Post-Treatment Lyme Disease Cases Could Reach 2 Million

Post-treatment Lyme disease cases are rising, and a 2019 study estimates that nearly 2 million Americans may be affected.

This growing number highlights a critical gap in Lyme disease care: many patients continue to experience symptoms despite standard treatment.

For a significant number of patients, standard antibiotic therapy does not fully resolve symptoms. Treatment failure rates may range between 10% and 20%, writes DeLong and colleagues.

These patients can continue to suffer for years with debilitating symptoms, including pain, fatigue, cognitive dysfunction, and other complications. However, the true prevalence of post-treatment Lyme disease remains uncertain.

Estimating Post-Treatment Lyme Disease Cases

To better understand the scope of the problem, the authors used a Monte Carlo simulation along with publicly available data to estimate prevalence in 2016 and 2020.

They found that in 2016, the prevalence of post-treatment Lyme disease ranged from 69,011 to more than 1.5 million cases, assuming a 20% treatment failure rate.

“The number of cases of PTLD is estimated to be 1,523,869 based on the actual number of cases in the USA every year and a linear increase in new cases after 2005,” writes DeLong.

By 2020, the number of cases was projected to be even higher, potentially reaching 1,944,189.

“The cumulative prevalence of post-treatment Lyme disease in the United States is estimated to be high and continues to increase.”

Breakdown of Case Estimates

Assuming a 20% risk:

• 138,540 cases based on CDC-reported data
• 1,351,180 cases based on actual annual infections without growth
• 1,523,869 cases assuming a linear increase after 2005

Assuming a 10% risk:

• 68,603 cases based on CDC-reported data
• 671,876 cases without growth in new infections
• 758,776 cases assuming a linear increase

What This Means for Patients

Conclusions: “Our findings suggest that there are large numbers of patients living with Lyme disease-related chronic illness.”

Because there is no single case definition or shared phenotype, many patients face significant financial burden, as insurance often does not cover long-term care.

Editor’s note: Children ages 5 to 9, particularly boys, are at high risk of Lyme disease. A growing number of post-treatment Lyme disease cases represents a substantial emotional and financial burden for families and the healthcare system.

I am reluctant to use the term PTLDS until there is a reliable test to rule out a persistent infection.

For a broader overview, see Post-Treatment Lyme Disease Syndrome (PTLDS).

Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.

Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention