Latent Reservoir in the Dorsal Root Ganglion
Placeholder: VZV hides quietly inside sensory neuron cell bodies for decades.
- DRG: Latency site (Placeholder short note)
- Episomal: Genome form (Placeholder short note)
- Minimal: Gene expression (Placeholder short note)
- Decades: Duration (Placeholder short note)
Establishing latency
Placeholder: primary varicella seeds ganglia via retrograde axonal transport.
Immune containment
Placeholder: resident T-cells keep the latent virus permanently suppressed.
Placeholder key insight: latency is stable while surveillance stays strong.
Age-Related Decline of Systemic Immunity
Placeholder: aging thymic output and immune diversity shrink over time.
- ↓ with age: Thymic output (Placeholder short note)
- Declining: Naive T-cells (Placeholder short note)
- ~50yrs: Risk onset (Placeholder short note)
- >60yrs: Peak incidence (Placeholder short note)
Immunosenescence drivers
Placeholder: thymic involution reduces new antigen-specific T-cell supply.
Population risk curve
Placeholder: shingles incidence rises steadily after age fifty.
Placeholder key insight: age is the strongest single risk factor.
Loss of VZV-Specific Cell-Mediated Immunity
Placeholder: VZV-specific T-cell clones shrink and lose potency.
- ↓ decades: VZV-CMI (Placeholder short note)
- Reduced: Boosting (Placeholder short note)
- Stable: Antibody titer (Placeholder short note)
- T-cells: Key defense (Placeholder short note)
Why T-cells matter most
Placeholder: antibodies alone cannot control intracellular latent virus.
Threshold for control
Placeholder: below a critical CMI level, suppression fails.
Placeholder key insight: CMI decline, not antibody loss, drives shingles.
Viral Reactivation and Anterograde Axonal Transport
Placeholder: unchecked virus replicates and travels down the axon.
- Anterograde: Transport (Placeholder short note)
- Sensory nerve: Site (Placeholder short note)
- Neuralgia: Symptom (Placeholder short note)
- Days: Onset (Placeholder short note)
Reactivation trigger
Placeholder: weakened surveillance allows lytic gene expression to resume.
Axonal spread
Placeholder: virions move along the nerve toward the skin.
Placeholder key insight: pain often precedes visible rash by days.
Dermatome-Confined Vesicular Eruption
Placeholder: rash appears strictly within one sensory dermatome band.
- Unilateral: Pattern (Placeholder short note)
- 1 dermatome: Distribution (Placeholder short note)
- Vesicles: Lesion type (Placeholder short note)
- PHN risk: Complication (Placeholder short note)
Dermatomal confinement
Placeholder: rash follows the single ganglion nerve's skin territory.
Clinical course
Placeholder: vesicles crust over one to two weeks typically.
Placeholder key insight: postherpetic neuralgia risk rises steeply with age.