What are lice and how can they be dealt with? - briefly
Lice are tiny, wingless parasites that inhabit human scalp hair and feed on blood. Control relies on applying a pediculicide shampoo or lotion, thoroughly combing out nits, and repeating the treatment after 7–10 days to eradicate any newly hatched insects.
What are lice and how can they be dealt with? - in detail
Lice are obligate ectoparasites that feed exclusively on human blood. Three species affect humans: Pediculus humanus capitis (head lice), Pediculus humanus corporis (body lice) and Pthirus pubis (pubic lice). Adult head lice measure 2–4 mm, have six legs, and lay 6–10 eggs (nits) per day, attaching them to hair shafts near the scalp. Nits hatch in 7–10 days, releasing nymphs that mature in another 9–12 days. Body lice reside in clothing seams and move to the skin to feed, while pubic lice inhabit coarse hair in the genital region.
Transmission occurs through direct head‑to‑head contact, sharing personal items (combs, hats), or, for body lice, through infested clothing and poor hygiene. Infestation manifests as itching caused by allergic reactions to saliva, visible live insects or nits, and secondary skin lesions from scratching.
Effective management combines chemical, mechanical, and environmental strategies:
- Topical pediculicides: Permethrin 1 % lotion, pyrethrin‑based products, or malathion 0.5 % applied to dry hair for 10 minutes, then rinsed. Resistance may require alternative agents such as ivermectin 0.5 % lotion or benzyl alcohol 5 % lotion.
- Nit removal: Fine‑toothed nit combs used on wet, conditioned hair for 5–10 minutes, repeated every 2–3 days until no nits remain.
- Oral medications: Ivermectin 200 µg/kg single dose for resistant cases; contraindicated in pregnancy and children under 15 kg.
- Clothing and bedding: Wash at ≥60 °C or seal in airtight bags for 2 weeks; dry‑clean items not washable.
- Environmental cleaning: Vacuum carpets and upholstered furniture; discard hair accessories that cannot be decontaminated.
Prevention focuses on minimizing head‑to‑head contact, avoiding sharing personal grooming tools, and maintaining regular hair inspections in schools or group settings. Prompt detection and comprehensive treatment reduce the risk of ongoing transmission and complications.