What is a scabies mite and how is it treated?

What is a scabies mite and how is it treated? - briefly

The scabies mite (Sarcoptes scabiei) is a microscopic, burrowing arthropod that inhabits the superficial skin layer, producing intense itching and a characteristic rash. Treatment relies on a single or repeated application of a topical scabicidal agent such as 5 % permethrin cream, while oral ivermectin is used for resistant or extensive infestations.

What is a scabies mite and how is it treated? - in detail

The parasite responsible for scabies is a microscopic arthropod of the species Sarcoptes scabiei var. hominis. Adult females are oval, approximately 0.3–0.4 mm long, and burrow into the superficial layers of the epidermis to lay eggs. Each female can produce 10–30 eggs during a 4‑week lifespan; the eggs hatch in 3–4 days, releasing larvae that mature into nymphs and then adults within another 10–14 days. Transmission occurs through prolonged skin‑to‑skin contact, though contaminated clothing or bedding can also spread the mite in crowded environments.

Clinical manifestation results from the mite’s activity and the host’s immune response. Primary lesions are linear or serpiginous tracks representing burrows, often located on wrists, interdigital spaces, elbows, waistline, and genitalia. Intense pruritus intensifies at night and may be accompanied by papules, vesicles, or nodules. Secondary bacterial infection can develop when scratching breaks the skin barrier.

Diagnostic confirmation relies on:

• Direct microscopic examination of skin scrapings, revealing mites, eggs, or fecal pellets.
• Dermoscopy, showing the characteristic “delta wing” sign (the mite’s head at the end of a burrow).
• Clinical assessment of typical distribution and symptom pattern, especially in outbreak settings.

Therapeutic regimens focus on eradicating the parasite and preventing reinfestation:

1. Topical scabicidal agents

   • Permethrin 5 % cream applied from the neck down (including scalp in infants) and left on for 8–14 hours before washing; repeat after 7 days to eliminate newly hatched mites.
   • Benzyl benzoate 10–25 % lotion applied similarly, though skin irritation is common.
   • Sulfur 5–10 % ointment for infants and pregnant women; requires overnight application for several consecutive nights.

2. Oral ivermectin

   • Single dose of 200 µg/kg body weight; a second dose administered 7 days later improves efficacy, particularly in crusted scabies or when topical treatment is impractical.
   • Adjusted dosing for children weighing less than 15 kg or for patients with hepatic impairment.

3. Adjunct measures

   • Wash all clothing, bedding, and towels used within the preceding 72 hours in hot water (≥50 °C) and dry on high heat; items that cannot be laundered should be sealed in plastic for at least 72 hours.
   • Treat household contacts simultaneously, regardless of symptom presence, to break transmission chains.
   • Apply moisturizers or low‑potency corticosteroids to alleviate inflammation and itching after scabicidal therapy.

Follow‑up evaluation occurs 2–4 weeks post‑treatment; persistent lesions may indicate treatment failure, resistance, or secondary infection and warrant repeat therapy or alternative agents. In immunocompromised patients or those with crusted scabies, combination therapy (topical plus oral ivermectin) and extended treatment courses are often necessary.

Overall, prompt identification, comprehensive treatment of patients and close contacts, and strict hygiene protocols constitute the most effective strategy for eliminating the infestation and preventing recurrence.