How can lice infest a person's head? - briefly
Lice spread through direct head‑to‑head contact or by sharing personal items—hats, combs, headphones—that carry live insects or attached eggs. The parasites lay nits on hair shafts, which hatch within about a week, allowing the infestation to develop rapidly.
How can lice infest a person's head? - in detail
Lice reach a human scalp primarily through direct head‑to‑head contact. When an infested individual brushes, combs, or rests their hair against another’s, adult females deposit eggs (nits) on hair shafts close to the skin. The eggs hatch in 7–10 days, releasing nymphs that begin feeding on blood within hours. Nymphs mature into reproductive adults after another 7–10 days, completing the cycle in about three weeks.
Secondary routes include sharing personal items that contact hair, such as combs, brushes, hats, helmets, hair accessories, and bedding. Lice cannot survive more than 48 hours off a host, so transmission via contaminated objects requires recent use. Crowded environments—schools, daycare centers, camps—facilitate frequent close contact, increasing infestation risk.
Factors that promote colonization are:
- Warm, humid conditions that prolong lice activity.
- Dense or long hair that provides a stable substrate for egg attachment.
- Infrequent hair washing, which does not eliminate lice but may reduce their numbers.
- Lack of regular inspection, allowing early stages to go unnoticed.
Once established, lice feed several times a day, each bite causing irritation and possible secondary infection from scratching. The population expands rapidly because each female lays 5–10 eggs daily, totaling up to 300 eggs over her lifespan.
Effective control requires:
- Immediate removal of all visible nits using a fine‑toothed comb.
- Treatment of the entire head with an approved pediculicide, following the product’s instructions for repeat application after 7–10 days to kill newly hatched nymphs.
- Laundering clothing, bedding, and personal items in hot water (≥60 °C) or sealing them in plastic bags for two weeks to kill any surviving insects.
- Regular head checks for at least two weeks after treatment to confirm eradication.