How do lice initially infest a person? - briefly
Lice reach a new host mainly through direct head‑to‑head contact, which deposits adult insects onto the scalp’s hair shafts. They can also be transferred via contaminated personal items such as combs, hats, or bedding that have recently housed an infestation.
How do lice initially infest a person? - in detail
Lice begin their presence on a human host through direct contact with an already infested individual. A female adult attaches to the scalp, then secures her eggs (nits) to hair shafts within a centimeter of the skin using a cement‑like secretion. The eggs hatch in about seven days, releasing nymphs that immediately seek a blood meal. Nymphs mature after three to four molts, becoming reproductive adults in roughly ten days.
Transmission pathways include:
- Head‑to‑head contact during play, sports, or close personal interaction; this provides the quickest route because lice move readily across hair.
- Shared personal items such as combs, brushes, hats, helmets, hair accessories, and pillowcases; lice can survive off the scalp for 24–48 hours, allowing transfer when items are exchanged.
- Environmental exposure in densely populated settings (schools, camps) where contaminated bedding or upholstery may harbor lice for short periods.
The infestation process relies on several biological cues:
- Thermal gradient: lice are attracted to the warmth of the scalp.
- Carbon dioxide: exhaled CO₂ signals a potential blood source.
- Vibrations: movement of hair fibers indicates a living host.
Once on a new host, an adult louse locates a suitable oviposition site, deposits eggs, and the cycle repeats. Female lice can lay 5–8 eggs per day, producing a population that expands rapidly if untreated.