A blood test cannot give a direct diagnosis of Lyme disease, but it can help confirm a diagnosis when other symptoms are present. According to the Centers for Disease Control, blood tests ordered are typically the enzyme-linked immunosorbent assay test and the Western blot test.
According to the Mayo Clinic, diagnosis for Lyme disease can be difficult because the symptoms are varied and some are not specific to Lyme disease. Furthermore, Lyme disease is the most common disease spread by ticks, but it is not the only one. Another problem is that negative blood tests can be common in an infected person, because it may take several weeks for antibodies to show up in the blood.
The CDC cite the most common symptom to be a "bull's-eye" rash, which appears in 70 to 80 percent of infected persons within 30 days of infection. Other symptoms are similar to those of a common cold: joint aches, chills, fever, headache and swollen lymph nodes. Less common symptoms include muscle weakness on one or both sides of the face, swelling of the joints, shooting pains and severe headaches.
Once diagnosed, most people recover rapidly and completely with a course of antibiotics.