Scabies

K Pavithran

 Department of Dermato-Venereology, Malabar Institute of Medical Sciences, Calicut-673 016, India

Correspondence Address:
K Pavithran
Department of Dermato-Venereology, Malabar Institute of Medical Sciences, Calicut-673 016
India

Scabies caused by Sarcoptes scabies var hominis continues to be a common dermatologic problem in clinical practice. With advent of AIDS and with more number of patients on immunosuppressant drugs after organ transplantation, the number of cases of scabies keratotica is on the increase.

Secondary bacterial infection and eczematisation are the common complications of scabies.

If secondary infection is severe I treat if with antibiotic preferably penicillin or erythromycin, before anti scabetic preparation is applied. When there is eczematisation a short course of systemic steroid is given along with antibiotic. When the patient has puffiness of face, oedema of legs or history of oliguria or haematuria, urinalysis and estimation of blood urea and serum creatinine are advised, to exclude acute alomerulonephritis.

The topical antiscabetic preparations I prefer for adults are: permethrin 5% gammaxene 5% or benzyl benzoate 25% emulsion. For infants permefhrin or 2.5% sulphur in soft paraffin are used.

After a scrub bath, the medicine is applied all over the skin surface below neck (for infants and immuno compromised, application is from scalp to toes). Permethrin is applied for 8-12 hours, gammaxene for 12 hours and if it is benzyle benzoate 12 hourly by 3 applications is advised and patient has to fake bath 24 hours after the last bath. For children, to minimize irritation benzyl benzoate emulsion is to be diluted with equal quantity of water or lotio calamine.

The medicine should be applied under the free edge of nails and gluteal fold also.

For patients with scabies keratotica application of medicine should be from scalp to toe and repeated weekly for 2-3 weeks. Over the thick keratotic areas, the antiscabetic should be applied daily till no live mites are seen in scales.

In case of nodular scabies after application of the antiscabetic, topical potent steroid (clobetasol propionate) or intralesional triamcinolone acetonide 0.1 to 0.2 ml (10mg/ ml) in each nodule is advised.

Itching may persist even after application of antiscabetic preparations. For this, application of calamine cream and oral antihistamine will be enough in most cases. If itching persists even after 2 weeks, a second application of the antiscabetic medicine is recommended.

• All family members or exposed persons are to be treated simultaneously for scabies.
• All confad objects such as table, chair, bed sheet and clothes should be disinfected.

More recently I am using oral ivermectin in some cases of scabies. For adults weighing 50 to 65kg it is given as a single dose of 2 tablets of 6mg each and for children 25 to 35 kg one tablet of 6mg strength. I do not give it for children below 5 years and for pregnant women.