From the CDC:
How are cases reported to CDC?
As with most other reportable diseases, reporting requirements for Lyme disease are determined by state laws or regulations. In most states, Lyme disease cases are reported by licensed health care providers, diagnostic laboratories, or hospitals. States and the District of Columbia remove all personally identifiable information, then share their data with CDC, which compiles and publishes the information for the Nation. CDC has no way of linking this information back to the original patient.
CDC summarizes national surveillance data based on these reports, and publishes results in the CDC publication, the Morbidity Mortality Weekly Report. The latest summary was published in theMMWR Surveillance Summary for Lyme Disease–United States, 1992-2006.
The goal of Lyme disease surveillance is not to capture every case, but to systematically gather and analyze public health data in a way that enables public health officials to look for trends and take actions to reduce disease and improve public health.
Are more recent numbers available?
Cases of Lyme disease and other reportable conditions are published each week in the MMWR. However, these weekly numbers are provisional and often change when all the data become available after the end of the year. CDC publishes finalized data only after all states and territories have certified their reports. Finalized data for a given year are generally not available until the fall of the following year.
What is a surveillance case definition?
Reporting of all nationally notifiable diseases, including Lyme disease, is based on standard surveillance case definitions developed by the Council of State and Territorial Epidemiologists (CSTE) and CDC. The usefulness of public health surveillance data depends on its uniformity, simplicity, and timeliness. Surveillance case definitions establish uniform criteria for disease reporting and should not be used as the sole criteria for establishing clinical diagnoses, determining the standard of care necessary for a particular patient, setting guidelines for quality assurance, or providing standards for reimbursement. The national surveillance case definition for Lyme disease is available on CDC’ s web site.