Hantavirus (ongoing)

Hantavirus occupies a unique position in the landscape of infectious diseases: it is simultaneously rare and terrifying, with mortality rates that rival Ebola, a mode of transmission that makes it nearly impossible to fully prevent, and a global distribution that ensures sporadic outbreaks on every inhabited continent. The virus was formally identified in 1993 during an outbreak in the Four Corners region of the American Southwest — where Arizona, Colorado, New Mexico, and Utah meet — but genetic evidence shows that hantaviruses have been infecting humans for centuries, circulating silently in rodent populations worldwide.

The pathogen is not a single virus but a family of related viruses, each associated with a specific rodent reservoir. In the Americas, the Sin Nombre virus (carried by deer mice) causes Hantavirus Pulmonary Syndrome (HPS), a respiratory illness with approximately 35% mortality — one of the highest case fatality rates of any disease circulating in North America. In South America, Andes virus — notable as the only hantavirus known to transmit between humans, not just from rodent to human — causes a similar syndrome and has been responsible for outbreaks in Argentina and Chile, including the 2026 MV Hondius cruise ship cluster that linked cases across multiple countries.

In Europe and Asia, different hantavirus strains cause Hemorrhagic Fever with Renal Syndrome (HFRS), a distinct disease characterized by kidney failure rather than lung damage. The Hantaan virus (Korea, China) and Puumala virus (Scandinavia, Western Europe) are the main culprits, causing tens of thousands of HFRS cases annually, primarily in agricultural workers who come into contact with rodent excreta in fields and forests.

Transmission occurs when humans inhale aerosolized particles from infected rodent urine, feces, or saliva — or when they handle contaminated material without respiratory protection. There is no person-to-person transmission for most strains (the Andes virus being the exception), which limits epidemic potential. The risk is highest during activities that disturb rodent habitats: cleaning out sheds and barns, camping in rodent-infested areas, harvesting crops by hand, or — as demonstrated aboard the MV Hondius — inhabiting enclosed spaces with rodent infestations.

The 2026 MV Hondius outbreak marked a significant moment in hantavirus epidemiology. The cruise ship, which had departed from Ushuaia, Argentina, recorded multiple cases of Andes hantavirus among passengers from at least five countries. With 11 confirmed cases and 3 deaths — and the Andes virus's known person-to-person transmission capability — health authorities in the UK, Spain, France, the United States, Argentina, and Chile activated quarantine and monitoring protocols. The WHO issued Disease Outbreak News (DON601) confirming the cluster. This international dimension was unprecedented for hantavirus and underscored the risk that rodent-borne diseases pose in an era of global travel.

There is no specific antiviral treatment for any hantavirus infection, and no approved vaccine outside of China (where a killed whole-virus vaccine for HFRS has been in use since the 1990s). Management is supportive: mechanical ventilation for HPS, dialysis for severe HFRS. Early recognition is critical and difficult, because initial symptoms — fever, muscle aches, fatigue — are indistinguishable from influenza.