NEW YORK  —In 2022, the United Kingdom reported its first confirmed case of tick-borne encephalitis virus. The incident involved a 50-year-old man who had been mountain biking in the North Yorkshire Moors, a picturesque national park in England.

Following the bike ride, the man experienced symptoms typical of a viral infection, including fatigue, muscle pain, and fever, five days after the tick bite.

Although initially showing signs of improvement, the man's condition took a turn for the worse after about a week, as he began experiencing coordination issues. Medical examinations, including an MRI scan, unveiled that he had developed encephalitis, a serious condition characterized by inflammation of the brain.

The cause of his illness was confirmed to be tick-borne encephalitis (TBE), a dangerous disease that experts assert is extending into previously unaffected areas, largely due to the impact of global warming.

Over the last three decades, the United Kingdom has experienced an average temperature increase of approximately 1 degree Celsius (1.8 degrees Fahrenheit) compared to historical norms. This warming trend has been linked to the rise in various tick-borne illnesses, with climate change playing a significant role.

Among these illnesses, tick-borne encephalitis (TBE) is of particular concern to public health officials due to its higher fatality rate compared to more commonly known tick diseases like Lyme disease. What's alarming is the rapid spread of TBE from one country to another, which experts attribute to the impact of climate change.

Gábor Földvári, an expert at the Center for Ecological Research in Hungary, has emphasized the unmistakable influence of climate change on the prevalence and distribution of TBE.

 TBE is becoming a significant health concern in regions affected by global warming. Over the past few decades, TBE has been on the rise in places where it was previously absent, attributed to warmer temperatures allowing ticks to thrive and extend their feeding periods on humans and animals. Milder winters result in ticks being active earlier in the year, leading to increased contact between infected ticks and humans.

TBE was first discovered in the 1930s and is mainly found in Europe and parts of Asia, with its transmission primarily through tick bites and occasionally through consuming raw milk from infected cattle. Although TBE has not been identified in the United States, a few cases have been reported in Americans who traveled to affected regions in Europe.

The World Health Organization estimates that Europe and northern Asia experience between 10,000 and 12,000 TBE cases annually, with the global burden likely underreported due to low awareness of the disease in certain areas and limited reporting to health authorities. Since the 1990s, there has been a notable increase in TBE cases, especially in countries where the disease was once uncommon.

TBE is on the rise in several European countries, with severe cases increasing and some leading to death. About 10% of TBE infections become severe, and survivors may experience lingering neurological problems.

Although two vaccines exist, their uptake is low in newly affected regions, and experts urge the development of more effective vaccines. Rising global temperatures have expanded tick-friendly environments, contributing to the spread of TBE in central and northern Europe.

The growing presence of TBE across Europe, Asia, and parts of the United Kingdom highlights the dangers of tick-borne diseases, emphasizing the need for vigilance and research as climate change continues to affect disease transmission.