Key points

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 ÐÇ¿ÕÓéÀÖ¹ÙÍø 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.
- Under-reporting and misclassification are features common to all surveillance systems. Not every case of Lyme disease is reported to ÐÇ¿ÕÓéÀÖ¹ÙÍø, and some cases that are reported may be due to another cause.
- Surveillance data are captured by county of residence, not county of exposure.
- States may close their annual surveillance dataset at a different time than ÐÇ¿ÕÓéÀÖ¹ÙÍø. Thus, the final case counts published by ÐÇ¿ÕÓéÀÖ¹ÙÍø may not exactly match numbers published by each state agency for a given year.
- 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. .
Alternative data sources
ÐÇ¿ÕÓéÀÖ¹ÙÍø 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. ÐÇ¿ÕÓéÀÖ¹ÙÍø will use these EHR data in concert with traditional public health surveillance data to better understand how Lyme disease affects the American public.