How does a sarcoptic mite present and how is it treated? - briefly
The infestation causes intense pruritus and characteristic linear or serpentine burrows with erythematous papules, most often on wrists, elbows, and intertriginous zones. Effective therapy consists of a single application of 5 % permethrin cream or a dose of oral ivermectin, frequently combined for rapid eradication.
How does a sarcoptic mite present and how is it treated? - in detail
Sarcoptes scabiei is an obligate ectoparasite that burrows into the epidermis of humans, causing a highly pruritic dermatosis. The infestation typically manifests within two to six weeks after exposure, although in previously sensitized individuals symptoms may appear within days. The primary clinical features are intense nocturnal itching and the appearance of thin, grayish‑white tunnels (burrows) that terminate in a papule or vesicle. Burrows are most frequently observed on the interdigital spaces of the hands, wrists, elbows, axillae, waistline, and genital region; infants may also show lesions on the scalp, face, and palms. Secondary bacterial infection can develop from excoriation, leading to crusted lesions, erythema, and, in severe cases, impetigo or cellulitis. In immunocompromised hosts or individuals with prolonged untreated disease, a hyperkeratotic form known as crusted scabies may arise, characterized by thickened plaques, extensive scaling, and a high mite burden.
Diagnosis relies on direct examination of skin scrapings or adhesive tape extracts placed on a microscope slide. Visualization of mites, eggs, or fecal pellets confirms infection. Dermoscopy can reveal the classic “delta wing” sign, a triangular structure representing the anterior portion of the mite within its burrow. Serologic tests are not routinely used, and differential diagnosis includes allergic dermatitis, papular urticaria, and other parasitic infestations.
Effective management combines topical acaricides, systemic therapy, and environmental control. Recommended regimens include:
- Permethrin 5 % cream applied from the neck down (or over the entire body in infants) and left on for eight to fourteen hours before washing; repeat after seven days.
- Ivermectin administered orally at 200 µg/kg as a single dose, repeated after 7–14 days; higher or additional doses may be required for crusted scabies.
- Benzyl benzoate 25 % lotion applied similarly to permethrin, with a second application after 24 hours; caution advised for children under two years.
- Sulfur ointment 5–10 % used for infants and pregnant women; applied nightly for three consecutive nights.
- Crotamiton 10 % cream as an alternative; applied twice daily for five days.
All close contacts, regardless of symptom presence, should receive prophylactic treatment with the same regimen to prevent reinfestation. Bedding, clothing, and towels must be washed in hot water (≥ 60 °C) and dried on high heat; items unable to be laundered should be sealed in plastic for at least 72 hours. Environmental decontamination of living spaces reduces the risk of recurrence. Follow‑up examination after the final treatment confirms eradication; persistent lesions warrant repeat microscopy and possible escalation to oral ivermectin or combination therapy.