Where do lice originate in the head? - briefly
Lice begin their life cycle as eggs attached to hair shafts close to the scalp, where they hatch and mature. The infestation therefore originates from these nits situated on the head.
Where do lice originate in the head? - in detail
Head lice (Pediculus humanus capitis) are obligate ectoparasites that survive only on the human scalp. Adult females deposit oval eggs, commonly called nits, on hair shafts within a few millimetres of the skin. The attachment point provides the embryo with constant warmth and access to blood meals, establishing the initial population on the host.
Transmission occurs primarily through direct head‑to‑head contact. Secondary routes include sharing combs, hats, pillows, or other objects that have recently touched an infested scalp. The parasite cannot develop off a human host; therefore, all new infestations originate from an existing carrier.
The developmental sequence consists of three stages:
- Egg (nit): incubation period 7–10 days, firmly glued to hair.
- Nymph: three molts over 3–4 days, each stage requires a blood meal.
- Adult: lifespan 7–10 days, capable of laying up to eight eggs per day.
Environmental conditions on the scalp—temperature around 34 °C, relative humidity 50–70 %, and the presence of sebum—facilitate egg adhesion and nymph development. These factors define the precise microhabitat where lice emerge and multiply.