How does a person become infected with lice? - briefly
Lice are transferred mainly by direct head‑to‑head contact or by sharing items such as combs, hats, or pillows that have recently touched an infested scalp. Poor hygiene does not cause infestation, but crowded settings increase the likelihood of transmission.
How does a person become infected with lice? - in detail
Lice infestations begin when viable eggs or nymphs reach a human scalp. The most common pathway is direct head‑to‑head contact, which transfers mobile lice from one person’s hair to another’s. This mode accounts for the majority of cases in schools, day‑care centers, and sports teams where close physical interaction is frequent.
Secondary pathways involve shared personal items. Objects that contact hair—such as combs, brushes, hats, scarves, hair clips, helmets, pillowcases, and bedding—can retain live insects or recently hatched nymphs. When another individual uses the contaminated item, lice may crawl onto the new host.
Environmental exposure plays a minor role. Lice survive only a short time off a human host (generally less than 24 hours). Nevertheless, heavily infested surfaces, such as upholstered furniture or classroom chairs, can serve as temporary reservoirs, allowing transfer if a person’s scalp contacts the surface shortly after infestation.
Risk factors that increase susceptibility include:
- Close‑quarter living conditions (dormitories, camps, shelters).
- Frequent sharing of headgear or grooming tools.
- Lack of regular hair hygiene checks, especially in children.
- Presence of a current infestation in a household member.
The life cycle reinforces transmission. Adult females lay 6–10 eggs (nits) per day, attaching them to hair shafts near the scalp. Eggs hatch in 7–10 days, releasing nymphs that mature into reproductive adults within another 9–12 days. During this period, each stage can move to a new host through the mechanisms described above.
Preventive measures focus on minimizing direct contact, avoiding the exchange of hair‑related items, and promptly treating identified infestations to interrupt the reproductive cycle. Early detection and isolation of affected individuals reduce the chance of spread within a community.