Lyme Disease Surveillance and Data

Key points

Over 63,000 cases of Lyme disease were reported to CDC by state health departments and the District of Columbia in 2022. This number reflects cases reported through routine national surveillance, which is only one way public health officials track diseases. Recent estimates using other methods suggest that approximately 476,000 people may be diagnosed and treated for Lyme disease each year in the United States. This number likely includes patients who are treated based on clinical suspicion but do not actually have Lyme disease.

Female epidemiologist working on data on computer.

Surveillance data explained

Lyme disease has been a nationally notifiable condition in the United States since 1991. Reports of Lyme disease are routinely collected and verified by state and local health departments in accordance with their legal mandate and surveillance practices. After removal of personal identifiers, selected information on cases is shared with CDC through the National Notifiable Diseases Surveillance System (NNDSS). Policies regarding case definitions, reporting, confidentiality, and data release are determined by states and territories under the auspices of the Council of State and Territorial Epidemiologists (CSTE). Surveillance data have a number of limitations that need to be considered in the analysis, interpretation, and reporting of results.

  1. Under-reporting and misclassification are features common to all surveillance systems. Not every case of Lyme disease is reported to CDC, and some cases that are reported may be due to another cause.
  2. Surveillance data are captured by county of residence, not county of exposure.
  3. States may close their annual surveillance dataset at a different time than CDC. Thus, the final case counts published by CDC may not exactly match numbers published by each state agency for a given year.
  4. Following its implementation in 1991, the national surveillance case definition for Lyme disease was modified in 1996, 2008, 2011, 2017, and again in 2022. Some of these changes impacted surveillance data and must be considered when attempting to interpret trends. Case definitions for each period are available.

Alternative data sources

CDC is currently working to establish enhanced surveillance and research platforms for Lyme disease using electronic health records (EHRs) from large healthcare systems in areas of the U.S. with a high incidence of Lyme disease. The Surveillance Based Lyme Disease Network is comprised of partners in healthcare systems from Maine, Massachusetts, Pennsylvania, and Wisconsin. CDC will use these EHR data in concert with traditional public health surveillance data to better understand how Lyme disease affects the American public.