Climate change set to increase leptospirosis risk across Europe

A new Europe-wide study has warned that Leptospirosis is emerging as a growing public health concern across Europe, with climate change expected to increase infections, expand the disease’s geographic spread and lengthen its transmission season.

The research, described as the first spatiotemporal modelling study of leptospirosis risk across Europe, analysed epidemiological, environmental and climate data to assess how changing weather conditions could influence the disease in the coming decades.

Leptospirosis is a bacterial disease caused by Leptospira bacteria and is transmitted from animals to humans, most commonly through urine from infected rodents. Livestock and pets can also spread the infection. Humans typically contract the disease through contaminated water, soil or food, especially after floods or in areas with poor sanitation.

Cases rising across Europe

Between 2010 and 2023, Europe recorded 3,930 leptospirosis cases — an average of around 281 annually. About 140 NUTS 3 regions reported infections each year, with both the number of cases and affected regions showing a clear upward trend.

Although Europe’s incidence remains far lower than in tropical regions, researchers warned the disease is likely underdiagnosed and underreported, meaning the actual burden could be significantly higher.

The illness can lead to severe complications, including multi-organ failure, and around 42% of confirmed European cases required hospitalisation. Globally, leptospirosis is estimated to cause roughly one million infections and about 60,000 deaths each year.

Climate change driving risk

The study found that warmer temperatures and wetter conditions strongly increase leptospirosis transmission.

Higher temperatures had the greatest impact, with infection risk increasing up to fivefold in some conditions, while increased rainfall and flooding also created favourable environments for bacterial survival and rodent populations.

Researchers said climate change is altering environmental conditions, reservoir dynamics and pathogen survival, contributing to a broader and more unpredictable disease risk across Europe.

Future projections

Under all future climate scenarios examined, leptospirosis cases are projected to rise.

Researchers expect moderate increases between 2041 and 2060, with much sharper rises projected by 2081–2100, particularly under high greenhouse gas emission scenarios.

Around 70% of European regions are expected to experience increases in disease incidence.

The transmission season is also likely to expand beyond its current late-summer peak. Future risks are projected to spread into winter and spring months, increasing the duration of exposure each year.

Expanding geographic spread

From 2010 to 2023, the highest infection rates were recorded in warm coastal and densely populated areas, with peaks in August and September.

However, the study predicts that northern and central European regions — historically less affected because of cooler climates — could become increasingly suitable for transmission as temperatures rise.

While some parts of southern Europe may see localised declines due to hotter and drier conditions reducing bacterial survival, the broader trend points toward a wider seasonal and geographic spread of the disease across the continent.