What do antibody tests for ticks show? - briefly
Antibody assays detect immune proteins produced against tick‑borne pathogens, indicating prior exposure or infection. A positive result implies the subject has encountered organisms such as Borrelia, Anaplasma or Ehrlichia.
What do antibody tests for ticks show? - in detail
Antibody testing for tick-borne pathogens detects host immunoglobulins that have formed in response to infection. The assay measures specific IgM, which appears within 1–3 weeks after exposure and indicates recent infection, and IgG, which persists for months to years and reflects past exposure or ongoing infection. Results are reported as positive, negative, or equivocal, often with a quantitative titer that helps assess the strength of the immune response.
Interpretation depends on the timing of specimen collection. Early samples may lack detectable antibodies, leading to false‑negative results; repeat testing after 2–3 weeks can capture seroconversion. A rising IgG titer in paired acute and convalescent sera confirms active disease, whereas a stable high IgG level suggests prior exposure without current illness.
Common tick-borne agents evaluated by serology include Borrelia burgdorferi (Lyme disease), Anaplasma phagocytophilum (anaplasmosis), Ehrlichia chaffeensis (ehrlichiosis), Rickettsia spp. (spotted fever group), and Babesia spp. (babesiosis). Each pathogen has dedicated antigen panels; cross‑reactivity between related organisms can produce ambiguous results, requiring confirmatory testing such as Western blot or PCR.
Limitations of antibody assays encompass delayed seroconversion, persistence of IgG after successful treatment, and potential false positives from previous vaccinations or unrelated infections. Laboratories mitigate these issues by using standardized cutoff values, quality‑controlled reagents, and, when necessary, adjunct molecular methods to verify active infection.
Clinicians combine serologic data with clinical presentation, exposure history, and, if available, direct detection techniques to arrive at a definitive diagnosis and guide therapy.