In 2022, the United States saw a significant increase in reported cases of Lyme disease following the implementation of a revised surveillance case definition. The new approach allowed high-incidence jurisdictions to report cases based solely on laboratory evidence, eliminating the need for additional clinical information. The changes resulted in a 68.5% increase in reported cases compared to the annual average between 2017 and 2019.

Lyme disease, a tickborne illness caused by Borrelia spirochetes, is the most prevalent vectorborne disease in the US. The majority of cases, approximately 90%, are reported from 15 high-incidence jurisdictions located in the Northeast, mid-Atlantic, and upper-Midwest regions. Prior to the revised case definition, surveillance for Lyme disease required the collection of clinical information, which proved to be a challenging task for some high-incidence jurisdictions due to the increasing number of infections.

The revised case definition, implemented on January 1, 2022, allowed high-incidence jurisdictions to report cases based solely on laboratory evidence. As a result, a total of 62,551 Lyme disease cases were reported to the Centers for Disease Control and Prevention (CDC) in 2022. This is a significant increase compared to the annual average of 37,118 cases reported during 2017-2019. The majority of reported cases (95.5%) were from high-incidence jurisdictions, reflecting the impact of the revised surveillance method.

The increase in Lyme disease cases in 2022 is primarily attributed to changes in surveillance methods rather than a change in disease risk. The new approach improves standardization of surveillance practices across jurisdictions but makes it challenging to compare data with historical records. Additionally, the increase in reported cases was more prominent among older age groups, with adults aged 65 and above experiencing a doubling of incidence compared to previous years.

It is important to note that date of illness onset was rarely available in high-incidence jurisdictions, as laboratory-based reporting without case investigation was the primary method. However, alternative dates related to laboratory testing or reporting still demonstrated seasonality, albeit shifted by two weeks later to reflect the time lag required for a detectable immune response.

While the increase in reported cases indicates progress in surveillance, it is likely that the actual number of Lyme disease cases is higher, as some early cases may not be captured due to the reliance on laboratory evidence and lack of clinical findings. The use of modified two-tier test (MTTT) serologic assays, cleared by the Food and Drug Administration in 2019, might have also influenced the increase in positive laboratory evidence. However, challenges in identifying MTTT assays within existing systems may have resulted in underascertainment of positive laboratory evidence.

The surge in reported Lyme disease cases underscores the continued need for effective prevention methods. The revised surveillance method will enhance data standardization and facilitate comparison across high-incidence jurisdictions. However, it may limit the ability to compare trends with data collected using earlier case definitions. Standardized codes for laboratory evidence identification are critical to ensure accurate surveillance.

As the reported cases of Lyme disease continue to rise, it is essential to prioritize prevention efforts and raise awareness about the risk of tickborne diseases. By implementing comprehensive prevention strategies, individuals can protect themselves and reduce the impact of Lyme disease.

Disclaimer: The article is based on the information provided by the user and does not include any additional research or external sources.