The Myth of the Bullseye: Why Recognizing the Spectrum of Lyme Disease Rashes is Critical for Diagnosis and Treatment

Lyme rashes
By Bay Area Lyme Foundation

BAL Spotlights Series

 

Anna Schotthoefer, PhDAnna Schotthoefer, PhD, a project scientist at Marshfield Clinic Research Institute in Wisconsin, discusses the collection and analysis of a specific subset of blood and urine samples for Lyme Disease Biobank—a Bay Area Lyme Foundation program—from patients diagnosed with tick-borne diseases in the state. Marshfield Clinic serves a large population in Wisconsin and Michigan’s Upper Peninsula, which are highly endemic for Lyme disease. Her Bay Area Lyme-funded study of the Marshfield samples focused on visual documentation of rashes associated with Lyme disease and the challenges in accurately diagnosing the disease based on these rashes. The results highlight the difficulties in recognizing early Lyme: only two of 69 patients presented with the classic bullseye rash that doctors learn is the gold standard for diagnosing Lyme from textbooks. Schotthoefer discusses the variety of different rashes that can result from a tick bite, the characterization of the spectrum of rashes, the need for better Lyme diagnostics, and the ongoing efforts to develop new testing methods using the samples collected in LDB. She expresses optimism that in the next five to ten years, there will be significant advancements in Lyme disease detection, diagnosis, and therapeutics—largely thanks to patients who have contributed samples to LDB for ongoing research.

“The textbooks doctors read in medical school tell them, ‘Look for a bullseye rash; look for the target-like lesion,’ and it turns out that’s wrong. There is a need to continue educating clinicians and providers that Lyme rashes are a spectrum.”

– Anna Schotthoefer, PhD

Inadequacy in the medical field to accurately diagnose a Lyme rash

By Bay Area Lyme Foundation

– Wendy Adams, Research Grant Director, Bay Area Lyme Foundation

Erythema migrans (EM) is the hallmark sign of infection with B. burgdorferi. An EM is defined as an expanding annular (round) lesion or rash of at least 10cm (2.5in). Most rashes occur 3–30 days after infection, however there are case reports that show EMs can appear sooner than three days post infection.

The term “bullseye” rash is often used synonymously with EM. But an EM is not required to have central clearing or a target appearance. The rash can take many forms, and may have a raised bump in the middle, can be itchy or warm, and can have a bluish cast like a bruise. It can be round or even oval. Only 20% of Lyme disease with an EM have the bullseye presentation. That means that only 1 in 6 total Lyme cases will have a rash with a target appearance.

The rash also may not be present at all. While the Centers for Disease Control and Prevention report that 70-80% of patients may exhibit the erythema migrans, this number can vary by study. For example, a 2010 study showed that in the state of Maine only 43% of Lyme patients exhibited this rash when infected with Lyme.