Scabies

Clinical history

• A history of pruritus that worsens at night and concurrent history of itching among family members and/or sexual or household contacts is suggestive of scabies.

Symptoms

• The main symptom, which may take 3-6 weeks to develop (1-3 days in cases of re-infection), is intense itch – usually worse at night
• The itch is caused by the direct effects of the host-mite interactions, as well as a delayed type-IV hypersensitivity reaction to the mite and its faeces and eggs

Signs

• Erythematous papules, typically seen in the interdigital web spaces, sides of fingers, flexor aspects of wrists, extensor aspects of elbows, anterior and posterior axillary folds, around nipples, penis and scrotum, around the umbilicus, medial aspect of thighs, buttocks, sides and back of feet.
• Characteristic silvery lines may be seen in the skin where mites have burrowed – these are pathognomonic of scabies
• Nodules may be seen especially on the penis, scrotum, the areola, the buttocks, groin and axillary regions
• These nodules are intensely itchy and may persist after treatment
• In HIV infection crusted lesions that teem with mites (Crusted Scabies) pose a significant risk of scabies infection transmission. See BASHH guideline for more information
• Scabies incognito this refers to the altered clinical pictures seen following use of topical steroids and consists of widespread atypical papular lesions that may mimic other generalised forms of eczema, symptoms are masked but patient remains infectious

• Scabies is a clinical diagnosis that should be suspected on the basis of symptoms, signs and risk factors as described above. Diagnosis is usually made clinically from the appearance of excoriated papules, burrows and nodules at sites of predilection.
• Itchy papules and nodules on the penis are almost certainly scabetic
• Examine scrapings from burrows under light microscopy or use a magnifying glass to examine lesions

• Advise patient on how scabies is transmitted including by fomite transmission
  Patients should be given a detailed explanation of their condition, and clear and accurate written information on applying the treatment.
  • https://www.skinhealthinfo.org.uk/condition/scabies/
  • https://www.pcds.org.uk/patient-info-leaflets/scabies 
• All clothes, soft slippers, towels and bed linen of the affected case should be machine-washed for at least 35 minutes at a minimum of 50 degrees C and /or tumble dried on a high heat setting (50-120 degrees C) for 10-35 minutes on the day of application of the first treatment.
• If clothes cannot be laundered at high temperature, they can be sealed in plastic bags for 4 days at room temperature, after which mites are unlikely to survive.
• Inform patients about proper application of topical scabicides (esp ankles, under finger nails, between toes, sacral region)
• Offer STI screening including HIV.
• Avoid body contact until they and their partner(s) have completed treatment and follow up
• May be able to help itch with antihistamines + crotamiton (Eurax®) cream
• Symptoms may take more than 4 weeks to resolve– retreatment too soon often results in the development of hypersensitivity to scabicide, thus compounding the itch.

First line treatment** for classical scabies

** Both treatments have similar effectiveness in clinical trials and decision should be based on individual clinical circumstances

Table 1

Alternative Treatments

• There are several alternative treatments available. Please refer to BASHH guideline.

Treatment of Crusted Scabies

• Treatment should be discussed with a senior colleague familiar with the condition

Complications

• Secondary Infection of the skin lesions can occur following repeated scratching
  Partner notification.
• Trace and treat all sexual and household or institutional contacts over previous 2 months prior to onset of symptoms.

Follow up

• Re-treat if new burrows appear.
• Itching following initial treatment is common. Anti-Histamines and optimising skin care can help.
• If the Scabies mites have been eradicated and eczematous areas are present then a potent topical corticosteroid ointment may be helpful.
• Pruritus persisting more than 4 weeks after second dose of treatment may reflect treatment failure, reinfection or drug allergy to anti-scabetics. Re-examine and d/w senior clinician.

1. BASHH Guidelines [Internet]. SAGE Publications Ltd. 2016 UK National Guideline on the Management of Scabies. Available from: https://bashhguidelines.org/media/1137/scabies-2016.pdf [accessed online June2025]