Definitions of the levels of evidence (I-IV) and grades of recommendation (A-C) are defined at the end of the "Major Recommendations" field.
Diagnosis
- The clinical appearance is usually typical, but there may be diagnostic confusion with other itching conditions such as eczema.
- Scrapings taken from burrows may be examined under light microscopy to reveal mites.
Management
General Advice
- Patients should be advised to avoid close body contact until they and their partner(s) have completed treatment.
- Patients should be given a detailed explanation of their condition, and clear and accurate written information on applying the treatment.
Further Investigation
- A full screen for other sexually transmitted infections (STIs) should be undertaken, as there is anecdotal evidence of rates of infection similar to other patients attending Genitourinary Medicine (GUM) clinics.
Treatment
Two topical treatments are recommended in the United Kingdom (UK). Benzyl benzoate is regarded as too irritant, and crotamiton is ineffective compared to the recommended options.
Recommended Regimens
- Permethrin 5% cream (Level of evidence Ib, Grade of recommendation A)
- Malathion 0.5% aqueous lotion (Level of evidence IV, Grade of recommendation C)
These should be applied to the whole body from the neck downwards, and washed off after 12 hours, usually overnight.
Itch may persist for several weeks. Application of crotamiton cream may give symptomatic relief and antihistamines may also be helpful.
Potentially contaminated clothes and bedding should be washed at high temperature (>50 degrees C) if possible.
Mites separated from the human host die within 72 hours.
Norwegian scabies may be treated with oral Ivermectin, available on a named-patient basis, in a dose of 200 mcg/kg. Deaths in elderly patients treated with this drug have not been seen in other settings.
Allergy
Treatments to which there is known hypersensitivity should be avoided.
Pregnancy and Breastfeeding
Permethrin is safe during pregnancy or breast-feeding.
Sexual Partners
- Current sexual partners as well as other members of the household should be examined and treated.
- An arbitrary time span widely quoted is for contacts from the previous 2 months to be traced.
Follow-Up
- No clear evidence exists as to optimal follow-up
- The appearance of new burrows at any stage post-treatment is indicative of a need for further therapy, although in re-infection symptoms of pruritus may recur before typical burrows have developed.
- Pruritus persisting more than 2 weeks after treatment may reflect treatment failure, reinfection or drug allergy to anti-scabetics.
Definitions:
Levels of Evidence
Ia: Evidence obtained from meta-analysis of randomised controlled trials
Ib: Evidence obtained from at least one randomised controlled trial
IIa: Evidence obtained from at least one well designed controlled study without randomisation
IIb: Evidence obtained from at least one other type of well designed quasi-experimental study
III: Evidence obtained from well designed non-experimental descriptive studies such as comparative studies, correlation studies, and case control studies
IV: Evidence obtained from expert committee reports or opinions and/or clinical experience of respected authorities
Grading of Recommendations
A (Evidence levels Ia, Ib)
- Requires at least one randomised controlled trial as part of the body of literature of overall good quality and consistency addressing the specific recommendation.
B (Evidence levels IIa, IIb, III)
- Requires availability of well conducted clinical studies but no randomised clinical trials on the topic of recommendation.
C (Evidence level IV)
- Requires evidence from expert committee reports or opinions and/or clinical experience of respected authorities. Indicates absence of directly applicable studies of good quality.
