How do lice spread from person to person? - briefly
Lice move from one host to another mainly via direct head‑to‑head contact or by sharing items such as hats, combs, or hair accessories. They do not jump or fly; transmission occurs only when the insects or their eggs are physically transferred.
How do lice spread from person to person? - in detail
Lice move between hosts primarily through physical contact. When an infested head touches another, nymphs and adult insects crawl onto the new scalp within seconds. This direct head‑to‑head interaction accounts for the majority of new cases in schools, camps, and households.
Secondary pathways involve personal objects that contact hair. Items such as combs, brushes, hats, helmets, scarves, hair ties, and headphones can retain live lice or viable eggs. If these objects are exchanged or placed on another person’s head without thorough cleaning, the insects can transfer.
Environmental reservoirs play a minor role. Lice survive off the human body for only a short period—typically 24–48 hours—so contaminated bedding, upholstered furniture, or carpet fibers may pose a risk if a person’s head rests on them shortly after an infested individual.
Key factors that increase the likelihood of transmission include:
- Close, prolonged contact among children or adults.
- Sharing of headgear or grooming tools without disinfection.
- Overcrowded living conditions that limit personal space.
- Inadequate awareness of early signs, leading to delayed treatment.
The life cycle of the parasite reinforces rapid spread. Eggs hatch in 7–10 days, producing nymphs that mature to reproductive adults within another 7–10 days. Each adult can lay 5–10 eggs per day, creating a potential exponential increase in the population if unchecked.
Effective control relies on interrupting these routes: immediate removal of head‑to‑head contact, regular washing of personal items at temperatures above 50 °C, and prompt treatment of infested individuals with approved pediculicides followed by thorough combing to eliminate remaining lice and eggs.