Introduction Lyme disease, caused by the bacterium Borrelia burgdorferi, is the most common tick-borne illness in the United States, Europe, and parts of Asia. Transmitted primarily by the blacklegged tick (also called the deer tick), the risk of infection is heavily influenced by geography. Understanding where Lyme disease is most prevalent can help individuals, families, and pet owners take proactive steps to protect themselves. This article explores the global and regional spread of Lyme disease, with a special focus on high-risk areas, reasons for its expansion, and practical prevention strategies. What Determines the Geographic Spread of Lyme Disease? The spread…