When health officials change how they define a disease, it can shift our entire understanding of it. That's what's happening now with Lyme disease. The Centers for Disease Control and Prevention (CDC) updated its official case definition in 2022, and this report gives us our first peek at the surveillance data collected under those new rules.
The report doesn't provide specific numbers or trends from that first year. It simply confirms that data collection using the revised definition is underway across the United States. The goal is to compare future reports against a baseline of cases from 2017 to 2019, which were counted under the old definition.
This is purely an administrative update. It doesn't mean Lyme disease itself has changed, or that the risk of getting it is different. It means the yardstick for measuring it is new. We don't know yet if this will lead to higher or lower reported case counts, or if it will change which regions appear to have the highest risk. The report offers no conclusions—it's just the starting point for watching how this change plays out in the national data over time.