• Warmer, wetter conditions are increasing Lyme disease risk in Germany, especially in areas with deer populations.
• Northern districts saw the sharpest rise in temperature-related risk from 2013–2022.
• The study highlights gaps in disease reporting and the need for stronger disease surveillance across Europe.

Each year, around 200,000 cases of Lyme disease are reported in Western Europe alone. The disease, transmitted by ticks, is closely tied to environmental conditions—ticks are highly sensitive to temperature, humidity, and vegetation changes.

Now, a new study published in eBioMedicine (The Lancet) by researchers at the Barcelona Supercomputing Center (BSC) sheds light on how climate and environmental factors are influencing Lyme disease patterns in Germany. Using national disease notification data and a robust Bayesian modelling framework, the team analyzed how shifting weather patterns and ecological factors affect the dynamics of tick-borne disease.

The study found that maximum temperatures between 10.5°C and 26.3°C, two to four months prior, relative humidity above 78.8% six months prior, and exceptionally wet conditions over three months (lagged by one month) were all associated with an increased risk of Lyme disease. Notably, the effect of humidity was significant only in regions suitable for deer populations, key hosts for adult ticks.

Importantly, the researchers observed an increasing trend in temperature-related Lyme disease risk across all German Federal States. The largest increases between 2013 and 2022 occurred in northern districts, when compared to a historical baseline from 1951-1970. Their model also predicted rising Lyme disease risks in areas of Germany where disease reporting is not mandatory, suggesting under-recognized risk hotspots.

This is one of the few studies to quantify the influence of climate and environmental factors on Lyme disease risk in Europe. As most infections occur close to where people live, the findings highlight the importance of targeted tick control in high-risk forested and urban green areas. Strategies like buffer zones around parks, wildlife monitoring, and citizen science platforms for reporting tick bites can help reduce exposure.

However, many European countries still lack mandatory tick surveillance systems. This study underscores the need to strengthen disease monitoring as climate change continues to reshape the landscape of infectious disease risk.

Reference:

Climate and environmental drivers of Lyme borreliosis risk in Germany: a national spatiotemporal analysis, 2013–22 (eBioMedicine, The Lancet)

Image credit: 

Erik Karits (Creative Commons)