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Quick answerHow common is Lyme disease?
The numbers behind Lyme disease in the U.S.: estimated cases, reported cases, why the counts differ, and where risk is highest.
Quick answer
Lyme disease is common in parts of the United States. CDC estimates that about 476,000 people may be diagnosed and treated for it each year, based on insurance data, and says this may be an overestimate. States reported 89,468 cases to CDC in 2023. Most cases happen in the Northeast, mid-Atlantic and upper Midwest.
- Insurance claims suggest about 476,000 people may be diagnosed and treated for Lyme disease each year; CDC notes billing codes do not always reflect a confirmed diagnosis (CDC).
- In 2023, states and jurisdictions reported more than 89,000 cases to CDC.
- The national case definition has changed several times, most recently in 2022, which affects comparisons over time.
The key numbers
| Measure | Number |
|---|---|
| Estimated people diagnosed and treated each year (CDC, insurance data) | About 476,000 |
| Reported cases, 2023 | 89,468 |
| Reported cases, 2022 | 62,551 |
| Average reported cases per year, 2017 to 2019 | 37,118 |
Reported counts come from CDC’s National Notifiable Diseases Surveillance System annual tables.
Why are there two very different numbers?
Reported cases are the ones health departments count and send to CDC. Many cases are never reported, so this number is an undercount. The 476,000 estimate comes from insurance records of people diagnosed and treated. CDC says it may overcount, because a billing code does not always mean a confirmed diagnosis. The true number likely falls somewhere in between, which is why we describe it as “an estimated 476,000 a year (CDC).”
Are Lyme disease cases rising?
Reported cases jumped from an average of about 37,000 a year in 2017 to 2019 to more than 62,000 in 2022 and nearly 89,500 in 2023. Much of the 2022 jump reflects a new national case definition that changed how cases are counted. CDC cautions that changes in the case definition should be kept in mind when comparing years.
Where Lyme disease is most common
Lyme disease is most common in the Northeast, mid-Atlantic and upper Midwest (CDC). Blacklegged ticks in most of the Southeast are almost never infected, though Lyme disease does occur outside the main hotspots, including along the Pacific coast where the western blacklegged tick lives. Check your area on our Lyme risk map or browse Lyme disease by state, such as Lyme disease in Pennsylvania.
When risk is highest
Nymphs, the tiny young ticks behind most infections, are most active from April through July. Adult ticks are most active in early spring and fall. In eastern areas where Lyme is common, bites from infected ticks can happen from spring through fall (CDC). See ticks that carry Lyme disease and prevention tips.
We are collecting real experiences about Lyme disease in their community from people who have lived it, shared with their permission. As stories come in, they will appear here, clearly marked as personal experience rather than medical advice.
Frequently asked questions
How many people get Lyme disease each year?
CDC estimates about 476,000 people may be diagnosed and treated each year, based on insurance data. States reported 89,468 cases in 2023.
Is Lyme disease rare?
No. In the Northeast, mid-Atlantic and upper Midwest it is common. It is less common in other regions.
Why did Lyme cases go up in 2022?
A new national case definition took effect in 2022, which changed how cases are counted. That accounts for much of the jump in reported cases.