How do lice appear and what influences them? - briefly
Lice infestations start when adult females deposit eggs («nits») on hair shafts, which hatch into nymphs that mature within days. Their prevalence is driven by close personal contact, infrequent head washing, and warm, humid conditions.
How do lice appear and what influences them? - in detail
Lice infestations begin when female insects deposit eggs, called nits, on hair shafts close to the scalp. The eggs hatch within 7–10 days, releasing nymphs that mature after three molts, typically within another 7 days. Adult lice survive up to 30 days, feeding exclusively on blood and reproducing continuously, which sustains the colony.
Several conditions contribute to the development and spread of lice:
- Direct head‑to‑head contact, the primary transmission route in schools, daycare centers, and sports teams.
- Sharing personal items such as combs, hats, headphones, or bedding, which can transfer viable eggs or live insects.
- High population density, where crowded living environments increase the likelihood of accidental contact.
- Inadequate hygiene practices, including infrequent hair washing, create a favorable environment for egg adhesion and survival.
- Warm, humid climates accelerate nymph development and prolong adult lifespan, enhancing reproductive output.
- Genetic factors in the host, such as hair texture and scalp oil composition, may affect attachment success, although evidence remains limited.
Control measures focus on interrupting the life cycle: mechanical removal of nits with fine‑toothed combs, application of approved pediculicidal agents that target both adults and emerging nymphs, and thorough laundering of clothing and bedding at temperatures above 50 °C. Re‑inspection after 7–10 days is essential to eliminate any newly hatched insects before they reach reproductive maturity. Regular education about transmission routes and prompt treatment of identified cases reduce the overall prevalence within communities.