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derm.scabies.core.v1PRODUCTION
derm.scabies.core.v1

Scabies — classic & crusted (Norwegian)

dermatologyacutesubacuteadultpediatric
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12/12 authored

Canonical 12-phase frame with authored status for this dossier.

Current phase

Frame

Detailed

Frame as a Sarcoptes scabiei infestation with an IMMUNOLOGIC (delayed type-IV) itch that lags infestation by weeks — so itch timing, post-scabetic persistence, and "the whole household + the environment, not just the patient" define management. The great-imitator trap (missed as steroid-worsened eczema) and the classic-vs-crusted split (hyperinfestation, outbreak, sepsis) are set here.

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scabies frame set; classic-vs-crusted + great-imitator + contact/public-health escape routes noted

Patient inputs (15)

Web-space/wrist/axilla/periumbilical/genital burrows + papules support IACS clinical/confirmed levels; scalp/face involvement reframes toward infant/elderly/crusted disease (2020 IACS criteria PMID 32034956; community validation PMID 33017426)

Affected household/sexual/close contacts and institutional residence (aged-care, shelter, prison) raise the pre-test probability strongly and trigger the contact-tracing + outbreak arc (European guideline PMID 28639722; WHO framework PMID 34473725)

HIV / HTLV-1 / haematologic / iatrogenic immunosuppression / elderly / neurologic-cognitive impairment predicts crusted scabies (hyperinfestation), the distinct intensive regimen, and outbreak risk (Hasan PLoS NTD 2020 PMID 33338053; European guideline PMID 28639722)

Generalised nocturnal itch out of proportion to visible rash, with the characteristic onset lag (~3-6 wk primary; days on re-infestation), is the central symptom and shapes the pre/post-treatment itch-trajectory counselling (2020 IACS criteria PMID 32034956)

Apparent "treatment failure" is usually post-scabetic itch, re-infestation from untreated contacts, or mis-application — true persistence/resistance is a diagnosis of exclusion (2024 treatment-failure meta-analysis PMID 37625798)

Honey-crust / pustules / impetiginisation → Staphylococcus aureus / Streptococcus pyogenes secondary infection; in endemic settings carries post-streptococcal GN / rheumatic-fever sequelae and crusted-scabies sepsis risk (MDA-impetigo trial PMID 35345391; Hasan PMID 33338053)

Neonates/infants <2 mo → precipitated sulfur (permethrin/ivermectin cautioned); ivermectin generally avoided if weight <15 kg; scalp/face must be treated in infants and the elderly; weight-based ivermectin dosing (European guideline PMID 28639722; WHO control PMID 31178154)

ALL close/household/sexual contacts (even asymptomatic) must be treated simultaneously with a 2-month partner look-back, or re-infestation is near-certain (European guideline PMID 28639722)

High-prevalence/endemic or institutional-outbreak context shifts management toward ivermectin mass drug administration and post-streptococcal-sequelae vigilance (WHO control PMID 31178154; WHO framework PMID 34473725; MDA trial PMID 26650152)

Dermoscopy ("delta-wing-jet"/burrow sign) or skin-scraping/ink-burrow microscopy moves the diagnosis from IACS suspected/clinical to confirmed; microscopy is specific but insensitive in classic disease (2020 IACS PMID 32034956; microscopy/PCR PMID 32255795)

Eosinophilia + markedly raised IgE are common in crusted scabies and support hyperinfestation; CBC also screens for secondary bacterial sepsis (Hasan PLoS NTD 2020 PMID 33338053)

CRP/inflammatory markers track secondary bacterial superinfection / crusted-scabies sepsis severity (Hasan PLoS NTD 2020 PMID 33338053)

Crusted-scabies grade (distribution/crust thickness/prior episodes — Grade 1/2/3) drives the number of ivermectin doses (3 vs 5 vs 7) and isolation intensity (Hasan PLoS NTD 2020 PMID 33338053 — schema-blocked grading captured narratively)

Permethrin or precipitated sulfur preferred in pregnancy/lactation; oral ivermectin generally avoided — gates the scabicide ladder (European guideline PMID 28639722)

Renal function (race-free CKD-EPI 2021) where comorbid CKD/dialysis informs supportive dosing in crusted-scabies inpatients (Hasan PLoS NTD 2020 PMID 33338053 — 23% on dialysis; Inker NEJM 2021)

* = hard-required. Engine cannot meaningfully run until these are filled.

Severity triggers (7)

7 need judgement
  • informationallife_threateningsecondary_bacterial_sepsis_from_impetiginised_crusted_scabies
    Impetiginised / crusted scabies with systemic toxicity, bacteraemia, or rapidly worsening secondary infection
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverecrusted_norwegian_scabies_hyperinfestation
    Hyperkeratotic, crusted, scaly plaques (± reduced/absent itch) in an immunocompromised / HIV / HTLV-1 / elderly / institutionalised / neurologic host — thousands–millions of mites, extremely contagious
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereinstitutional_or_endemic_outbreak_cluster
    Cluster of cases in an aged-care facility / shelter / prison / household network or a high-prevalence endemic community
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderateimmunocompromised_host_crusted_risk
    HIV / HTLV-1 / haematologic malignancy / iatrogenic immunosuppression / advanced age / neurologic-cognitive impairment with scabies
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatepost_streptococcal_sequelae_after_secondary_impetigo
    Secondary S. pyogenes impetigo on scabies in an endemic/resource-limited setting
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatetreatment_failure_or_resistance_pattern
    Persistent active infestation (new burrows/lesions, contacts re-affected) after an adequate scabicide course with contacts treated
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmildpost_scabetic_pruritus_reassurance_not_escalation
    Residual generalised itch persisting up to 2-4 wk after an adequate scabicide course with all contacts treated and no new lesions/burrows
    Trigger could not be auto-evaluated — needs clinician judgement.

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Recommended regimen

Scabies — stepwise scabicide ladder + contact & environmental control (2020 IACS / European 2017 / WHO NTD)
axis: scabies_stepwise_scabicide_ladderstep 1 - Step 1 — First-line topical: permethrin 5% (whole-body, REPEAT day 7-14)
Selected step "Step 1 — First-line topical: permethrin 5% (whole-body, REPEAT day 7-14)" — Classic scabies, any age ≥2 mo; first-line in pregnancy/lactation; applied neck-down (plus scalp/face in infants, the elderly, and crusted disease)
  • permethrin
    first line
    topical_pyrethroid_scabicide
    5% cream, whole body (neck-down; include scalp/face in infants/elderly/crusted) • topical • overnight 8-14 h then wash off; REPEAT on day 7-14 (max: single whole-body application per dose)
    triggers: classic_scabies, pregnancy_or_lactation, age_under_15kg_or_neonate_caution
    European guideline (PMID 28639722) + 2020 IACS (PMID 32034956) first-line topical; Cochrane 2018 (PMID 29608022) ~65-74% wk1-2 clearance, 1-3 applications ~93%; the mandatory day-7-14 repeat covers eggs surviving the first dose.
    rxcui 33199
  • treat_all_close_household_sexual_contacts_simultaneously
    first line
    public_health_intervention
    triggers: any_confirmed_or_clinical_scabies
    European guideline (PMID 28639722) — ALL close/household/sexual contacts treated at the same time (even if asymptomatic), 2-month partner look-back; untreated contacts are the dominant re-infestation driver (2024 failure meta-analysis PMID 37625798).
  • environmental_decontamination_hotwash_seal_bag
    first line
    public_health_intervention
    triggers: any_confirmed_or_clinical_scabies
    European guideline (PMID 28639722) — hot-wash (≥50 °C) + hot tumble-dry, or seal in a plastic bag ≥72 h, all clothing/bedding/towels used in the prior 3-4 days; the off-host mite survives only ~24-36 h, days longer in crusted disease.

outpatient playbook — drug actions (4)

  1. 1. permethrin 5% (whole-body, repeat day 7-14)
    rxcui 33199
    5% cream • topical • overnight then repeat d7-14
    trigger: Classic scabies, any age ≥2 mo incl. pregnancy (European guideline PMID 28639722)
    First-line topical; mandatory repeat covers surviving eggs (Cochrane 2018 PMID 29608022)
  2. 2. oral ivermectin 200 mcg/kg (day 1 + day 8)
    rxcui 6069
    200 mcg/kg • PO • d1 + d8
    trigger: Topical impractical/failed, extensive disease, outbreak (NOT pregnancy or <15 kg) (European guideline PMID 28639722)
    2-dose ivermectin failure 7.1% vs single 15.2% (Mbuagbaw 2024 PMID 37625798)
  3. 3. precipitated sulfur 5-10% (neonates <2 mo, pregnancy)
    rxcui 10223
    5-10% in petrolatum • topical • daily x3
    trigger: Infant <2 mo or pregnancy when permethrin unsuitable (European guideline PMID 28639722)
    Preferred safe option at the extremes of the age/pregnancy spectrum
  4. 4. hydroxyzine + topical steroid (post-scabetic itch)
    rxcui 5553
    25 mg nocte • PO • PRN 2-4 wk
    trigger: Residual itch after adequate treatment + treated contacts (2020 IACS PMID 32034956)
    Post-scabetic hypersensitivity is expected — treat symptomatically, do NOT re-treat with scabicide

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Intense, generalised, nocturnally-worse pruritus (delayed type-IV hypersensitivity to the mite — onset ~3-6 wk in primary infestation, days on re-infestation) (2020 IACS criteria PMID 32034956; European guideline PMID 28639722); Burrows + papules in finger web-spaces / flexor wrists / axillae / periumbilical / genital (penile/scrotal nodules) / areolae — classic scabies distribution (2020 IACS criteria PMID 32034956); Itchy household / sexual / close contacts or an institutional cluster — the single strongest contextual pointer (European guideline PMID 28639722; WHO control PMID 31178154).

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Scabies — classic & crusted (Norwegian)** (derm.scabies.core.v1).
Phenotype framing: Terminal pruritic differential with named pivots: scabies vs atopic dermatitis (burrows + web-space + affected contacts + nocturnal itch + worsens-on-steroids pivot — route derm.atopic-dermatitis.core.v1) vs contact dermatitis (geometric/exposure-mapped pivot — route derm.contact-dermatitis.core.v1) vs dermatitis herpetiformis (grouped vesicles + extensor + IgA/gluten pivot) vs papular urticaria/insect bites (grouped urticarial papules, no burrows pivot) vs prurigo nodularis (chronic isolated nodules pivot) vs pediculosis (nits/lice pivot) vs asteatotic/xerotic eczema (dry crazy-paving, elderly winter pivot) vs cutaneous T-cell lymphoma (fixed poikilodermatous, crusted-mimic in immunocompromised — biopsy pivot) vs drug eruption (new-drug timeline pivot — route derm.drug-eruption.core.v1).
Scope: Frame as a Sarcoptes scabiei infestation with an IMMUNOLOGIC (delayed type-IV) itch that lags infestation by weeks — so itch timing, post-scabetic persistence, and "the whole household + the environment, not just the patient" define management. The great-imitator trap (missed as steroid-worsened eczema) and the classic-vs-crusted split (hyperinfestation, outbreak, sepsis) are set here.

No severity triggers fired against current inputs.

Plan

Regimen axis: **Scabies — stepwise scabicide ladder + contact & environmental control (2020 IACS / European 2017 / WHO NTD)** — step "Step 1 — First-line topical: permethrin 5% (whole-body, REPEAT day 7-14)".
1. permethrin 5% cream, whole body (neck-down; include scalp/face in infants/elderly/crusted) topical overnight 8-14 h then wash off; REPEAT on day 7-14 (topical_pyrethroid_scabicide, first line) — European guideline (PMID 28639722) + 2020 IACS (PMID 32034956) first-line topical; Cochrane 2018 (PMID 29608022) ~65-74% wk1-2 clearance, 1-3 applications ~93%; the mandatory day-7-14 repeat covers eggs surviving the first dose.
2. treat_all_close_household_sexual_contacts_simultaneously (public_health_intervention, first line) — European guideline (PMID 28639722) — ALL close/household/sexual contacts treated at the same time (even if asymptomatic), 2-month partner look-back; untreated contacts are the dominant re-infestation driver (2024 failure meta-analysis PMID 37625798).
3. environmental_decontamination_hotwash_seal_bag (public_health_intervention, first line) — European guideline (PMID 28639722) — hot-wash (≥50 °C) + hot tumble-dry, or seal in a plastic bag ≥72 h, all clothing/bedding/towels used in the prior 3-4 days; the off-host mite survives only ~24-36 h, days longer in crusted disease.

Setting playbook (outpatient) — Diagnose classic scabies by 2020 IACS criteria, treat the patient with first-line scabicide PLUS all contacts simultaneously PLUS environmental decontamination, and counsel post-scabetic itch so it is not misread as failure (2020 IACS PMID 32034956; European guideline PMID 28639722)
4. permethrin 5% (whole-body, repeat day 7-14) 5% cream topical overnight then repeat d7-14 — Classic scabies, any age ≥2 mo incl. pregnancy (European guideline PMID 28639722) (First-line topical; mandatory repeat covers surviving eggs (Cochrane 2018 PMID 29608022))
5. oral ivermectin 200 mcg/kg (day 1 + day 8) 200 mcg/kg PO d1 + d8 — Topical impractical/failed, extensive disease, outbreak (NOT pregnancy or <15 kg) (European guideline PMID 28639722) (2-dose ivermectin failure 7.1% vs single 15.2% (Mbuagbaw 2024 PMID 37625798))
6. precipitated sulfur 5-10% (neonates <2 mo, pregnancy) 5-10% in petrolatum topical daily x3 — Infant <2 mo or pregnancy when permethrin unsuitable (European guideline PMID 28639722) (Preferred safe option at the extremes of the age/pregnancy spectrum)
7. hydroxyzine + topical steroid (post-scabetic itch) 25 mg nocte PO PRN 2-4 wk — Residual itch after adequate treatment + treated contacts (2020 IACS PMID 32034956) (Post-scabetic hypersensitivity is expected — treat symptomatically, do NOT re-treat with scabicide)

Non-pharmacologic actions:
- Treat ALL close/household/sexual contacts simultaneously, even asymptomatic, with a 2-month look-back (European guideline PMID 28639722)
- Environmental decontamination: hot-wash + hot-dry or seal-bag ≥72 h all bedding/clothing/towels from the last 3-4 days (European guideline PMID 28639722)
- Written patient information + post-scabetic-itch counselling (itch persists 2-4 wk after cure — not failure) (2020 IACS PMID 32034956)
- STI screen + abstain from sexual contact until treatment complete if sexually acquired (European guideline PMID 28639722)

AVOID / contraindication checks:
- Oral ivermectin avoid in pregnancy and weight under 15kg (European guideline PMID 28639722 — use permethrin or precipitated sulfur instead)
- Precipitated sulfur preferred in neonates and infants under 2 months (European guideline PMID 28639722 — permethrin/ivermectin cautioned at this age)
- Permethrin or sulfur first line in pregnancy lactation (European guideline PMID 28639722)
- Do not manage as eczema with steroids alone (2020 IACS PMID 32034956 — the great imitator: topical/systemic steroids mask and worsen scabies)
- Crusted scabies requires barrier isolation and combined regimen (Hasan PLoS NTD 2020 PMID 33338053 — hyperinfestation is highly contagious and seeds outbreaks)
- Post scabetic itch is expected not failure do not reflexively re treat (2020 IACS PMID 32034956; 2024 failure meta analysis PMID 37625798)
- Always treat all contacts and the environment simultaneously (European guideline PMID 28639722 — single patient treatment guarantees re infestation)

Monitoring

Regimen monitoring:
- itch trajectory counselled post scabetic pruritus up to 2-4wk is normal (2020 IACS PMID 32034956)
- reassess at 2 and 4 weeks for eradication (European guideline PMID 28639722)
- treatment failure workup order: re-infestation > non-adherence/mis-application > post-scabetic-itch-misread > wrong-dx > true-resistance (2024 failure meta-analysis PMID 37625798 — 2-dose ivermectin if escalating)
- crusted scabies: serial skin scrapings until negative; eosinophilia/IgE + sepsis surveillance (Hasan PLoS NTD 2020 PMID 33338053)
- endemic/institutional: post-streptococcal-sequelae (urinalysis/BP for post-strep GN) after secondary impetigo + MDA-cohort follow-up (Thean Lancet Reg Health WP 2022 PMID 35345391; WHO framework PMID 34473725)

Setting (outpatient) monitoring:
- Recheck at 2 and 4 wk for eradication; expect declining (not zero) itch (European guideline PMID 28639722)
- If apparent failure: verify all contacts treated + adherence/application before re-treating (2024 failure meta-analysis PMID 37625798)

Follow-up plan: Confirm eradication at ~4 wk; ensure ALL contacts were treated (untreated contacts = the dominant recurrence driver); reinforce environmental decontamination; in endemic/institutional settings arrange surveillance, MDA linkage, and post-streptococcal-sequelae follow-up after secondary impetigo (urinalysis/BP for post-strep GN). Crusted scabies: relapse is common on return to an endemic community — plan repeat-screening and a low threshold to re-treat the index + cohort.
- Close-out criterion: eradication confirmed; contact + environment completion verified; endemic/crusted surveillance + post-strep-sequelae follow-up arranged

Monitoring phase: Set itch-trajectory expectations BEFORE discharge: post-scabetic pruritus may persist 2-4 wk after successful eradication and is NOT failure — manage with emollient/topical steroid/antihistamine, do not re-treat reflexively. Reassess at 2 and 4 wk. Apparent failure → structured workup: (1) re-infestation from an untreated contact (commonest), (2) non-adherence/mis-application, (3) post-scabetic itch misread, (4) wrong diagnosis, then (5) true persistence/resistance (rising over time per the 2024 meta-analysis) — escalate dose/agent only after 1-4 excluded.

Disposition

Current setting: outpatient — Diagnose classic scabies by 2020 IACS criteria, treat the patient with first-line scabicide PLUS all contacts simultaneously PLUS environmental decontamination, and counsel post-scabetic itch so it is not misread as failure (2020 IACS PMID 32034956; European guideline PMID 28639722)

Disposition criteria:
- Discharge with patient + all-contacts + environment plan and 2/4-wk recheck if classic and uncomplicated (European guideline PMID 28639722)
- Admit + isolate if crusted scabies, secondary sepsis, or unmanageable outbreak source (Hasan PMID 33338053)

Escalation triggers (move to higher acuity):
- Hyperkeratotic/crusted features or immunocompromise → crusted-scabies pathway + inpatient isolation (Hasan PLoS NTD 2020 PMID 33338053)
- Secondary bacterial sepsis / systemic toxicity → route OUT to the systemic-infection pathway (Hasan PMID 33338053)
- Institutional cluster → public-health notification + cohort/mass drug administration (WHO framework PMID 34473725)

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] Impetiginised / crusted scabies with systemic toxicity, bacteraemia, or rapidly worsening secondary infection
- [SEVERE] Hyperkeratotic, crusted, scaly plaques (± reduced/absent itch) in an immunocompromised / HIV / HTLV-1 / elderly / institutionalised / neurologic host — thousands–millions of mites, extremely contagious
- [SEVERE] Cluster of cases in an aged-care facility / shelter / prison / household network or a high-prevalence endemic community

Citations

- 2020 IACS Consensus Criteria for the Diagnosis of Scabies (Engelman et al, Br J Dermatol; PMID 32034956) + European guideline for the management of scabies (Salavastru et al, JEADV 2017; PMID 28639722) + WHO public-health control of scabies (Engelman et al, Lancet 2019; PMID 31178154) + WHO framework for scabies control (Engelman et al, PLoS NTD 2021; PMID 34473725) + Cochrane ivermectin/permethrin for scabies (Rosumeck et al, 2018; PMID 29608022) + Failure of scabies treatment systematic review/meta-analysis (Mbuagbaw et al, Br J Dermatol 2024; PMID 37625798) + Crusted scabies prospective cohort (Hasan et al, PLoS NTD 2020; PMID 33338053) + MDA for scabies control RCT (Romani et al, NEJM 2015; PMID 26650152) [PMID:32034956](https://pubmed.ncbi.nlm.nih.gov/32034956/)
- Cited evidence (PMID 28639722) [PMID:28639722](https://pubmed.ncbi.nlm.nih.gov/28639722/)
- Cited evidence (PMID 31178154) [PMID:31178154](https://pubmed.ncbi.nlm.nih.gov/31178154/)
- Cited evidence (PMID 34473725) [PMID:34473725](https://pubmed.ncbi.nlm.nih.gov/34473725/)
- Cited evidence (PMID 29608022) [PMID:29608022](https://pubmed.ncbi.nlm.nih.gov/29608022/)

Last reconciled with current guidelines: 2026-05-22.
References
  • 2020 IACS Consensus Criteria for the Diagnosis of Scabies (Engelman et al, Br J Dermatol; PMID 32034956) + European guideline for the management of scabies (Salavastru et al, JEADV 2017; PMID 28639722) + WHO public-health control of scabies (Engelman et al, Lancet 2019; PMID 31178154) + WHO framework for scabies control (Engelman et al, PLoS NTD 2021; PMID 34473725) + Cochrane ivermectin/permethrin for scabies (Rosumeck et al, 2018; PMID 29608022) + Failure of scabies treatment systematic review/meta-analysis (Mbuagbaw et al, Br J Dermatol 2024; PMID 37625798) + Crusted scabies prospective cohort (Hasan et al, PLoS NTD 2020; PMID 33338053) + MDA for scabies control RCT (Romani et al, NEJM 2015; PMID 26650152) — PMID:32034956
  • Cited evidence (PMID 28639722) — PMID:28639722
  • Cited evidence (PMID 31178154) — PMID:31178154
  • Cited evidence (PMID 34473725) — PMID:34473725
  • Cited evidence (PMID 29608022) — PMID:29608022