Undiagnosed Lyme Disease: How It Happens and Why
Symptoms are often fragmented across specialties
Testing limitations and missed exposure histories can delay diagnosis
Earlier recognition may change treatment pathways
Undiagnosed Lyme disease can occur when symptoms are overlooked, testing is incomplete, or Lyme disease is never considered despite exposure risk and compatible symptoms.
Just a couple of weeks ago, I had a new patient on my schedule—someone who specifically requested a consultation for Lyme disease.
This reflection is written for clinicians—not as criticism, but as a reminder of how easily diagnostic momentum can replace diagnostic curiosity.
Before the visit, I reviewed her chart, expecting to see at least some evaluation for tick-borne illness.
She had already seen multiple specialists, including rheumatology, neurology, and infectious disease. Her records documented a long list of symptoms: fatigue, cognitive slowing, joint pain, palpitations, headaches, and what she described as air hunger.
But one thing stood out immediately.
There was no Lyme disease evaluation.
No Western blot. No co-infection testing. No documentation that tick-borne illness had even been considered. Testing limitations and timing can complicate diagnosis, which I review in Lyme test accuracy.
She lived in a high-risk area. She spent time outdoors. Her symptoms followed a recognizable post-infectious pattern. And yet Lyme disease was not on the differential.
This is how undiagnosed Lyme disease often begins—not with overt denial, but with omission. I discuss this pattern in greater depth in medical dismissal in chronic Lyme disease.
Why Lyme disease is sometimes never considered
When she arrived, she described a slow, progressive decline that began nearly a year earlier after a summer hike.
She did not recall a tick bite. She never noticed a rash.
Many patients with undiagnosed Lyme disease do not remember a tick bite or recognize an early rash, which can delay consideration of tick-borne illness.
But she developed a flu-like illness followed by symptoms that never fully resolved.
Over time, her condition worsened.
Patients with untreated or unrecognized Lyme disease may experience symptoms that evolve gradually, making pattern recognition more difficult over time.
She had been treated for anxiety. Prescribed medications for sleep and inflammation. Evaluated for autoimmune disease and neurologic conditions, including lupus and multiple sclerosis.
Each assessment ruled something out—but nothing integrated the full clinical picture.
This pattern is not rare. It reflects a broader issue in complex illness care: once a syndromic diagnosis is applied, further etiologic inquiry may quietly stop.
Patients who ask whether they can have Lyme disease and not know it often describe this exact pattern of fragmented evaluation and delayed synthesis.
Diagnoses that describe patterns, not causes
In many clinical settings, when an otherwise healthy patient—often a young woman—presents with persistent fatigue and multisystem symptoms, the initial response is sometimes to apply a diagnosis that describes a pattern rather than continue searching for a driver.
Common considerations include fibromyalgia, mast cell activation syndrome, POTS, ME/CFS, hypermobility syndromes, mold-related illness, gastrointestinal dysbiosis, hormonal imbalance, histamine intolerance, long COVID, or stress-related explanations such as burnout or trauma.
Each of these diagnoses has a legitimate clinical basis. The concern is not their use, but their use in isolation—without continued etiologic inquiry.
These syndromic diagnoses often emerge after an inciting event—frequently an infection—but the inciting cause may no longer be revisited once a label is applied.
This is how undiagnosed Lyme disease becomes entrenched.
For patients with overlapping autonomic complaints, fatigue, and neurologic symptoms, see autonomic dysfunction in Lyme disease.
Recognizing symptoms of undiagnosed Lyme disease
We returned to first principles.
I took a detailed exposure history, mapped symptom evolution over time, and looked for coherence across systems rather than isolated complaints.
Based on the full clinical picture, I ordered what should have been considered much earlier:
- Lyme disease IgM and IgG Western blot
- Babesia and Bartonella testing
- Repeat inflammatory and hematologic markers
This was not guesswork.
Lyme disease remains a clinical diagnosis, guided by exposure risk, symptom trajectory, and pattern recognition—not algorithms alone.
Diagnostic challenges become greater when symptoms overlap with conditions discussed in persistent Lyme disease mechanisms.
Patients frequently search for undiagnosed Lyme disease symptoms years later, especially when earlier testing was limited, symptoms evolved slowly, or Lyme disease testing was never performed during the early stages of illness.
The results—and a turning point
Her results were revealing.
Her Lyme IgG Western blot was positive, with six of ten bands.
She also tested positive for Babesia duncani IgG.
She did not have Lyme disease alone.
She had a co-infection requiring a different treatment approach.
This explained why the brief course of doxycycline she had received months earlier had not altered her trajectory.
Babesia does not respond to doxycycline.
Treatment was adjusted accordingly.
For the first time in months, there was a coherent plan.
For patients with air hunger, night sweats, and treatment-resistant symptoms, Babesia is frequently overlooked. I review this in more detail in Babesia air hunger and treatment considerations.
Why undiagnosed Lyme disease keeps happening
This was not an outlier.
Patients with Lyme disease and co-infections frequently move through fragmented systems of care, accumulating diagnoses without integration.
Symptoms are managed piecemeal. Testing is delayed or incomplete. Responsibility for synthesis falls through the cracks.
Premature diagnostic closure is rarely intentional.
It usually emerges from time pressure, guideline anchoring, and discomfort with diagnostic uncertainty.
Undiagnosed Lyme disease is rarely the result of a single error; it more often reflects diagnostic closure that unfolds over time.
I explore this complexity further in why some patients do not improve after Lyme treatment.
Public health agencies acknowledge that symptoms may persist after treatment, including guidance from the CDC.
How to avoid missed or delayed Lyme disease diagnosis
Lyme disease requires more than pattern recognition—it requires curiosity, reassessment, and restraint from closing the diagnostic process too early.
Preventing undiagnosed Lyme disease requires a willingness to revisit assumptions and re-evaluate what may have been overlooked.
Understanding the full range of Lyme disease treatment options can also help clinicians and patients navigate what comes next.
This patient did not need reassurance that her tests were normal.
She needed someone to ask what had not yet been tested.
This is not about rejecting established diagnoses.
It is about remembering that diagnoses should guide inquiry—not replace it.
Frequently Asked Questions
How common is undiagnosed Lyme disease?
Undiagnosed Lyme disease is common when symptoms are nonspecific, exposure history is missed, or Lyme disease is not included in the differential diagnosis.
Can Lyme disease go undetected for years?
Yes. Some patients report symptoms for years before Lyme disease testing or tick-borne illness evaluation is considered, particularly when symptoms overlap with other conditions.
What is Lyme disease commonly mistaken for?
Lyme disease is frequently mistaken for fibromyalgia, chronic fatigue syndrome, anxiety disorders, autoimmune disease, POTS, neurologic conditions, or other syndromic diagnoses.
Can you have Lyme disease and not know it?
Some individuals do not recall a tick bite or rash and may initially experience nonspecific symptoms, making recognition more difficult.
How do you test for undiagnosed Lyme disease?
Testing often begins with exposure history, symptom review, and Lyme disease testing, but interpretation depends on timing, symptoms, and whether coinfections are considered.
Clinical Takeaway
Undiagnosed Lyme disease often develops through a series of small missed opportunities rather than one obvious mistake.
Exposure history, symptom evolution, and diagnostic reassessment remain important when symptoms span multiple systems.
The challenge is often not recognizing a rare disease—it is recognizing when the diagnostic process stopped too soon.
Related Articles
Lyme disease symptoms guide
Persistent Lyme disease mechanisms
Lyme test accuracy
Tick-borne coinfections
References
- Centers for Disease Control and Prevention. Post-treatment Lyme disease syndrome. CDC. 2024.
- Schoen RT. A case revealing the natural history of untreated Lyme disease. Nat Rev Rheumatol. 2011;7(3):179-184.
- Kobayashi T, Higgins Y, Melia MT, Auwaerter PG. Mistaken identity: many diagnoses are frequently misattributed to Lyme disease. Am J Med. 2022;135(4):503-511.e5.
- Mazori DR, Orme CM, Mir A, Meehan SA, Neimann AL. Vesicular erythema migrans: an atypical and easily misdiagnosed form of Lyme disease. Dermatol Online J. 2015;21(8).
- Gülbezer EE, Usta O, Güllü D, et al. Misdiagnosed Lyme: A multidisciplinary case series from a non-endemic region. Balkan Med J. 2025;42(6):574-576.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
