Please enable JavaScript.
Coggle requires JavaScript to display documents.
Scabies burrows (Risk factors (Crowded living conditions,…
Scabies burrows
Risk factors
Crowded living conditions
Institutionalisation
Contact with infested person
Immunocompromised (crusted scabies)
Female
Clinical
presentation
Itching
(worse at night)
Linear burrows
Wavy, thready, white/grey lines,
small vesicle with black dot at end;
fingers and wrists
Erythematous papules/vesicles/pustules
Interdigital spaces, sides of fingers,
wrists, elbows, axilla, genital area
Violet nodules
Groin, buttocks, axilla
Pruritic
Complications
Secondary bacterial infection
S aureus, GAS - impetigo, folliculitis, furunculosis, abscess
Secondary eczematisation
Due to scratching and irritant meds
Nodular scabies
Pruritic nodules in axilla and groin
(prolonged immune response to mite antigens)
Sepsis
Risk in crusted scabies
Epidemiology
F>M
Teens (10-19y)
Low SEC
Diagnosis
Examination
Dermatological
Linear burrows, erythematous papules, nodules,
crusted scabies
Investigation
Bedside
Ink burrow test: blue/black ink to papule, removed with alcohol;
+ve test = dark zigzag line running away from lesion (mite burrow)
Biopsy
Skin scrapings for microscopy (parasites, eggs, faeces)
High specificity but low sensitivity
History
DH
Current meds (immunosuppressants),
allergies
FH
Others affected
SH
Living conditions, smoking, alcohol
Sexual contact/history
PMH
Other medical conditions, immunocompromised
PC/HPC
Site, onset, character (itchy, red, scaly, nodules, papules),
systemic symptoms, red flags, others affected
Pathophysiology
Infection
Parasite (scarcoptes scabeii) burrows into epidermis through the stratum corneum, lays eggs and dies
Immune response to the mites and saliva/eggs/faeces causes the itching
Spread by skin-skin contact, often sexually
Incubation period 3-6wk; mites can survive away from host for up to 7 days
Hyperinfection
Crusted scabies, caused by hundreds/millions of mites
in exfoliating scales
Immunocompromised host
Management
Medical
Topical insecticide
Indication: uncomplicated scables
E.g. permethrin 5% cream, malathion 0.5% cream
MOA: apply to whole body from chin downwards, special attention to affected areas, kills parasite, wash off after 8-12h
Second application 1 week later
Anti-pruritic
Indication: post-scabies itch
E.g. crotamiton 10% cream
MOA: antiparasitic and antipruritic
Antihistamine
Indication: nighttime itching
E.g. chlorphenamine PO nocte
MOA: reduces itch by inhibiting histamine release,
also sedative to aid sleep
Steroids
Indication: nodular scabies
E.g. topical or PO
MOA: reduces inflammation, reducing nodules
Oral insecticide
Indication: severe scabies
E.g. PO ivermectin
Conservative
Information and advice
Partner/family notification and treatment
Hygeine advice (thorough scrubbing and drying after washing, avoid close contact, sharing towels etc.)
Hot wash of bedding, clothing towels
Referral to specialist/admission if crusted scabies,
young children <2m old, or nodular scabies
Prognosis
Often resolves quickly with treatment
Itching may continue for 2wk after treatment
Diagnosis
Itchy skin disorder caused by
infestation with scabies parasite
