Cervical Lymphadenopathy in Suspected Lyme Disease

Clinical Diagnosis and Investigation

The Centers for Disease Control and Prevention recommends a two-tiered serologic approach (ELISA/EIA followed by Western immunoblot) for diagnosis of Lyme disease, but clinical diagnosis based on exposure history and accompanying features takes precedence over laboratory testing in endemic areas 1, 2
The diagnosis of Lyme disease is based primarily on clinical findings, and exposure history is the most crucial factor governing pretest probability, as stated by the MMWR Recommendations and Reports 3, 2
Documenting tick exposure history and geographic location is essential, as patients without recent travel to endemic regions have only a 10% positive predictive value for Lyme serology 2
Identifying accompanying Lyme disease features, such as erythema migrans rash (present in 70-80% of cases), fever with sudden onset, chills, headache, myalgia, and arthralgia, is critical for diagnosis 3, 4

The American College of Physicians recommends an initial screening with IgG-EIA and IgM-EIA (or IFA), followed by confirmatory IgG and IgM immunoblot if positive or borderline 1, 5
The sensitivity of serologic testing is only 30-40% in early disease due to the antibody window period, but 70-100% in disseminated disease, according to the Emerging Infectious Diseases journal 6
Ruling out syphilis by performing a T. pallidum hemagglutination assay is necessary to exclude cross-reactivity 1, 5

The Infectious Diseases Society of America notes that tularemia (Francisella tularensis) can cause glandular form (12.5-15.9% of cases), ulceroglandular form (49-75%), associated with tick exposure, sudden fever onset, and pulse-temperature dissociation 4
Kawasaki disease can cause unilateral anterior cervical lymphadenopathy ≥1.5 cm, but requires fever ≥5 days plus ≥4 additional principal criteria (conjunctivitis, oral changes, rash, extremity changes), as stated by the Circulation journal 7

The MMWR Recommendations and Reports warns against relying solely on serology in early disease, as the antibody window period means negative serology does not exclude Lyme disease in the first 2-4 weeks 1, 6
The Emerging Infectious Diseases journal advises against misinterpreting persistent antibodies as active infection, as antibodies persist for months to years after successful treatment and cannot be used as markers of active disease 3, 8, 9

The European Centre for Disease Prevention and Control recommends using ELISA as a first-step screening test, which has high sensitivity 10, 11, 12
The Centers for Disease Control and Prevention suggests that IgG and IgM antibodies can be detected separately using ELISA 10, 13
A positive or borderline ELISA result requires confirmation testing, as recommended by the Clinical Microbiology and Infection journal 10, 11, 14
ELISA can be performed using whole cell lysate or recombinant antigens, according to the Clinical Microbiology and Infection journal 13

In early disease (first 3 weeks), both ELISA and LIA have low sensitivity (30-40%) because the antibody response has not yet developed, as reported in Emerging Infectious Diseases 12
In disseminated disease, sensitivity increases to 70-100%, according to Emerging Infectious Diseases 12
LIA and Western blot have high specificity (>98%) and minimize cross-reactions, as stated in Emerging Infectious Diseases 12
ELISA alone has a risk of cross-reaction with Treponema pallidum and other pathogens, as noted in Clinical Microbiology and Infection 10, 11, 13

The first step involves screening with IgG-ELISA and IgM-ELISA, as recommended by Clinical Microbiology and Infection 10, 11, 14
The second step involves confirmation with IgG and IgM immunoblot (or LIA) for positive or borderline results, as suggested by Clinical Microbiology and Infection and Emerging Infectious Diseases 10, 11, 12

For disease duration <6-8 weeks, both IgM and IgG immunoblot are valid, according to Emerging Infectious Diseases 12
For disease duration >6-8 weeks, only IgG immunoblot is clinically interpretable, as reported in Emerging Infectious Diseases 12
IgG positivity requires ≥5/10 specific bands, and IgM positivity requires ≥2/3 specific bands, as stated in Emerging Infectious Diseases 12