Researchers from the CDC published a study in February that showed Lyme disease cases jumped nearly 70% in 2022 relative to the annual average from 2017 to 2019. However, that surge was likely driven by streamlined surveillance rather than increased disease risk.
The Centers for Disease Control and Prevention eased reporting requirements of Lyme disease — which can cause fever, fatigue, joint pain, and even neurological issues — two years ago in places where infection rates are high, including the Northeast, mid-Atlantic, and Upper Midwest. Health care workers no longer need to document and report clinical details, such as the start and extent of a patient's symptoms, and simply have to provide proof of a positive test result.
Meanwhile, state health departments are now responsible for all recordkeeping and reporting. Providers in areas where the disease is less common still have to report clinical data.
In 2019, a report by the Environmental Protection Agency stated that Lyme cases doubled from 1990 to 2018, noting that rising temperatures had allowed disease-carrying black-legged ticks to migrate to locations that were once inhospitable to the creature. Warmer winter temperatures have facilitated its spread, and temperate spring and fall seasons have lengthened its breeding period.
"Disease surveillance that is interpretable and is standardized is integral to being able to understand how disease frequency is changing, and if it's changing," CDC epidemiologist and lead author of the paper Kiersten Kugeler said. "It's going to be incredibly important to have good surveillance to be able to understand how climate is affecting risk of disease."
The systematic tweaks resulted in 62,551 reported incidences of Lyme in 2022, 1.7 times the annual average of 37,118 from 2017 to 2019. However, the CDC believes those figures are still far below the estimated 476,000 people in the United States who get Lyme each year.
Some experts said they felt the unreported instances were largely inconsequential since the reported data should be sufficient to find trends. Others said updated guidelines might not be comprehensive enough to understand how rising temperatures are affecting the migratory patterns of ticks.
Regardless, the pros and cons of the revised regulations underscore the challenges in monitoring and managing the spread of diseases such as Lyme that are affected by the ever-changing climate.
"We're likely going to see more and more cases of these diseases and more and more diseases that are going to affect not just our population in the U.S., but globally," Rebecca Osborn, a vector-borne disease epidemiologist at the Wisconsin Department of Health Services, said. "Public health in general needs to become a little more proactive in our responses. We're still working on that as a field."
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