Lyme Disease

Lyme is multi-systemic disease caused by infection with a spirochetal bacteria in humans, pets and other animals in the US and worldwide. Lyme disease is caused by many species of Borrelia including but not limited to: Borrelia burgdorferi, Borrelia mayonii, Borrelia afzelii and Borrelia garinii. Borrelia burgdorferi and Borrelia mayonii are the primary strains that cause Lyme disease in the United States, while Borrelia afzelii and Borrelia garinii are the leading causes of Lyme disease in Europe and Asia. Lyme disease is transmitted primarily by the bite of an infected black-legged tick, commonly known as a deer tick and is the most commonly reported vector-borne illness in the United States. The new Colorado Reportable Disease Data interactive database provides an overview of Lyme disease that laboratories are required to report to public health in Colorado, and this data shows over 40 cases of Lyme disease reported in 2025.

Perinatal transmission of Borrelia burgdorferi sensu lato is an alternate mode of transmission between pregnant mother and unborn child, and is an issue of public health importance and research significance. Read 2026 publication Perinatal transmission of Lyme disease: A qualitative study investigating the research priorities of patients with Lyme disease in pregnancy for more information.

Many small mammals, birds and other wildlife act as reservoir hosts for these bacteria. Borrelia infections are then transmitted by the bite of a tick to other animals and humans. Lyme can be a debilitating or even deadly illness if not diagnosed and treated early in the disease process. Preventing tick bites is the best way to avoid this infection but, when prevention measures fail, early recognition of the signs and symptoms of disease, as well as access to accurate diagnosis and adequate treatment is critical to the best outcome.