A rare but potentially deadly virus carried by rodents has once again drawn global attention after recent cases linked to passengers aboard the MV Hondius cruise vessel triggered international health investigations. Scientists say hantaviruses, though uncommon, remain a growing concern as climate change, urbanisation, and environmental disruption increase human contact with wildlife habitats.
According to researchers from Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO), hantaviruses are found on every inhabited continent and are primarily spread by rodents through urine, saliva, and droppings. The animals themselves do not become ill, but humans can develop severe disease after inhaling virus-contaminated particles from dried rodent waste.
Professor Glenn Marsh from the Australian Centre for Disease Preparedness said the viruses represent a classic “One Health” challenge, where human, animal, and environmental health are deeply interconnected.
Two Different Forms of Disease
Experts explain that hantavirus infections generally appear in two major forms depending on the virus strain.
In Europe and Asia, infections commonly cause Haemorrhagic Fever with Renal Syndrome (HFRS), which affects the kidneys. Symptoms include fever, headache, abdominal pain, and, in severe cases, kidney failure and internal bleeding. Certain strains, such as the Hantaan virus found in parts of Asia, can have fatality rates reaching 15 percent.
In North and South America, hantaviruses more often trigger Hantavirus Cardiopulmonary Syndrome (HCS), a far more dangerous respiratory illness. Patients initially experience flu-like symptoms before rapidly developing breathing difficulties as fluid fills the lungs. Mortality rates in HCS cases can exceed 35 percent.
One widely discussed case earlier this year involved the death of Betsy Arakawa in New Mexico, bringing renewed public focus to the disease and its potential presence even in ordinary residential settings.
How the Virus Spreads
Health experts say hantaviruses are mainly transmitted from animals to humans rather than between people. Infection typically occurs when contaminated dust particles become airborne during activities such as cleaning rodent-infested areas, farming, or camping.
Direct contact with infected rodents or rodent bites can also spread the disease, although these routes are less common.
Unlike COVID-19 or influenza, person to person transmission is extremely rare. Scientists note that the Andes virus, found in parts of Argentina and Chile, remains the only known hantavirus capable of spreading directly between humans through close contact.
Australia Remains an Exception
Despite the global presence of hantaviruses, Australia remains the only inhabited continent without any confirmed human cases. However, researchers have detected hantavirus antibodies in some native rodents, suggesting related viruses may exist at low levels.
Scientists believe the absence of diagnosed cases may partly result from mild or overlooked infections that resemble other illnesses.
Experts are urging travellers returning from Europe, Asia, or the Americas to seek medical attention if they develop persistent fever or respiratory symptoms after possible rodent exposure.
Climate Change May Increase Future Risks
Researchers warn that changing climate conditions could expand the geographic spread of hantaviruses in the coming years.
Rodent population explosions linked to heavy rainfall and increased food availability often precede spikes in human infections. At the same time, deforestation, agricultural expansion, and urban growth are pushing humans closer to wildlife habitats, increasing the risk of spillover events.
According to CSIRO scientists, climate-driven environmental changes may expose new regions and populations to hantaviruses for the first time, making surveillance and public awareness increasingly important.
Public health experts continue to recommend basic preventive measures, including proper rodent control, safe cleaning practices, and avoiding direct contact with rodent waste, especially in areas where hantaviruses are known to circulate.