What is
Lyme disease?

Understanding Lyme disease

Lyme disease is an infectious disease caused by spirochetal bacteria of the genus Borrelia, most commonly Borrelia burgdorferi in North America and Borrelia afzelii and Borrelia garinii in Europe. It is the most common vector-borne disease in the Northern Hemisphere, with an estimated 476,000 cases diagnosed annually in the United States alone and approximately 200,000 in Europe.

The disease is named after the town of Old Lyme, Connecticut, where a cluster of cases was first identified in the 1970s. The causative bacterium was isolated by Willy Burgdorfer in 1982. Despite being recognized for over four decades, Lyme disease remains one of the most misunderstood and underdiagnosed infections in medicine.

At Klinik St. Georg's dedicated Lyme disease center, we have been treating Lyme patients since 1994. What we have learned in that time is that this disease is more complex, more varied in its presentation, and more challenging to treat than most standard medical textbooks acknowledge.

How Lyme disease is transmitted

Lyme disease is transmitted primarily through the bite of infected ticks of the genus Ixodes. In Europe, the primary vector is Ixodes ricinus (the castor bean tick or sheep tick). In North America, it is Ixodes scapularis (the blacklegged tick or deer tick) in the eastern and midwestern states and Ixodes pacificus on the West Coast.

The ticks acquire the Borrelia bacteria by feeding on infected animal reservoirs — primarily small mammals like white-footed mice, as well as birds and lizards. When an infected tick subsequently feeds on a human, the bacteria can be transmitted through the tick's saliva into the skin.

Key facts about transmission

• Tick attachment time matters. The traditional teaching is that a tick must be attached for 36–48 hours to transmit the infection. However, recent research has demonstrated that transmission can occur in less than 24 hours, particularly with European Borrelia species. Any tick bite with any duration of attachment carries some risk.
• Many patients never see the tick. Nymphal ticks (the juvenile stage) are extremely small — roughly the size of a poppy seed. Studies suggest that 50–70% of patients with confirmed Lyme disease have no recollection of a tick bite.
• Not all tick bites cause the rash. The erythema migrans (EM) rash — the classic "bull's-eye" — is considered the hallmark of early Lyme disease, but it occurs in only an estimated 70–80% of cases. Its absence does not rule out infection.
• Geography is expanding. Climate change is driving tick populations into new territories. Regions that were previously considered low-risk — including northern Europe, Canada, and higher altitudes — are now reporting increasing Lyme disease incidence.

Stages of Lyme disease

Lyme disease is conventionally described in three stages, though the progression is not always linear and stages can overlap.

Stage 1: Early localized infection (days to weeks)

The earliest stage occurs at the site of the tick bite. The hallmark is the erythema migrans rash, which typically appears 3–30 days after the bite and expands over days. Accompanying symptoms may include fatigue, headache, mild fever, muscle aches, and joint pain. At this stage, the infection is generally localized to the skin and can often be effectively treated with oral antibiotics.

Stage 2: Early disseminated infection (weeks to months)

If untreated, Borrelia can spread through the bloodstream to other parts of the body. This stage may present with multiple erythema migrans lesions, neurological involvement (facial palsy, meningitis, radiculopathy), cardiac involvement (Lyme carditis, heart block), and worsening systemic symptoms including fatigue, cognitive difficulties, and musculoskeletal pain.

Stage 3: Late disseminated infection (months to years)

Late-stage Lyme disease can develop months or even years after the initial infection, particularly if the earlier stages were untreated or inadequately treated. Manifestations include chronic arthritis (particularly in the large joints), chronic neurological symptoms (encephalopathy, neuropathy, cognitive impairment), and persistent fatigue. This is the stage at which most of our patients present to us — often after years of undiagnosed or undertreated disease.

Symptoms of Lyme disease

Lyme disease is sometimes called "the great imitator" because its symptoms can mimic dozens of other conditions. This is one of the primary reasons it is so frequently misdiagnosed.

Common symptoms include:

• Neurological: Brain fog, cognitive impairment, memory problems, difficulty concentrating, word-finding difficulties, headaches, dizziness, neuropathy (tingling, numbness, burning), facial palsy, light and sound sensitivity
• Musculoskeletal: Migratory joint pain, arthritis, muscle pain, neck stiffness, jaw pain
• Fatigue: Profound exhaustion unrelieved by rest, post-exertional malaise, exercise intolerance
• Cardiovascular: Palpitations, chest pain, shortness of breath, heart block, tachycardia
• Sleep: Insomnia, unrefreshing sleep, disrupted circadian rhythm, night sweats
• Psychiatric: Depression, anxiety, irritability, depersonalization, mood swings
• Dermatological: Erythema migrans rash, acrodermatitis chronica atrophicans (late-stage skin changes)

For detailed information on individual symptoms, visit our symptom guide.

The testing challenge

One of the most frustrating aspects of Lyme disease for patients is the unreliability of standard testing. The standard diagnostic approach in most countries is the two-tier testing system: an initial ELISA (enzyme-linked immunosorbent assay) followed by a Western blot if the ELISA is positive or equivocal.

Why standard testing fails

• Sensitivity gaps. The two-tier system has a sensitivity of approximately 30–40% in early Lyme disease and 60–85% in later stages. This means that a significant proportion of infected patients will receive negative results.
• Antibody-dependent detection. Standard tests detect antibodies against Borrelia, not the bacteria themselves. Patients with suppressed immune function, early infection (before antibodies develop), or certain antibiotic exposure may not produce detectable antibody levels.
• Strain variation. The standard tests were developed primarily against North American Borrelia burgdorferi strains. European Borrelia species (B. afzelii, B. garinii) may not be adequately detected.
• Interpretation subjectivity. Western blot interpretation involves reading band patterns, which can vary between laboratories and technicians.

This is why clinical diagnosis — a careful evaluation of symptoms, history, exposure risk, and treatment response — remains essential. A negative test does not rule out Lyme disease. A thorough clinician knows this.

The treatment landscape

Standard treatment for early Lyme disease is a 2–4 week course of oral antibiotics, typically doxycycline, amoxicillin, or cefuroxime. For early-stage disease caught promptly, this approach is often effective.

The challenge arises when treatment fails or when the disease is diagnosed late. The medical community is divided on how to approach patients who remain symptomatic after standard antibiotic therapy. The mainstream position — held by organizations like the IDSA (Infectious Diseases Society of America) — is that persistent symptoms represent a "post-treatment Lyme disease syndrome" (PTLDS) and that further antibiotics are not warranted. The clinical position — held by organizations like ILADS (International Lyme and Associated Diseases Society) and supported by a growing body of research — is that persistent infection can occur and may require extended or alternative treatment approaches.

Treatment approaches

• Standard antibiotics: The first-line approach for early-stage Lyme disease. Effective when the infection is caught early.
• Extended antibiotics: Longer courses or combination antibiotic regimens for patients who do not respond to standard therapy.
• Whole-body hyperthermia: Controlled fever therapy that raises core body temperature to ranges where Borrelia becomes structurally vulnerable. Our primary treatment modality, with over 30,000 sessions performed.
• Integrative protocols: Multi-modal treatment combining hyperthermia, antimicrobials, immune support, apheresis, and nutritional therapy.

For a complete overview of treatment options, visit our treatment options page.

When Lyme disease persists

For a meaningful proportion of patients, Lyme disease does not resolve with standard treatment. Estimates vary, but research suggests that 10–20% of patients treated with standard antibiotics continue to experience significant symptoms months or years after treatment.

The reasons for persistent disease are likely multifactorial:

• Bacterial persistence: Research has demonstrated that Borrelia can survive antibiotic treatment in animal models by forming dormant "persister" cells, sequestering in biofilms, and hiding in tissues with limited antibiotic penetration.
• Immune dysregulation: Chronic infection can trigger lasting changes in immune function that perpetuate inflammation even after the bacterial burden is reduced.
• Co-infections: Many patients with Lyme disease are co-infected with other tick-borne pathogens (Babesia, Bartonella, Ehrlichia) that require different treatment approaches.
• Tissue damage: Prolonged infection can cause structural damage to the nervous system, joints, and other tissues that requires additional time and support to heal.

For a deeper exploration of this topic, read our guide on chronic Lyme disease.

What to do if you suspect Lyme disease

If you are reading this guide because you suspect Lyme disease may be behind your symptoms, here is what we recommend:

1. Document your symptoms. Write down everything you are experiencing — when it started, how it has changed, and what makes it better or worse. Bring this to every medical appointment.
2. Review your exposure history. Think about possible tick exposure, even if you do not remember a bite. Where have you lived, traveled, and spent time outdoors?
3. Seek specialized evaluation. If standard testing and treatment have not resolved your symptoms, consider consulting a physician with specific experience in Lyme disease. General practitioners and infectious disease specialists without Lyme-specific training may not be equipped to evaluate complex cases.
4. Educate yourself. Understanding your condition is empowering. Read our knowledge base, our symptom guides, and our treatment comparisons.
5. Reach out to us. If you would like a physician at Klinik St. Georg to review your case, you can share your story here. There is no cost, no obligation, and a real doctor reads every inquiry.

If you have been searching for answers and feeling dismissed, we want you to know: your symptoms are real, your frustration is valid, and you deserve a medical team that takes you seriously. That is what we are here for.