The Testing Gap in Non-Endemic Regions

Researchers from Duke University Health System in North Carolina reviewed the medical records of 1,621 patients, who had a clinical history consistent with Lyme disease and sought treatment at the facility between 2005 and 2010. The authors, who were examining the predictive value of Lyme disease tests, discuss their findings in the July 20, 2015 issue of Clinical Infectious Diseases.

Upon review of the data presented, the reader can better understand the pattern of Lyme disease testing in a non-endemic region. Only 297 patients (18%) of the 1,621 individuals with a “clinical history consistent with Lyme disease” were tested for the disease.

This stunning statistic reveals a fundamental problem: 82% of patients whose clinical presentation warranted Lyme disease consideration received no testing whatsoever. These weren’t vague, non-specific complaints. These were patients whose medical records documented clinical history consistent with Lyme disease—yet the vast majority never underwent diagnostic testing.

Who Was Tested—and Who Wasn’t

The 297 cases consisted of: 110 patients with arthritis of a large joint; 98 patients with cranial nerve palsy; 75 patients with meningitis; 11 patients with both meningitis and cranial neuropathy; 1 patient with arthritis plus cranial nerve palsy; 1 patient with atrioventricular block alone; 1 patient with atrioventricular block plus cranial nerve palsy.

These represent classic, late-stage Lyme disease manifestations. Large joint arthritis—particularly of the knee—is a well-recognized Lyme presentation. Cranial nerve palsy, especially facial nerve palsy (Bell’s palsy), is pathognomonic for Lyme in endemic areas. Meningitis and cardiac conduction abnormalities (AV block) are established Lyme complications.

The fact that only these classic presentations triggered testing reveals geographic bias in action. In endemic regions, physicians test broadly based on compatible symptoms and exposure history. In non-endemic regions, only textbook presentations prompt testing—and even then, only 18% of patients with compatible clinical history received testing.

The Narrow Focus Problem

The authors conceded that their study focused on patients who exhibited conditions most frequently attributable to Lyme disease (LD) and not those who presented with the full clinical spectrum of disseminated Lyme disease. The study did not include patients with well described manifestations of Lyme disease, such as chronic neurologic Lyme disease, Lyme encephalopathy, neuropsychiatric Lyme disease and post-treatment Lyme disease.

This limitation is crucial. The study captured only the most obvious Lyme presentations—conditions so classically associated with Lyme that even clinicians in non-endemic areas might consider testing. It completely excluded:

Chronic neurologic Lyme disease with subtle cognitive impairment, peripheral neuropathy, or radiculopathy. Lyme encephalopathy with memory problems, concentration difficulties, and brain fog. Neuropsychiatric Lyme disease with mood changes, anxiety, depression, or panic attacks. Post-treatment Lyme disease syndrome with persistent fatigue and multisystem symptoms.

These presentations are well-documented in medical literature but don’t appear in the study because they weren’t even considered for testing in this non-endemic setting. The 82% untested rate applies only to classic presentations. For atypical presentations, the untested rate likely approaches 100%.

Why Were 82% Not Tested?

Although the patients exhibited symptoms “most frequently attributable to Lyme disease,” 82% of them were not tested for the disease. The study neglected to examine why these patients did not receive testing. Nor did the authors address where the patients were subsequently diagnosed with LD.

Several factors likely explain the massive testing gap:

Geographic bias—North Carolina is not considered highly endemic by CDC maps, leading clinicians to assume Lyme disease doesn’t occur locally. Lack of awareness—physicians unfamiliar with Lyme disease don’t recognize compatible clinical presentations. Alternative diagnoses—arthritis attributed to rheumatologic conditions, Bell’s palsy attributed to viral infection, meningitis attributed to other causes. Testing cost concerns—reluctance to order “unnecessary” tests for diseases presumed rare in the region. Patient dismissal—symptoms attributed to stress, aging, or psychosomatic causes without investigation.

Without examining why testing didn’t occur, the study misses the opportunity to address systemic barriers to diagnosis in non-endemic regions.

Consequences of Testing Delays

Reports of diagnostic delays remind us of the need to assess patients with clinical history consistent with LD. Treatment delays averaging 1.8 to 2 years have been reported in a case series and Lyme encephalopathy. In the case series, the majority (60%) of cases with delayed treatment met the CDC surveillance case definition with a rash, Bell’s palsy, or arthritis.

These delays are devastating. Patients suffer for nearly two years with untreated infection before diagnosis. During that time, the infection progresses from early localized disease to disseminated and potentially chronic infection. Neurologic complications develop. Cardiac involvement may occur. Quality of life deteriorates.

Critically, 60% of delayed-diagnosis cases had classic CDC-defined presentations: erythema migrans rash, Bell’s palsy, or arthritis. These weren’t obscure, atypical cases. These were textbook Lyme presentations that should have triggered immediate testing and treatment—yet diagnosis was delayed by nearly two years.

In non-endemic regions, if even classic presentations experience two-year diagnostic delays, atypical presentations likely go undiagnosed indefinitely.

Geographic Expansion Matters

This study should serve as a reminder of the need for clinicians to examine patients with a clinical history consistent with Lyme disease to determine if they do have the illness even in areas not considered endemic.

Lyme disease geographic range is expanding. Climate change is extending tick habitat. Migratory birds transport infected ticks to new regions. Human activity—recreational travel, residential development in wooded areas—increases exposure.

North Carolina now has confirmed endemic counties. Virginia has documented geographic expansion with new disease clusters. Yet clinical practice in these regions hasn’t caught up with epidemiologic reality. Clinicians continue operating under outdated geographic assumptions, failing to test patients whose symptoms clearly warrant investigation.

The consequence: patients with Lyme disease in emerging endemic areas go undiagnosed because their location doesn’t match clinicians’ mental maps of where Lyme “should” occur.

Frequently Asked Questions

How many patients with Lyme-consistent symptoms were tested?
Only 18% (297 of 1,621 patients) with clinical history consistent with Lyme disease were tested. The remaining 82% received no testing despite documented symptoms warranting investigation.

What symptoms triggered testing in this non-endemic region?
Classic late-stage presentations: large joint arthritis, cranial nerve palsy (especially Bell’s palsy), meningitis, and cardiac AV block. Even then, only 18% were tested. Atypical presentations likely received no testing at all.

Why weren’t more patients tested?
Geographic bias (North Carolina considered non-endemic), lack of clinician awareness, alternative diagnoses pursued instead, cost concerns, and patient symptom dismissal. The study didn’t examine specific reasons for the 82% testing gap.

What’s the average delay in Lyme diagnosis?
1.8 to 2 years on average. Critically, 60% of delayed cases had classic CDC-defined presentations (EM rash, Bell’s palsy, arthritis) that should have triggered immediate diagnosis—yet still experienced nearly two-year delays.

Should doctors test for Lyme in non-endemic areas?
Yes. Geographic range is expanding. Patients travel to endemic areas. Symptoms consistent with Lyme disease warrant testing regardless of location. The 82% untested rate represents a massive diagnostic failure.

Clinical Takeaway

This Duke University study examining Lyme disease testing patterns in North Carolina reveals a staggering diagnostic gap in non-endemic regions. Between 2005 and 2010, 1,621 patients sought care with clinical history consistent with Lyme disease. Only 297 (18%) were tested. The remaining 82% received no diagnostic testing whatsoever despite documented clinical presentations warranting investigation. The 297 tested patients had classic late-stage Lyme presentations: 110 with large joint arthritis, 98 with cranial nerve palsy, 75 with meningitis, and others with combinations including cardiac AV block. These are textbook Lyme manifestations. Yet only 18% of patients with compatible clinical history triggered testing—even for these obvious presentations. The study’s scope was deliberately narrow, focusing only on conditions “most frequently attributable to Lyme disease.” It completely excluded chronic neurologic Lyme disease, Lyme encephalopathy, neuropsychiatric presentations, and post-treatment Lyme disease syndrome. For these atypical presentations, testing rates in non-endemic settings likely approach zero. The authors didn’t examine why 82% went untested or where patients were subsequently diagnosed. Geographic bias likely plays major role—North Carolina not considered highly endemic leads clinicians to assume Lyme doesn’t occur locally. Lack of awareness prevents recognition of compatible presentations. Alternative diagnoses are pursued—arthritis attributed to rheumatology, Bell’s palsy to viral infection, meningitis to other causes. Testing cost concerns and patient symptom dismissal compound the problem. The consequences are severe. Treatment delays averaging 1.8-2 years have been documented. Patients suffer for nearly two years with untreated infection before diagnosis. During that time, disease progresses from early localized to disseminated and potentially chronic infection. Neurologic complications develop. Quality of life deteriorates. Critically, 60% of delayed-diagnosis cases had classic CDC-defined presentations—EM rash, Bell’s palsy, or arthritis. These weren’t obscure cases. These were textbook Lyme that should have triggered immediate testing and treatment—yet experienced nearly two-year delays. In non-endemic regions, if classic presentations experience two-year delays, atypical presentations likely go undiagnosed indefinitely. Geographic expansion makes this increasingly problematic. North Carolina now has endemic counties. Virginia shows documented expansion. Climate change extends tick habitat. Migratory birds transport infected ticks to new regions. Yet clinical practice hasn’t caught up with epidemiologic reality. Clinicians operate under outdated geographic assumptions, failing to test patients whose symptoms clearly warrant investigation. The clinical imperative is clear: examine patients with clinical history consistent with Lyme disease to determine if they have the illness—even in areas not considered endemic. The 82% untested rate represents massive diagnostic failure. Geographic location should not override clinical judgment when symptoms warrant testing.