In addition to the policywonk article linked above - here is some more info:
Good testing info:
www.betterhealthguy.com/lyme/testingWhy IGeneX?
IGeneX processes over 20,000 Lyme tests a year, and can adhere to a more specialized structure than the CDC regulations. IGeneX includes band 31 in their testing, and also offers 30-31kDa confirmation-these bands are often positive due to cross-reactivity with other viruses, and IGeneX uses highly specific recombination antigens to validate results. In addition, IgG needs only 2 bands present (instead of 5), and the IgM needs 2 (like the Western Blot).
22 Reasons tests are wrong:
whatislyme.com/22-reasons-why-your-lyme-test-may-be-wrong/-p