What are white lice? - briefly
White lice are the newly hatched, translucent nymphs of the human head‑lice (Pediculus humanus capitis), which appear pale until they mature. They remain attached to hair shafts near the scalp and feed on blood in the same manner as adult lice.
What are white lice? - in detail
White lice belong to the family Pediculidae and are classified as Pediculus humanus var. capitis when they infest the human scalp. The term “white” refers to the pale coloration of the nymphal stages and the adult’s translucent exoskeleton, which appears whitish when detached from the host.
Morphologically, white lice are small, wing‑less insects measuring 2–4 mm in length. Their bodies consist of a head with compound eyes, antennae, and mouthparts adapted for piercing skin and sucking blood. The abdomen bears six pairs of legs, each ending in claws that grip hair shafts. Development proceeds through three nits (egg) stages, three nymphal instars, and the mature adult, completing the cycle in approximately 21 days under optimal temperature (30 °C) and humidity (70 %).
The primary habitat is the human scalp, where lice lay eggs firmly attached to hair shafts near the scalp surface. They survive exclusively on human blood; no known animal reservoirs exist. Infestation density can reach dozens of individuals per square centimeter, leading to intense itching caused by allergic reactions to saliva.
Clinical effects include pruritus, secondary bacterial infection from scratching, and, in severe cases, anemia due to chronic blood loss. Diagnosis relies on visual inspection of live insects and the presence of nits attached at a 45° angle to hair strands.
Effective management combines mechanical and chemical measures:
- Manual removal: fine‑toothed lice combs used on wet hair after applying a conditioning agent to immobilize nits.
- Topical pediculicides: permethrin 1 % lotion applied to the scalp for 10 minutes, repeated after 7 days to eliminate newly hatched nits.
- Oral ivermectin: single dose of 200 µg/kg for resistant infestations, with a repeat dose after 7 days if required.
- Environmental control: washing bedding, clothing, and personal items in hot water (>50 °C) or sealing them in airtight bags for two weeks.
Prevention focuses on avoiding head‑to‑head contact, not sharing combs or hats, and regular screening of close contacts during outbreaks.