The first sign of Lyme disease is usually a bull's-eye rash that begins from 3 to 30 days after the bite. This circular rash expands to several inches in diameter before disappearing after a few weeks.
Be aware, however, that there's not always a rash, or the rash may look different than a bull's-eye shape.
To diagnose encephalitis, your doctor will consider your symptoms and ask about any recent illnesses and possible exposure to viruses -- being near others who are ill or near mosquitoes or ticks, for example.
Your doctor may also order a magnetic resonance imaging (MRI) scan, spinal tap, or an electroencephalogram (EEG).
Blood tests to check for the presence of bacteria or viruses and immune cells produced in response to them can also be helpful.
Rarely, an analysis of a brain tissue sample...
You may also have vague pains in the joints, without swelling. In about half of people who are not treated, this joint pain returns in about six months as painful arthritis, with swelling in one or both knees. In about 10% of these cases, Lyme arthritis becomes chronic. Some patients also experience a complex range of other symptoms, including stiff neck, headaches, sensitivity to light, memory loss, mood changes, chronic fatigue, recurring rashes, paralysis of one or both sides of the face, disruption of heart rhythm, and areas of tingling or numbness.
In summary, general symptoms may include:
A circular, bull's-eye rash, often with a clear center, expanding to 8 inches or more and lasting 2 to 4 weeks
Any type of rash following a tick bite
Flu-like symptoms such as headache, fatigue, fever, chills, sore throat, and aching muscles and joints
If untreated, you may develop a generalized, painful kind of arthritis, with swelling, weeks later.
See Your Doctor About Lyme Disease If:
You think you may have contracted Lyme disease, especially if you notice a bull's-eye rash or if you suddenly develop knee pain and swelling without previous injury or arthritis. Delaying treatment can result in more serious neurological symptoms that can be difficult and sometimes impossible to cure.