How many people get Lyme disease?

There is no way of knowing exactly how many people get Lyme disease.  A recently released estimate based on insurance records suggests that each year approximately 476,000 Americans are diagnosed and treated for Lyme disease.1,2 This number is likely an over-estimate of actual infections because patients are sometimes treated presumptively in medical practice. Regardless, this number indicates a large burden on the health care system and the need for more effective prevention measures.

Q: CDC previously estimated that ~300,000 people get Lyme disease each year.3,4 Why is this new number different?

Both estimates are based in part on insurance claims data, however the 476,000 estimate uses more recent information covering the years 2010-2018. In addition, there are some differences in the detailed methods used to develop the two estimates. It’s important to emphasize that 476,000 is the estimated number of people treated for Lyme disease and likely includes some patients who were not actually infected.

Q: CDC also states that approximately 35,000 cases of Lyme disease are reported each year. Why is this number so different?

Each year state and local health departments report cases of Lyme disease to CDC through a passive reporting system, the Nationally Notifiable Diseases Surveillance System (NNDSS). This system provides vital, detailed information for monitoring the geographic, seasonal and demographic features of Lyme disease in the United States. However, because it is a passive system that relies on busy heath care providers to submit records, many cases do not get reported.

Q: How often does CDC plan to estimate how many people get Lyme disease?

As additional robust sources of data become available, CDC will use them to better understand how Lyme disease affects the American public.

References
  1. Schwartz AM, Kugeler KJ, Nelson CA, et al. Evaluation of commercial insurance claims as an annual data source for Lyme disease diagnoses. Emerg Infect Dis. 2021;27(2).
  2. Kugeler KJ, Schwartz AM, Delorey M, et al. Estimating the frequency of Lyme disease diagnoses —United States, 2010-2018. Emerg Infect Dis. 2021;27(2).
  3. Hinckley AF, Connally NP, Meek JI, et al. Lyme disease testing by large commercial laboratories in the United Statesexternal icon. Clin Infect Dis. 2014 Sep 1;59(5):676-81.
  4. Nelson CA, Saha S, Kugeler KJ, et al. Incidence of clinician-diagnosed Lyme disease, United States, 2005–2010. Emerg Infect Dis. 2015;21(9):1625-1631.