A doctor will usually make the diagnosis based on your symptoms, such as the erythema migrans rash. You might be asked if you have visited an area where catching the disease is possible.

Lyme disease can be difficult to diagnose, especially if you have been bitten by a tick, but do not realize. Therefore, it is important to be aware of the symptoms and the kind of places and activities that can put you at risk, and to be aware of ways to reduce risks.

It is difficult to identify the bacteria, so the internationally recognized criteria for diagnosis of Lyme disease are based on tests that look for specific antibodies (products of a person's immune response to the infection) in the blood. Antibodies may not be found in the first weeks after infection, but in the later stages it is easier to detect them.