Lyme Disease Diagnosis and Treatment

Clinical Manifestations

Erythema migrans (EM) is a characteristic skin lesion, typically >5 cm in diameter, occurring in 70-80% of infected individuals, often accompanied by fever, lymphadenopathy, myalgias, and arthralgias 1, 2
Neurologic involvement can manifest as facial nerve palsy, meningitis, and meningo-radiculitis, while cardiac involvement occurs in 5% of cases, with manifestations including atrioventricular block and myocarditis 1, 2
Arthritis is characterized by recurrent large-joint arthritis, especially of the knee, and acrodermatitis chronica atrophicans (ACA) is a bluish-red discoloration progressing to skin atrophy, associated with B. afzelii 1, 2, 3
Late neurologic manifestations can include peripheral neuropathy, encephalopathy, and encephalomyelitis 2, 3

Clinical diagnosis can be made based on EM rash in endemic areas, without laboratory testing, as recommended by the American College of Rheumatology 2, 4
Two-tiered serologic testing with ELISA/IFA followed by Western immunoblot can provide sensitivity of 70-100% and specificity >95%, with the American College of Rheumatology recommending this approach for Lyme disease diagnosis 2, 5
Synovial fluid analysis in arthritis cases shows mild-to-moderate inflammation, and PCR of synovial fluid may provide additional diagnostic certainty in seropositive patients 3

First-line oral antibiotics for Lyme disease include doxycycline, amoxicillin, and cefuroxime axetil, with recommended dosing as follows:

Antibiotic	Adult Dosage	Child Dosage
Doxycycline	100 mg twice daily for 10 days	4 mg/kg/day in 2 divided doses (maximum 100 mg per dose) for children ≥8 years
Amoxicillin	500 mg three times daily for 14 days	50 mg/kg/day in 3 divided doses (maximum 500 mg per dose)
Cefuroxime axetil	500 mg twice daily for 14 days	30 mg/kg/day in 2 divided doses (maximum 500 mg per dose) [3, 5]

Second-line treatment is azithromycin for patients who are unable to take doxycycline and beta-lactams, and for CNS involvement, IV antibiotics are preferred, with options including ceftriaxone, cefotaxime, or penicillin G for 14-21 days 5

The following antibiotic treatment options are recommended for specific manifestations:

Manifestation	Treatment
Meningitis or radiculopathy	IV ceftriaxone 2g daily for 14 days (range 10-28 days)
Facial nerve palsy without CSF abnormalities	Oral regimen as for erythema migrans for 14 days
Facial nerve palsy with CSF abnormalities	Treatment as for meningitis
Arthritis that has failed to improve or worsened	IV ceftriaxone 2g daily for 2-4 weeks [6, 3]

Patients with heart block due to Lyme disease should receive parenteral antibiotics, specifically intravenous ceftriaxone, with hospitalization and cardiac monitoring for symptomatic patients or those with advanced heart block, as recommended by the IDSA and ACR 3, 5
The IDSA, AAN, and ACR do not recognize "chronic Lyme disease" as a valid medical diagnosis, and support a symptom-specific approach for post-Lyme disease syndrome management, with a strong recommendation against further antibiotics for patients without objective evidence of infection 6, 5, 3
Symptomatic management, including non-steroidal anti-inflammatory drugs (NSAIDs), physical therapy, cognitive behavioral therapy for pain management, graded exercise programs, and consideration of referral to a pain management specialist, is recommended for post-Lyme disease syndrome 5

Prophylaxis is recommended only for high-risk tick bites meeting specific criteria, including identified Ixodes spp. vector tick, tick attached for ≥36 hours, prophylaxis started within 72 hours of tick removal, and local infection rate of ticks with B. burgdorferi ≥20%, as recommended by the IDSA and ACR 3, 5
The prophylactic regimen includes a single dose of doxycycline, with 200 mg for adults and 4.4 mg/kg (maximum 200 mg) for children ≥8 years, as recommended by the ACR 5