The Mite Burrows In and Begins Laying Eggs
A fertilized female mite tunnels into the stratum corneum, short placeholder.
- ~0.4mm: Mite size (barely visible to eye)
- ~2mm/day: Burrow speed (placeholder pace stat)
- 2–3/day: Eggs laid (placeholder over lifetime)
- ~4–6wk: Mite lifespan (on host, placeholder)
Burrow tunnel anatomy
Short placeholder: thin winding track in top skin layer.
Egg and fecal pellet deposition
Short placeholder: eggs and scybala left along the tunnel.
Placeholder highlight: burrow line plus a terminal papule marks active mite.
Larvae Hatch, Mature, and Colonize New Sites
Placeholder lead: eggs hatch into larvae that molt and re-burrow elsewhere.
- ~3–4 days: Hatch time (placeholder incubation)
- 10–15: Typical mite load (placeholder classic scabies)
- webs, wrists: Favored sites (placeholder distribution)
- spared: Face/scalp (adults) (placeholder note)
Larva-to-adult molting
Short placeholder: larva molts through nymph stages to adult.
Typical body distribution
Short placeholder: finger webs, wrists, waistline, elbows favored.
Placeholder highlight: adults usually spare the face and scalp.
Delayed Hypersensitivity to Mite, Egg, and Fecal Proteins
Placeholder lead: itching reflects immune sensitization, not raw mite count.
- 2–6 wk: Onset after exposure (placeholder first infestation)
- 1–2 days: Reinfestation onset (placeholder sensitized host)
- worse at night: Itch pattern (placeholder circadian note)
- allergic reaction: Cause (placeholder not toxin)
Why itching lags infestation
Short placeholder: sensitization takes weeks to develop fully.
Nocturnal itch pattern
Short placeholder: warmth in bed increases mite activity, itch.
Placeholder highlight: itch severity does not track live mite count.
Whole-Body 5% Permethrin Cream, Neck Down
Placeholder lead: full-body coverage is essential, not just visible burrows.
- 5%: Concentration (placeholder permethrin cream)
- 8–14 hr: Contact time (placeholder overnight application)
- neck down: Coverage area (placeholder whole body)
- spot-treating: Common error (placeholder missed sites)
Application protocol
Short placeholder: apply to all skin from neck downward.
The partial-coverage mistake
Short placeholder: treating only visible burrows leaves mites alive.
Placeholder highlight: incomplete coverage is a leading cause of treatment failure.
Mites Die, But Itching Can Persist for Weeks
Placeholder lead: post-scabietic itch is expected and not treatment failure.
- ~24–48 hr: Mite clearance (placeholder full-coverage dose)
- 2–4 wk: Itch persistence (placeholder residual reaction)
- >4–6 wk: Retreat threshold (placeholder new burrows only)
- key step: Patient education (placeholder prevents overtreatment)
Dead mite, live allergy
Short placeholder: residual immune reaction outlives the mites.
When to actually retreat
Short placeholder: new burrows or no improvement after weeks.
Placeholder highlight: itching alone, without new burrows, rarely needs retreatment.