Scabies and lice: AU general practice diagnosis and treatment

Scabies and lice are ectoparasite infestations that present frequently in general practice across every demographic in Australia — from childcare-age children with head lice, to adolescents with pubic lice, to residents in aged care facilities with crusted scabies, to remote ATSI communities where classic scabies affects up to half of all children at any given time. Both conditions are curable; the barriers to clearance are almost always logistical (incomplete contact treatment, missed re-application, reinfestation from untreated environment) rather than pharmacological. This article covers the GP-level approach to diagnosis, treatment, and outbreak management according to eTG Dermatology 2024 and NHMRC Healthy Skin Program guidance.

A — Clinical assessment: recognising the infestation

Scabies presentation and examination

The hallmark of scabies is intense nocturnal itch — worse at night because mites are more active when the body warms under bedding. On first exposure, itching is delayed 4–6 weeks as sensitisation develops; reinfested individuals itch within 24–48 hours. The itch is typically generalised and out of proportion to visible skin changes, and often worse after a hot shower.

Pathognomonic lesion: the burrow — a 5–15 mm sinuous, thread-like, slightly raised track, grey-white or skin-coloured, found in the web spaces of fingers, wrists, medial borders of the hands, axillae, umbilicus, buttocks, genitals (especially the glans and shaft of the penis), and around the areolae. In infants, burrows can appear on the palms, soles, and face/scalp (areas spared in adults with intact immunity). Burrows are often obscured by secondary eczematisation and excoriation.

Dermoscopy: the delta-wing-jet sign — a triangular dark body (the mite) with a leading V-shaped track — is specific for scabies and assists confident diagnosis in atypical presentations (Australasian College of Dermatologists).

Differential diagnosis includes atopic dermatitis, contact dermatitis, and prurigo nodularis. The key distinguishing features are: nocturnal predominance, genital or finger-web involvement, and the pattern of household clustering (multiple household members itching simultaneously points strongly to scabies).

Crusted (Norwegian) scabies presents as thick hyperkeratotic plaques, particularly on hands, feet, elbows, and the scalp, often with minimal itch despite massive mite burden. It may be misdiagnosed as severe psoriasis or seborrhoeic dermatitis. Any residential or hospital outbreak with spreading crusted skin disease should trigger urgent dermatology or infectious diseases involvement.

Lice: three clinical entities

Head lice (Pediculus humanus capitis): concentrated on the scalp, especially behind the ears and at the nape. Live lice are fast-moving and difficult to spot; diagnosis is confirmed by finding live lice, not nits (egg casings) alone — empty white nits more than 10 mm from the scalp indicate past, not active, infestation. Detection combing with a fine-toothed comb (louse comb) on conditioner-coated wet hair is the most sensitive diagnostic method.

Body lice (Pediculus humanus corporis): found in clothing seams, not on skin; associated with homelessness and displacement. Body lice are significant because they are vectors for typhus (Rickettsia prowazekii), trench fever (Bartonella quintana), and relapsing fever (Borrelia recurrentis) — rare in Australia but important in returning travellers and asylum seekers. Treatment is environmental (hot-launder all clothing and bedding); topical therapy is not required.

Pubic lice (Phthirus pubis, ‘crabs’): found in coarse hair — pubic, perianal, axillary, eyelashes, eyebrows. Diagnosis is clinical; STI co-testing is indicated in all adults. In children, pubic lice are a sentinel finding for sexual abuse and require a child protection assessment.

B — Evidence for treatment

Permethrin 5% for scabies

Permethrin 5% cream remains first-line for classic scabies in non-pregnant adults and children over 2 months. It is a synthetic pyrethroid that disrupts sodium channels in mite nerve membranes. Clinical cure rates exceed 90% with correct application technique. The most common reason for treatment failure is inadequate application — missing skin folds, under-fingernails, or genitals — and failure to treat contacts simultaneously.

Application protocol (eTG-compliant):

• Apply to all skin from the neck down, including between the fingers and toes, under fingernail tips, the buttock cleft, and genitals
• In infants under 2 years and immunocompromised adults, include the face and scalp (avoiding eyes and mouth)
• Leave in place for 8–12 hours (overnight application is practical)
• Wash off thoroughly and launder worn clothing and bedding
• Repeat on day 7

Itch may persist for 2–4 weeks after successful treatment due to residual mite antigens — this does not indicate treatment failure. A topical corticosteroid (moderate-potency, brief course) can provide symptomatic relief.

Ivermectin for scabies

Oral ivermectin 200 mcg/kg has equivalent efficacy to permethrin for classic scabies and is superior in crusted scabies and mass treatment settings. The landmark MASS trial (Romani et al., NEJM 2019) demonstrated that ivermectin-based mass drug administration in a Fiji community achieved higher prevalence reduction than permethrin-based mass treatment.

In Australian general practice, PBS ivermectin is Authority Required for:

• Crusted scabies
• Scabies in institutional or community outbreak
• Failure of two courses of topical therapy
• Management in vulnerable communities (including remote ATSI settings)

Ivermectin is taken on an empty stomach, repeated at day 7. For crusted scabies, doses may extend to days 0, 1, 7, 8, 14, and 15 in combination with topical permethrin and a keratolytic. Weight-based dosing: 200 mcg/kg (round up to nearest 3 mg tablet).

Contraindications: pregnancy, breastfeeding (infant under 15 kg), children under 5 years or weighing under 15 kg. See TGA prescribing information.

Lice treatment evidence

For head lice, randomised trials and systematic reviews support:

• Dimethicone 4% (Hedrin, generic silicone lotion): physical agent, not affected by insecticide resistance; leave 8 hours or overnight, repeat day 7
• Wet combing (Bug Busting technique): effective when done thoroughly every 3–4 days for 2 weeks; suitable in pregnancy and infancy
• Malathion 0.5% (Derbac-M): organophosphate; effective but strong odour; not recommended in asthmatics or in children under 6 months
• Permethrin 1% rinse: lower cure rates than dimethicone in recent Australian studies, reflecting emerging resistance

No regimen removes all surviving nits; all require retreatment at day 7 to intercept newly hatched lice before they reach reproductive age.

C — Scabies-specific management: contacts, environment, and outbreak control

Simultaneous contact treatment

All household contacts and sexual partners must be treated on the same night as the index case, regardless of whether they have symptoms. The latency period of initial infestation (4–6 weeks of asymptomatic carriage) means untreated contacts are almost certainly infested. Advise every family to pre-position all permethrin tubes, arrange the same treatment night, and confirm completion.

Environmental decontamination

Sarcoptes scabiei mites survive off the host for up to 72 hours at room temperature. The following measures interrupt environmental reinfestation:

• Hot-wash (≥60 °C) all clothing, bedding, and towels used in the 72 hours before treatment
• Items that cannot be washed (soft toys, cushion covers) should be sealed in a plastic bag for at least 7 days
• No special cleaning of surfaces (floors, furniture) is required — mites do not survive long on surfaces and environmental sprays are ineffective

Institutional outbreaks

One case of crusted scabies in a residential aged care facility, hospital ward, or disability residential service should be treated as an outbreak. All residents and staff exposed to the index case require simultaneous treatment and environmental decontamination. Contact the relevant state or territory public health unit for outbreak management guidance. The CDNA national guidelines provide detailed protocols for aged care and institutional settings.

D — Australian operational context: MBS and PBS items, Healthy Skin programs

Relevant MBS items

Item	Description
23 / 36 / 44	Standard GP consultation (scabies diagnosis and management plan)
715	ATSI Health Assessment — identifies skin disease including scabies as a priority
81300–81360	Aboriginal and Torres Strait Islander specific items under PHN-negotiated arrangements

PBS items relevant to scabies and lice

Drug	PBS listing	Notes
Permethrin 5% cream	General benefit (no Authority)	First-line; available at PBS co-payment
Ivermectin 3 mg tablets	Authority Required	For crusted scabies, outbreaks, two-topical failures
Benzyl benzoate 25% lotion	Non-PBS (private script or RPBS)	Alternative when permethrin unavailable

ATSI Healthy Skin programs

Remote Aboriginal and Torres Strait Islander communities bear a disproportionate burden of scabies, with point prevalence in children reported at 30–50% in some communities and up to 71% in some survey cohorts. Secondary impetigo (Staphylococcus aureus / Streptococcus pyogenes) following scabies excoriation drives the epidemiology of post-streptococcal glomerulonephritis and acute rheumatic fever in these communities.

The NHMRC Healthy Skin Program and the Australian Healthy Skin Consortium provide community-level mass treatment protocols and resources tailored to remote settings. GPs working in or referring to ACCHO (Aboriginal Community Controlled Health Organisation) services should engage local skin health coordinators when community-level outbreaks are identified.

Ivermectin mass drug administration (MDA) in conjunction with topical permethrin has been trialled successfully in several Australian remote community settings under Queensland Health and NT Health protocols, achieving sustained prevalence reduction when combined with housing improvement and hygiene infrastructure.

E — Special populations

Pregnancy and breastfeeding

Permethrin 5% cream is the treatment of choice in pregnancy (Category B1 in Australian classification). Systemic absorption is minimal. Ivermectin is avoided due to insufficient reproductive safety data. In breastfeeding, if treatment with permethrin is not feasible, temporarily express and discard milk for the duration of overnight application; resume breastfeeding after the cream has been washed off.

Immunocompromised patients

Patients with HIV, haematological malignancy, transplant immunosuppression, or high-dose corticosteroid use are at risk of crusted scabies. Classic scabies in immunocompromised patients may present atypically — with psoriasiform plaques rather than burrows — and should prompt early dermatology review. Treatment should be combination oral ivermectin plus topical permethrin from the outset; standard topical monotherapy frequently fails.

Aged care and disability residential settings

Scabies in residential settings can pass undetected for months when misattributed to dry skin or existing dermatological conditions in residents with cognitive impairment. Any cluster of unexplained itch across multiple residents should prompt scabies screening. Early outbreak recognition and simultaneous treatment of all residents and staff, coordinated with infection prevention and control teams, is essential to avoid facility-wide spread.

Children and schools

Head lice are most prevalent in primary school–age children (5–11 years). Reassure families that head lice do not indicate poor hygiene — they prefer clean hair, transmit only by head-to-head contact (not sharing combs or hats), and are not a serious health risk. Post-treatment school return the following day is permitted under all Australian state and territory guidelines; school exclusion policies requiring nit-free certificates are outdated and not supported by evidence.

In infants under 2 months, permethrin is contraindicated; specialist paediatric dermatology advice should be sought.

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When to escalate

Refer to or discuss with a dermatologist or infectious diseases physician when:

• Crusted scabies is suspected (especially in residential facilities)
• Classic scabies fails to respond after two correctly applied courses of topical therapy plus simultaneous contact treatment
• An institutional outbreak involves more than one confirmed case and contact tracing is complex
• Pubic lice in a child requires a mandatory child protection referral

What this article is and is not

This article is written for clinicians practising in Australian general practice and is based on eTG Dermatology 2024 and NHMRC guidance. It summarises current practice guidance and is not a substitute for clinical judgement applied to individual patients. Drug dosing and PBS Authority criteria should always be confirmed against current prescribing information and the PBS schedule at the time of prescribing.

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Sources cited