How can borreliosis be detected after a tick bite? - briefly
Serological analysis—initial ELISA screening followed by confirmatory Western blot—conducted 2–4 weeks after the bite, together with PCR of skin biopsy or blood when early manifestations appear, constitutes the primary diagnostic strategy. If the attachment is recent and no symptoms are present, clinicians typically monitor the patient and repeat testing should clinical signs emerge.
How can borreliosis be detected after a tick bite? - in detail
After a tick attachment, the first step in identifying Lyme disease is a careful examination of the bite site. Look for an expanding erythema with central clearing (often called a “bull’s-eye” rash). The lesion typically appears 3–30 days after the bite; its presence strongly suggests early infection.
If the rash is absent, laboratory testing becomes essential. The recommended serological algorithm consists of two stages:
- Screening test: Enzyme‑linked immunosorbent assay (ELISA) or chemiluminescent immunoassay (CLIA) detecting IgM and IgG antibodies against Borrelia burgdorferi antigens. Positive or equivocal results require confirmation.
- Confirmatory test: Western blot analysis distinguishing specific IgM (bands 23‑kDa, 39‑kDa, 41‑kDa) and IgG (bands 18‑kDa, 28‑kDa, 30‑kDa, 39‑kDa, 41‑kDa, 45‑kDa, 58‑kDa, 66‑kDa). Interpretation follows established criteria for early versus late disease.
Molecular methods add sensitivity during the initial phase when antibodies may not yet be detectable. Polymerase chain reaction (PCR) applied to skin biopsy of the rash, joint fluid, or cerebrospinal fluid can identify Borrelia DNA. Positive PCR results are highly specific but have limited sensitivity outside the skin lesion.
Culturing the organism from skin, blood, or cerebrospinal fluid provides definitive proof but requires specialized media (Barbour‑Stoenner‑Kelly) and extended incubation (up to 6 weeks). Because of low yields, culture is rarely used in routine practice.
In patients with neurological or cardiac manifestations, additional investigations are warranted:
- Cerebrospinal fluid analysis: Elevated protein, lymphocytic pleocytosis, and intrathecal synthesis of Borrelia‑specific antibodies support neuroborreliosis.
- Electrocardiography and echocardiography: Detect conduction abnormalities or myocarditis associated with disseminated infection.
Timing influences test selection. Antibody tests are reliable after 3–4 weeks post‑exposure; PCR and skin biopsy are most useful within the first two weeks. Combining clinical assessment with appropriate laboratory techniques yields the most accurate diagnosis.