What are lice in hair? - briefly
Lice are tiny, wingless ectoparasites of the order Phthiraptera that live on the human scalp, clinging to hair shafts and feeding on blood from the skin. Infestations cause itching and are usually managed with topical insecticides or thorough combing to remove the insects and their eggs.
What are lice in hair? - in detail
Head lice (Pediculus humanus capitis) are tiny, wingless insects that live on the scalp and feed on human blood. Adult specimens measure 2–4 mm, are tan to gray, and have six legs adapted for grasping hair shafts. Their life cycle comprises three stages: egg (nit), nymph, and adult. Eggs are cemented to hair close to the scalp, hatch in 7–10 days, and nymphs mature into reproductive adults after another 7–10 days. An adult female can lay 5–10 eggs per day, producing up to 150 eggs over her lifespan of about 30 days.
Transmission occurs through direct head-to-head contact, which enables lice to crawl from one host to another. Indirect spread via personal items—combs, hats, bedding, or clothing—has a lower probability because lice cannot survive long off a human host; they typically die within 24–48 hours without blood. Infestation prevalence peaks among school‑age children, especially in crowded or low‑hygiene environments, but adults may also be affected.
Clinical manifestations include intense itching caused by an allergic reaction to lice saliva, irritation of the scalp, and the presence of visible nits attached to hair shafts. Scratching can lead to secondary bacterial infection. Diagnosis relies on visual inspection: live lice appear as moving specks, while nits are oval, firm, and positioned within 1 cm of the scalp. A systematic “wet‑comb” method—applying a conditioner, then combing with a fine‑toothed lice comb from the scalp outward—enhances detection.
Management strategies consist of chemical and mechanical approaches. Over‑the‑counter pediculicides contain pyrethrins, permethrin, or dimethicone; they must be applied according to label directions, repeated after 7–10 days to kill newly hatched nits, and used with caution in infants and pregnant women. Mechanical removal involves daily wet combing for two weeks, which eliminates both lice and eggs without pharmacologic exposure. Environmental control includes washing bedding, clothing, and personal items in hot water (≥ 60 °C) or sealing them in plastic bags for two weeks to starve residual insects.
Prevention focuses on minimizing head contact, avoiding sharing personal grooming tools, and conducting regular scalp checks in settings where outbreaks are common. Prompt treatment of identified cases reduces transmission risk and limits the duration of infestation.