Fears of a new pandemic erupted this month after the MV Hondius cruise ship became the centre of a deadly hantavirus outbreak off the coast of South America. The World Health Organization (WHO) reports 11 cases and three deaths as of 13 May, with more expected due to the virus’s incubation period. Yet the WHO has stressed there are no signs of a larger outbreak, and transmission remains limited.
Hantaviruses, named after a river in South Korea, are a family of viruses primarily spread by rodents. Most strains cannot pass from person to person, though the Andes virus strain involved in the MV Hondius case has shown rare human-to-human transmission through close contact. A 2018 outbreak in Argentina traced to a party infected 34 people and killed 11.
Climate Change and Rodent Hosts
Climate change is a known amplifier of infectious diseases. A 2022 study in Nature found that more than half of all human infectious diseases are climate-sensitive, including hantaviruses. Changes in rainfall and temperature directly affect rodent populations, which are the primary hosts. “Whenever a disease is climate sensitive, there is the potential for climate change to be influencing its epidemiology,” says Kris Murray, a professor at the London School of Hygiene & Tropical Medicine. Altered rainfall patterns can shift rodent breeding cycles, increasing human exposure.
Habitat destruction, often driven by deforestation, also plays a role. “Removal of vegetation can mobilise infectious pathogens,” Murray explains. Hantavirus is shed in rodent droppings and urine, which can persist in the environment. When habitats are disturbed, the virus can become aerosolized and inhaled. Fragmented ecosystems favour adaptable reservoir species like rodents, while reducing natural ecological balances that regulate pathogen transmission, notes Professor Jörg Schelling of LMU Munich.
In Argentina, a severe drought in 2023–2024 followed by heavy rains created abundant vegetation and food for rodents, likely contributing to a surge in cases: 101 cases and 32 deaths since July 2024, compared to 64 cases and 14 deaths the previous season. The WHO believes MV Hondius passengers may have been infected before boarding.
Europe’s Long History with Hantavirus
Hantavirus is not new to Europe. The first documented outbreak occurred in Sweden in 1934. The most common strain in Europe is Puumala hantavirus, carried by bank voles. It causes a mild form of hemorrhagic fever with renal syndrome, with symptoms like fever, headaches, and abdominal pain. It is rarely fatal and cannot spread between humans.
A 2009 study found that warmer temperatures in West-Central Europe have been linked to more frequent Puumala outbreaks, due to higher seed production and bank vole densities. In Scandinavia, however, warm winters have reduced vole populations by removing protective snow cover. This complexity means climate change could shift risks unevenly across the continent.
“Hantaviruses do occur globally, including in Europe, and it’s conceivable that climate change could create new or increasing opportunities for spillover into people,” Murray says, but he stresses that more research is needed to understand risks at the individual host species level.
European health authorities are monitoring the situation. The recent MV Hondius outbreak has prompted quarantine measures in Tenerife and eased restrictions for negative contacts in Spain. Meanwhile, the UK military air-dropped medics to Tristan da Cunha as a precaution. Experts agree that while hantavirus is not the next pandemic, climate change and habitat loss demand sustained vigilance across Europe.
