How do lice infest the head? - briefly
Female head lice secure their eggs (nits) to hair shafts close to the scalp, where they hatch into nymphs that feed on blood and reproduce quickly. Infestation spreads mainly through direct head‑to‑head contact or by sharing combs, hats, and other personal items.
How do lice infest the head? - in detail
Head lice colonize the scalp through a series of well‑defined steps. An adult female deposits several eggs (nits) near the hair shaft, usually within 1 cm of the scalp. The adhesive secreted by the female hardens, anchoring each egg to the hair. Over the next 7–10 days, the nits incubate; temperature and humidity near the scalp accelerate embryonic development.
When the nymphs hatch, they remain on the hair surface and begin feeding on blood from the scalp. Their mouthparts pierce the epidermis, drawing small amounts of blood several times a day. This feeding provides the energy needed for rapid growth. Nymphs molt three times before reaching adult size, a process lasting about 9 days.
Reproduction resumes once females mature. Each adult female can lay 6–10 eggs per day, producing up to 100 eggs during her lifespan of approximately 30 days. The high reproductive rate ensures a swift increase in population if unchecked.
Transmission occurs primarily through direct head‑to‑head contact, which transfers mobile lice and their eggs. Indirect spread via objects such as hats, combs, or bedding is possible but less common because lice require a live host for survival.
Key environmental factors influencing infestation include:
- Warm, humid conditions that favor egg viability and nymph development.
- Crowded settings where close contact is frequent (e.g., schools, camps).
- Inadequate personal hygiene practices that allow lice to remain undetected.
Detection relies on visual inspection of the hair and scalp. Live lice appear as small, wingless insects 2–4 mm long, gray‑brown in color. Nits are oval, white, and firmly attached to the hair shaft. A systematic combing with a fine‑toothed lice comb, performed on dry hair, reveals both stages.
Effective control combines mechanical removal (wet combing to extract lice and nits) with topical treatments that disrupt the nervous system of the insects. Re‑treatment after 7–10 days eliminates newly hatched nymphs that survived the initial application. Continuous monitoring for at least 4 weeks prevents resurgence.