Lyme disease is widely considered a "clinical" diagnosis, based on symptoms, physical findings and the possibility of exposure to infected ticks. Lyme disease can be a multi-system disease affecting one, or many organ systems, including the joints, gastrointestinal, neurological, ophthalmological, cardiac, the eyes, and more. Symptoms can change quickly and come and go (first it's headaches, then joint pains). Symptom checklists are available through Lyme and Related Tick-borne disease medical treatment guidelines.
Complicating things further, Lyme disease often mimics the symptoms of other diseases. Misdiagnoses include: Chronic Fatigue Syndrome, Lupus, Rheumatoid Arthritis, Fibromyalgia, Alzheimer’s, ADD/ADHD, Autistic-Spectrum Disorder, Psychiatric illnesses such as Depression and Anxiety Disorder, and Neurological illnesses such as Multiple Sclerosis, Parkinson’s and more. Many of these diseases do not have gold-standard tests, which means that a Lyme disease evaluation relies heavily on their clinical judgment, the physician’s knowledge and experience with these diseases.
Ticks can also transmit multiple diseases. Therefore, when being evaluated for Lyme disease, patients should also be evaluated for other Lyme strains e.g. Borrelia myamotoi, and common coinfections like Anaplasmosis, Bartonella, Babesia, Ehrlichia, Mycoplasma, Q Fever, Rocky Mountain Spotted Fever, Tularemia and more. Some of these symptoms overlap with Lyme, and some are quite unique which can help in the proper diagnosis.