Lyme Disease Cases Rose Nearly 70% Due to Reporting Changes

A recent revision in how the Centers for Disease Control and Prevention (CDC) defines a Lyme diagnosis has helped identify cases previous surveillance methods may have missed.

New CDC surveillance data shows an alarming increase in Lyme disease, especially in areas of the United States known for high rates of the tick-borne illness.

The report, released on February 15, shows that the agency received 62,551 reports of Lyme disease in 2022 — a number much higher than the 37,118 cases reported during 2017–2019. The CDC did not include data from 2020 to 2021 due to the impact of the COVID-19 pandemic.


Nearly 96% of reported cases were in states with high incidences of the disease. These include 15 states in the Northeast, mid-Atlantic, and upper Midwest.

The data also showed that males accounted for nearly 60% of the reported cases, and the incidence of the disease among older adults was 2.2 times higher in 2022 than in 2017 to 2019.

However, a change in reporting criteria initiated on January 1, 2022, is likely the reason behind the sharp increase. The changes allowed states where Lyme disease is most prevalent to report new cases based on a positive blood test alone. Previously, state agencies were required to gather clinical data before reporting a Lyme case.

Still, states with lower Lyme disease rates must continue to provide clinical information to support a positive blood test.

In partnership with the CDC, the Council of State and Territorial Epidemiologists (CSTE) revised the national surveillance case definition for Lyme disease to help alleviate the burden of collecting clinical information in states with high illness rates.

The CDC says that without this case definition change, many of these cases identified in 2022 would have been excluded, either because health departments could not obtain the required clinical information or the information did not align with the criteria specified in the Lyme case definition.

Still, despite an increase in reported cases in 2022, the agency says it’s likely that current surveillance does not capture all cases of Lyme disease due to vague symptoms occurring early in the infection and test sensitivity issues.

Moreover, the CDC notes that the higher numbers indicated in the new surveillance data do not come close to the estimated 476,000 Lyme disease diagnoses thought to occur annually in the U.S. — underscoring the need for more effective prevention strategies.


Preventing Lyme disease

There are no vaccines approved to prevent Lyme disease. However, a potential Lyme vaccine candidate called VLA15 is currently under investigation in two Phase 3 clinical trials. Therefore, the primary method of preventing Lyme — and other tick-related conditions — is to avoid being bitten by a black-legged or deer tick, the species that carries the Lyme bacteria.

People can avoid tick bites by applying insect repellents that contain DEET, permethrin, or picaridin on their clothing, staying away from areas that may harbor ticks, like tall grass, and thoroughly checking for ticks after being outdoors.

Despite their best efforts, if a person finds a deer tick attached to their skin, they should carefully remove it and seek medical advice.

Lyme disease experts recommend that anyone bitten by a deer tick should receive a course of an antibiotic called doxycycline to prevent the disease from manifesting.


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