Does Borrelia VlsE IgG indicate past exposure rather than active Lyme infection?

At age 50, the interpretation is the same as for adults generally: Borrelia VlsE IgG is an exposure-associated antibody marker, not an independent measure of current infection.

Clinical evidence

• VlsE/C6 IgG commonly develops after Borrelia burgdorferi infection. In prospective erythema-migrans cohorts, approximately one-third of patients were seroreactive at acute presentation and nearly two-thirds by 3–4 weeks.
• Its presence can be long-lived. After successful treatment, VlsE IgG remained detectable 8–15 years later in 50% of those treated for early disease and 83% of those treated for late disease.
• Therefore, a positive isolated VlsE IgG result is compatible with either current infection or a remote, resolved infection. It cannot establish infection timing, organism viability, or whether current symptoms are due to Lyme disease.

Mechanistic and practical interpretation

• VlsE-directed IgG reflects acquired humoral immune recognition following infection. Persistent antibodies are compatible with immunologic memory and/or sustained antibody production; they are not evidence by themselves of persisting spirochetes.
• Antibody kinetics vary with disease stage, assay format, and early treatment. A negative result early in illness does not reliably exclude recent infection.
• VlsE IgG is not a reliable treatment-response marker: some treated patients become seronegative within months, whereas others remain positive for years.

Clinical implications

• Interpretation should incorporate compatible symptoms, exposure history, illness timing, and validated conventional or modified two-tier serology rather than VlsE IgG alone.
• In someone with prior or possible prior Lyme disease and new symptoms, persistent seropositivity should not be used alone to diagnose active infection or to guide repeat treatment.

Bottom line

• The claim is well supported: VlsE IgG indicates immune recognition after Borrelia exposure and may persist for many years, but alone cannot distinguish active Lyme infection from prior resolved infection or monitor treatment success.