Scabies

DR.M ABBAS SUBHANI
MBBS DCH

------------------------------------------------------------------------------------------------------------------------

Presentation

The usual complaint is generalized itching, especially at night.The characteristic lesion is the burrow, a short serpiginous ridge that ends with a vesicle(pearl shaped).
The most common sites are the interdigital webs,the flexor aspects of the wrists, the nipples,the axillae,the extensor surface of the elbows,and the abdomen and genitalia. However,the head, neck, palms, and soles are frequently involved in infants and young children. In small children the leisions may be widespread and secondarily infected. A papular or  pustular itchy skin lesion at the buttocks, upper back or abdomen is highly suggestive of scabies ( even if the burrows are not found).Erythematous,excoriated papules and vesicles are common findings with secondary crusts, eczematization, and bacterial infection.The lesions will vary,based on the duration of infection and degree of sensitization of the individual.

Diagnosis

Scabies is a "great imitator" of other itchy eruptions; however, a history of contact. intense pruritus, and the variable lesions suggest the diagnosis.
Atopic dermatitis most commonly occurs on the flexor surfaces and not in the interdigital webs.
The lesions of pityriasis rosea are well circumscribed and not on the distal extremities.
Folliculitis can be identified by the hair shaft in each lesion. Since the lesions of scabies can become impetiginized, differentiation may be very difficult although pruritus is not intense in impetigo.
To confirm the diagnosis of scabies, microscopy is needed but it is not practicable for majority of the primary care physicians. There is no harm in using the the drugs to treat scabies on suspicion.

Treatment

If there is secondary infection, it is to be treated. Treatment is done with the local application of drugs. Age of the child is important for the selction of the treatment. Following drugs may be used

• gamma benzene hexachloride 1 % --after bath apply this on entire body 8-12 hourly. It is not to be used below 2 years of age as chance of neurotoxocity is more. It is also to be avoided for the pregnant ladies.
• crotamiton 10 % --there are no systemic side effects, it is to be applied once in 24 hour, repeat it on next day.
• Benzyl benzoate solution-- apply it on whole body for 3 consecutive night.
• Sulphar in petroleum--- has also been used
• Maintenance of personal hygiene is very important-- in addition to the use of drugs, personal hygiene is very important in the control of infection. Clothes and bed linen of all the house hold members should be boiled for quite long time.

Key considerations

• High index of suspicion is needed, otherwise one may miss the diagnosis as it is a "great imitator" of other itchy eruptions.There is no harm in therapeutic trial on suspicion
• It spreads like wild fire, it is unlikely that contancts are free from infection, they also need simultaneous treatment.
• Some of the drugs used for adults are not safe for the children
• The itching may persist for few days even after effective treatment.

Pictures of scabies

Please click on the link to see the images of scabies. Pictures are very helpful for the identification of scabies.