A health care provider will consider your symptoms, possible exposure to infected ticks, and whether another condition could be causing your symptoms. A characteristic erythema migrans rash may support a diagnosis without blood testing.

When testing is appropriate, providers generally use a 2-step blood test that looks for antibodies to the bacteria that cause Lyme disease. Because these antibodies take time to develop, testing may be negative during the first few weeks of infection.

Depending on your symptoms, a provider may recommend additional tests to check for complications affecting the heart, nervous system, or joints.

Not necessarily. Lyme disease remains most common in the Northeast, mid-Atlantic, and upper Midwest, but cases also occur elsewhere, including along the Pacific Coast. The geographic range of reported cases has expanded, and warmer conditions are one factor influencing where ticks can survive and how long they remain active.

You could also encounter an infected tick while traveling. A healthcare provider will consider your recent locations, possible tick exposure, and symptoms rather than ruling out Lyme disease based on your home address alone.