What is Scabies?
July 3, 2009
Scabies is a common contagious disease that results when the human itch mite (Sarcoptes scabiei) burrows into the skin and lays eggs. The infection spreads from skin to skin (even sexual) and is associated with crowded and dirty living conditions. Nosocomial infection is also common. After infestation, symptoms appear 4-5 weeks after infection.
Symptoms
The symptoms result due to hypersensitivity reaction against the mite faeces. The pruritis increases during night and after a hot shower. There is intense itching that leads to excoriations. Scaling and erythema also appear. Atypical manifestations are seen in immuno-suppressed patients.
On examination, excoriations, papules and vesicles are seen. Sometimes, mite burrows are seen on the wrists, between the fingers, elbows, feet, ankles, waistline, buttocks, axillae, groin and genitals. In case of secondary infection, pustules may also arise.
Scabies may also be present in clean patients in whom frequent washing / bathing washes the mites away and their burrows cannot be found easily.
Scabies is often over-looked in elderly where severe itching gets masked due to dry skin and sometimes due to bed-ridden conditions. In such people, external manifestations are more due to lowered immunity.
In infants, the symptoms are often widespread, even involving the palms and soles as well.
Diagnosis
Skin biopsy of nodules reveals portions of mite in the corneal layer (though performed rarely). Examination with magnifying lens shows typical burrows at the site. The mite can be extracted with a needle and examined microscopically. Other tests include potassium hydroxide test and burrow ink test.
Treatment
Treatment regime aims at treating the patient as well as the close contacts and family members. Bedding, towel and clothing are to be washed in hot water so as to prevent re-infestation.
Normal routine activity is to be followed along with normal diet. No dietary restrictions or special diet are to be observed.
First line treatment comprises of local applications and anti-histamines. Patients are to be cautioned for not over-using the medication when applying to the skin. Re-checking with the physician at weekly intervals is often required.
Prognosis
With treatment, the lesions begin to regress in 1-2 days even with worst itching. Sometimes, the symptoms may remain for about 10-12 days.
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