What are lice on hair? - briefly
Lice are small, wingless insects that inhabit the human scalp and consume blood. They deposit eggs, called nits, which cling to hair shafts and can cause itching and irritation.
What are lice on hair? - in detail
Head lice (Pediculus humanus capitis) are tiny, wingless insects that live on the human scalp and feed on blood. Adults measure 2–4 mm, are gray‑brown, and have six legs adapted for grasping hair shafts. Nymphs resemble adults but are smaller and develop through three molts before reaching maturity.
The life cycle proceeds as follows:
- Eggs (nits): Oval, cemented to the base of hair strands near the scalp; hatch in 7–10 days.
- Nymphs: Emerging larvae feed immediately; each molt occurs roughly every 2 days.
- Adults: Live 30 days on a host, laying 5–10 eggs per day; may survive several days off a host.
Infestation produces itching, irritation, and visible nits. Secondary bacterial infection can arise from scratching. Diagnosis relies on visual inspection of live lice or attached nits within 1 cm of the scalp.
Effective control measures include:
- Chemical pediculicides: 1% permethrin or 0.5% malathion, applied according to label directions.
- Mechanical removal: Fine‑toothed combs used on wet hair to extract lice and nits.
- Environmental decontamination: Washing bedding, clothing, and personal items in hot water (≥ 60 °C) or sealing them in plastic bags for two weeks.
- Repeated treatment: A second application 7–10 days after the first to eliminate newly hatched nits.
Prevention focuses on limiting head-to-head contact, avoiding sharing personal items such as combs or hats, and conducting regular scalp checks in settings where outbreaks are common.