Doctors Revision

Dermatology (Skin Conditions)

Scabies

A contagious skin infestation caused by the mite Sarcoptes scabiei var. hominis, characterized by intense itching, papules, and burrows.

Open in the interactive guide
On this page

Referral and warning signs

When to refer

Refer if: Diagnosis uncertain. Crusted (Norwegian) scabies suspected. Failure of standard topical treatment. Widespread secondary infection requiring systemic antibiotics/admission.

Red flags

  • Extensive crusting (Norwegian scabies).
  • Widespread severe secondary bacterial infection / cellulitis / sepsis.

Signs and symptoms

  • Intense Itching (Pruritus): Especially severe at night.
  • Skin Lesions:
  • - Small erythematous papules, vesicles, or wheals.
  • - Burrows: Thin, greyish/brownish, thread-like lines (often short, S-shaped) on the skin surface, where the female mite tunnels. Often difficult to see.
  • - Excoriations (scratch marks).
  • - Secondary bacterial infection (impetiginization) common due to scratching.
  • Typical Distribution: Finger webs, wrists (flexor aspect), elbows, axillae, belt line, buttocks, nipples (females), genitalia (males). Scalp and face usually spared in adults, but can be involved in infants and immunocompromised.
  • Crusted (Norwegian) Scabies: Severe form in immunocompromised or debilitated individuals, characterized by thick crusts teeming with mites, less itching may occur.

Risk factors

  • Close physical contact with an infected person (household, sexual).
  • Crowded living conditions (institutions, camps).
  • Poor hygiene.
  • Immunosuppression (risk of crusted scabies).

Diagnosis

Clinical assessment

Diagnosis usually based on characteristic intense nocturnal itching AND typical distribution of lesions (papules, burrows) AND history of contact with affected individuals.

Differential diagnosis

  • Eczema (Atopic, Contact).
  • Insect bites (Papular urticaria).
  • Drug reactions.
  • Dermatitis herpetiformis.
  • Lichen planus.
  • Folliculitis.

Investigations

  • Usually clinical diagnosis.
  • Microscopy: Skin scraping from a burrow (use blade with mineral oil), examine under microscope for mites, eggs, or faecal pellets (scybala). Confirmatory but often negative.
  • Dermoscopy: Can sometimes visualize mite/burrow.

Diagnostic criteria

Clinical diagnosis based on itching, typical lesions/distribution, and contact history. Microscopy confirms if positive.

Management

Non-pharmacological management

  • Treat Patient AND All Household Members/Close Contacts SIMULTANEOUSLY, even if asymptomatic.
  • Wash all bedding, clothing, towels used in last 3 days in HOT water (>50°C) and dry in hot dryer or seal in plastic bag for 72 hours.
  • Vacuum carpets/upholstery.

Pharmacological treatment

  • Topical Scabicide (First-line):
  • - Permethrin 5% Cream: Apply thoroughly from neck down to soles of feet (include scalp/face in infants/elderly). Leave on for 8-14 hours (overnight), then wash off. Repeat application in 7 days. (Often preferred due to efficacy/safety).
  • - Benzyl Benzoate 25% Lotion: Apply neck-down as above for 2 consecutive nights (wash off in morning). May need repeating after 7 days. Can be irritating. Dilute for children (1 part lotion to 1 part water <12y; 1 part lotion to 3 parts water <2y). (UCG recommended option - LOC: HC2).
  • Oral Scabicide:
  • - Ivermectin: 200 mcg/kg PO single dose, repeat in 7-14 days. Useful for outbreaks, crusted scabies, or if topical treatment difficult/failed. Avoid in pregnancy, breastfeeding, children <15kg or <2 years old (UCG). (LOC: HC3)
  • Symptomatic Relief:
  • - Antihistamines: (e.g., Chlorphenamine 4mg TID, Cetirizine 10mg OD) for itching, which may persist for weeks after successful treatment. (LOC: HC2)
  • - Topical Corticosteroids: (Mild-moderate potency) for persistent itchy papules/eczema after scabies treated.
  • Secondary Bacterial Infection:
  • - Topical antiseptics/antibiotics (Mupirocin) or Systemic antibiotics (Cloxacillin/Erythromycin) if significant impetiginization/cellulitis present. (LOC: HC2)

Monitoring

Assess for resolution of itching and new lesions. Itching may persist for 2-4 weeks after successful treatment due to hypersensitivity.

Complications

  • Secondary bacterial infection (impetigo, cellulitis, abscess).
  • Post-scabetic eczema/nodules (persistent itching/lumps).
  • Crusted (Norwegian) scabies.
  • Social stigma.
  • Sleep disturbance.

Prevention

  • Avoid close physical contact with infected individuals until treated.
  • Treat all contacts simultaneously.
  • Environmental decontamination (washing linen/clothing).
  • Maintain good personal hygiene.

Patient education

  • Explanation of scabies as a mite infestation, highly contagious.
  • CRITICAL importance of treating ALL household members/close contacts at the SAME TIME.
  • Correct application technique for topical scabicide (neck down, leave on time, repeat).
  • Environmental measures (washing bedding/clothing).
  • Reassurance that itching may persist for weeks after treatment and how to manage (antihistamines).
  • When to seek review if new lesions appear or infection suspected.

Uganda-specific notes

Scabies is common, particularly in crowded settings. Benzyl Benzoate is widely available and recommended by UCG. Permethrin and Ivermectin access may be more limited. Emphasize treating all contacts and environmental cleaning.

References

  • Uganda Clinical Guidelines (UCG) 2023

    Chapter 22, Section 22.4.1

Scroll to Top