of silent infections in disease spread. Because hospitalization data only captures the most severe cases, the true size of an outbreak is often underestimated.
Understanding the true size of an outbreak is critical because it directly shapes public health decisions, including containment strategies, surveillance, and risk assessment.
Why is hantavirus compared to illnesses like COVID-19 and Avian Flu?
Like those respiratory viruses, hantavirus can trigger an excessive inflammatory response. In severe cases, the immune system essentially goes into overdrive, causing the lungs to fill with fluid even without widespread destruction of lung tissue.
Do we know whether the virus linked to the cruise ship outbreak is circulating elsewhere in North America?
The genetic sequence linked to the outbreak cluster with Andes hantavirus found in Chile and Argentina has not been released. At this stage, we only know that the outbreak is associated with a hantavirus capable of causing pulmonary syndrome.
Is concern over hantavirus being exaggerated?
History shows that underestimating a virus early on, like the COVID-19 pandemic, contributes to delayed action. The U.S. National Academy of Medicine warns the world remains poorly prepared for another pandemic. Environmental change and increased human mobility mean we should expect more—not fewer—outbreaks linked to wildlife-origin pathogens.
Does Andes hantavirus truly have pandemic potential?
Yes, for several reasons:
● It can spread from person to person
● It has an incubation period that may allow silent transmission
● There is no vaccine currently available
● Treatment is largely supportive or palliative
But not all the infected people will necessarily transmit the virus (High viremia may be needed for viral spread), and when local epidemiologists have the resources and authority to intervene, hantavirus outbreaks have been contained successfully.
What is the mortality rate?
It is significantly higher than COVID-19. In parts of southern Chile, mortality among hospitalized patients can approach 60%. This high fatality rate makes rapid containment and international coordination essential.
That means rapid containment is essential. The earlier outbreaks are identified and controlled, the better the outcome for global public health.
Is there evidence that the virus has mutated to spread more easily?
I have not seen evidence that viral change plays a role in the transmission. Instead, it seems that human behaviors are more important to facilitate the transmission. Researchers need more baseline data on hantaviruses in wild rodents to determine if new outbreaks are driven by viral evolution, environmental changes, or increased human exposure.
