To facilitate the public health and research community's access to NNDSS data on Lyme disease, CDC has developed a public use dataset. Based on reports submitted to CDC, this dataset provides the number of confirmed cases by county for the years 1992���2011, in four 5���year intervals. County tabulation is by American National Standard Institute (ANSI) [formerly Federal Information Processing Standard (FIPS)] codes. County codes of "0" represent "unknown" county of residence within each state. More recent county-level case counts are not publicly available at this time.