What do lice look like and how are they treated? - briefly
Lice are tiny, wing‑less insects about 2–4 mm in length, with a flattened, elongated body, six short legs adapted for grasping hair shafts, and a gray‑brown, translucent appearance that makes their eggs visible near the scalp. Effective treatment combines an approved pediculicide shampoo or lotion with meticulous combing to extract nits, followed by a repeat application after 7–10 days to eradicate any newly hatched insects.
What do lice look like and how are they treated? - in detail
Lice are obligate ectoparasites that feed on human blood. Adult head‑lice (Pediculus humanus capitis) measure 2–4 mm in length, have a flattened, elongated body, and display a gray‑white coloration that darkens after a blood meal. Their three pairs of legs are short, stout, and equipped with claws that grip hair shafts. Nymphs resemble adults but are half the size and lack fully developed claws. Eggs (nits) are oval, 0.8 mm long, and firmly attached to the base of hair strands with a cement‑like secretion; they appear as creamy or yellowish ovals and can be mistaken for dandruff.
Effective eradication requires a two‑step approach: immediate removal of the insects and prevention of re‑infestation. Recommended measures include:
- Mechanical removal: Use a fine‑toothed comb on wet, conditioned hair to extract live lice and nits; repeat every 2–3 days for two weeks.
- Topical pediculicides: Apply products containing permethrin (1 %) or pyrethrin combined with piperonyl butoxide; follow label directions for exposure time and repeat treatment after 7–10 days to target newly hatched nits.
- Alternative agents: Dimethicone lotion (silicone‑based) suffocates lice without neurotoxic action; ivermectin 0.5 % lotion offers a single‑application option for resistant cases.
- Oral therapy: Single‑dose ivermectin (200 µg/kg) is reserved for severe or refractory infestations; contraindicated in pregnancy and children under 15 kg.
- Environmental control: Wash bedding, clothing, and personal items in hot water (≥ 60 °C) or seal in plastic bags for two weeks; vacuum carpets and upholstery to remove fallen nits.
Regular inspection of the scalp, especially behind the ears and at the nape, is essential to confirm treatment success. If live lice persist after two treatment cycles, consider resistance testing and alternative pharmacologic options.