Climate change is increasing the prevalence of obscure tick-borne viruses.

Climate change is increasing the prevalence of obscure tick-borne viruses.

Tick-Borne Encephalitis: Spreading Disease Linked to Climate Change

It began with a bike ride. A 50-year-old man was exploring the North Yorkshire Moors, a picturesque national park in England known for its woodlands and purple heather. Little did he know that a tiny black-legged tick burrowed into his skin, setting off a chain of events that would change his life and shed light on a growing public health concern.

Symptoms initially resembled a viral infection – fatigue, muscle pain, and fever. But as the days passed, the man’s condition worsened. He started experiencing coordination problems, prompting further investigation. An MRI scan uncovered the alarming truth – he had contracted tick-borne encephalitis (TBE), a potentially fatal disease that is on the rise due to global warming.

The Impact of Climate Change on TBE

Over the past three decades, the UK has seen an average temperature increase of about 1 degree Celsius, primarily due to climate change. This rise in temperature has been linked to the increasing prevalence of tick-borne illnesses, including TBE. Public health officials are particularly concerned about TBE, as it is more deadly compared to other well-known tick diseases, such as Lyme disease.

Gábor Földvári, an expert at the Center for Ecological Research in Hungary, highlights how climate change has unmistakably affected TBE’s spread. “It’s a really common problem which was absent 20 or 30 years ago,” he explains. Ticks cannot survive temperatures below freezing, but they thrive in warm and humid conditions. As global warming extends the duration of warm weather and milder winters, ticks become active earlier in the year. This, in turn, increases their chance of feeding on humans and animals, thereby spreading diseases.

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Gerhard Dobler, a doctor at the German Center for Infection Research, emphasizes that climate change impacts ticks at every stage of their life cycle and amplifies disease transmission. He states, “The number of overwintering ticks is increasing, and in spring there is high tick activity. This may increase the contact between infected ticks and humans and cause more disease.”

The Global Spread of TBE

While TBE was first discovered in the 1930s and mainly found in Europe and parts of Asia, the disease has been rapidly expanding its reach thanks to ticks. Different regions have different subtypes of the virus, but the tick species remains the same. Tick bites are the primary cause of TBE, but the virus can also be acquired by consuming raw milk from infected cattle. Although TBE has not been found in the United States, a few Americans have contracted the virus while traveling in Europe.

According to the World Health Organization, there are between 10,000 and 12,000 cases of TBE reported each year in Europe and northern Asia. However, these numbers likely underestimate the actual caseload due to low awareness and reporting in some countries. There has been a clear upward trend in cases since the 1990s, especially in countries where TBE was previously uncommon. Dobler cites rising cases in Austria, Germany, Estonia, Latvia, and other European countries.

Understanding TBE: Symptoms, Treatment, and Prevention

TBE can range from mild to severe, with severe cases often requiring hospitalization. Once severe symptoms manifest, there is currently no cure for the disease. The death rate varies based on the virus subtype, ranging from 1 to 35 percent. Those who survive severe TBE may face lingering neurological problems, such as sleeplessness and aggressiveness.

While there are two TBE vaccines available, vaccine uptake is low in regions where the virus is still new. Additionally, neither vaccine covers all prevalent subtypes, calling for the development of a more comprehensive vaccine. A 2020 study indicated the need for an improved vaccine offering higher protection against the virus. Despite Austria’s high TBE vaccine rate of around 85 percent, the number of human cases continues to rise. This suggests that climate change plays a significant role in the disease’s prevalence, according to Dobler.

Spreading Shadows: TBE’s Impact Across Europe and the UK

Central and northern Europe have experienced average annual temperature increases of around 2 degrees Celsius compared to the pre-industrial era. These regions have witnessed a rise in TBE cases over the past few decades, indicating a correlation between rising global temperatures and tick activity. Tick populations are also expanding their geographical range, venturing further north and higher in altitude. For instance, previously tick-free mountains in Germany, Bavaria, and Austria have reported a 20-fold increase in cases over the past decade.

The growing shadow cast by TBE across Europe, Asia, and now parts of the United Kingdom heightens concern about tick-borne diseases. The UK’s first domestically acquired case of TBE serves as a stark warning. Although the virus remains rare, it may not stay that way for long.

Conclusion

Tick-borne encephalitis is an increasingly significant public health issue exacerbated by climate change. As global temperatures rise, ticks thrive, spreading diseases such as TBE. The expansion of TBE’s reach and its impact on affected individuals highlight the urgent need for awareness, prevention, and improved vaccines. This intersection between climate change and infectious diseases emphasizes the necessity of addressing environmental concerns in the pursuit of public health and wellbeing.