Scabies is a common skin condition caused by the Sarcoptes Scabiei mite. .
The tiny mites lay eggs in the skin, leaving silvery grey lines that are commonly seen between the fingers, on the palms and around the wrists. As the rash spreads it can have a varied appearance, often with erythematous papules, sometimes with small vesicles. Infants may have pustules on the palms and soles. The trunk and limbs are often affected, with the face and scalp spared.
It presents with itching as the main symptom and this is often worse at night.
Scabies is passed by skin-to-skin contact and is highly infectious.
Treatment is with an insecticide such as malathion 0.5%. The whole household must be treated and all bedding and clothing washed at 60 degrees. Treatment should be repeated after 7-10 days ensure that newly hatched mites are treated. Children should be excluded from school/childcare until the first treatment has been carried out.
Secondary skin infection, usually with staphylococcus, can be a complication and should be treated with antibiotics.
Crusted scabies is a highly contagious hyperinfestation with sarcoptes scabei var hominis. It is a presentation of scabies in an immunocompromised patient. It can also be found in patients who live in long-term care facilities or institutions. It initially appears as poorly defined red patches which then develop into thick scaly plaques, most often found between the fingers or over the palms and soles. Itching can be minimal or absent. If diagnosed a dermatology or infectious disease team should be involved in the care of the patient and their contacts, depending on local protocol. Treatment usually comprises of oral ivermectin which is dosed according to the severity of the disease. Topical insecticides and scabicide (such as 5% permethrin) may also be added
References
https://dermnetnz.org/topics/scabies/
https://dermnetnz.org/topics/crusted-scabies/
https://www.nhsinform.scot/illnesses-and-conditions/skin-hair-and-nails/scabies