<P> Each year, approximately 30,000 new cases are reported to the CDC however, this number is likely underestimated . The CDC is currently conducting research on evaluation and diagnostics of the disease and preliminary results suggest the number of new cases to be around 300,000 . </P> <P> Lyme disease is the most common tick - borne disease in North America and Europe, and one of the fastest - growing infectious diseases in the United States . Of cases reported to the United States CDC, the ratio of Lyme disease infection is 7.9 cases for every 100,000 persons . In the ten states where Lyme disease is most common, the average was 31.6 cases for every 100,000 persons for the year 2005 . </P> <P> Although Lyme disease has been reported in all states about 99% of all reported cases are confined to just five geographic areas (New England, Mid-Atlantic, East - North Central, South Atlantic, and West North - Central). New 2011 CDC Lyme case definition guidelines are used to determine confirmed CDC surveillance cases . </P> <P> Effective January 2008, the CDC gives equal weight to laboratory evidence from 1) a positive culture for B. burgdorferi; 2) two - tier testing (ELISA screening and Western blot confirming); or 3) single - tier IgG (old infection) Western blot . Previously, the CDC only included laboratory evidence based on (1) and (2) in their surveillance case definition . The case definition now includes the use of Western blot without prior ELISA screen . </P>

Where is lyme disease found in the us