The progression of Lyme disease is typically divided into three stages: (2)

Stage 1 Localized Lyme disease, in which the infection is focused in one area of the body.Stage 2 Early disseminated Lyme disease, in which the bacteria has begun to spread.Stage 3 Late disseminated Lyme disease, in which the bacteria has spread throughout the body.

Erythema migrans is the earliest sign of the disease in about 70 percent of Lyme disease cases reported to the Centers for Disease Control and Prevention (CDC). (3) There are certain characteristics that can help identify erythema migrans:

It begins as a flat or slightly raised red spot at the site of the tick bite, and can expand to become a round rash up to 12 inches (30 centimeters) or more across.It can appear on any area of the body (at the bite site) but most frequently shows up on the lower limbs, buttocks, and groin in adults, and on the head and neck in children.A clear ring may appear around the center of the rash, giving it a bull’s-eye-like appearance (a central circle with a clear ring around it, surrounded by a larger rash).It may be warm to the touch, though rarely painful or itchy.

While the classic Lyme disease rash has a bull’s-eye shape, not all cases of erythema migrans look the same. The patient may develop a red, expanding lesion with a crusting of the skin at the center; multiple red lesions; red, oval-shaped plaques; or a bluish rash. (4) In addition to erythema migrans, people with localized Lyme disease may experience flu-like symptoms, including fever and chills, headache, fatigue, muscle and joint pains, a general ill feeling (malaise), and swollen lymph glands. About 20 percent of people with Lyme disease don’t experience any symptoms other than erythema migrans. In early disseminated (stage 2) Lyme disease, which occurs weeks to months after the tick bite, other symptoms may develop, including:

Additional erythema migrans lesionsNerve painFacial or Bell’s palsy, a paralysis or weakness in the muscles on one side of the faceLyme carditis, in which Lyme disease bacteria enter the tissues of the heart and interfere with the normal process that coordinates the beating of the heart; symptoms include palpitations, chest pain, or shortness of breath.

Late disseminated (stage 3) Lyme disease, which develops months to years after the infection begins, may cause:

Arthritis with severe joint pain and swelling, especially in large joints such as the kneesPain in the tendons, muscles, joints, and bonesAbnormal muscle movementNumbness and tingling in the hands or feetCognitive problems, including issues with speech and short-term memorySevere headaches and neck stiffness from meningitis (inflammation of the membranes covering the spinal cord and brain)

Vision disturbancesReduced ability to concentrateIrritabilitySleep and memory disordersNerve damage in the legs and arms (neuropathy)

Other non-neurological complications can also develop, such as severe arthritis, persistent fatigue, mood disturbances, and life-threatening disorders of the heart, lungs, and nervous system. It’s likely that you have Lyme disease if you:

Live in an area where blacklegged ticks are commonHave a bull’s-eye-shaped erythema migrans rashHave other common Lyme disease symptoms, in addition to a rash

Your doctor may confirm your diagnosis with laboratory blood tests, or may conduct these tests if you don’t meet all the above criteria. However, if a patient’s symptoms and history suggest that Lyme disease is likely, the doctor will probably begin treatment without waiting for a blood test. The CDC recommends a two-step process for testing blood for the antibodies against Lyme disease: the enzyme immunoassay (EIA) or indirect immunofluorescence assay (IFA), followed by an immunoblot test (Western blot) if the first test is positive. A diagnosis of Lyme disease is made if both the EIA/IFA and the Western blot test are positive. (5) These tests measure antibodies made by the immune system in response to the Lyme infection. However, laboratory testing for Lyme disease can be inaccurate because it can take weeks for an infected patient’s body to create a detectable immune response. If the test is administered before the body develops these antibodies, the results will be negative even if the person has Lyme disease. (6) Plus, lab tests for Lyme disease can be falsely positive when you have other infectious diseases and autoimmune diseases. In general, Lyme tests can be difficult to interpret because of their limitations. Additional reporting by George Vernadakis.