After how long do lice become apparent after infection? - briefly
Lice infestations usually become visible within 7‑10 days after exposure, when nits hatch and the insects begin feeding. Early signs include itching and the appearance of live lice or eggs on hair shafts.
After how long do lice become apparent after infection? - in detail
Lice eggs (nits) hatch within 7–10 days after being laid on a host’s hair shaft. The first nymphs emerge at this stage and require an additional 5–7 days to mature into reproductive adults. Visible signs typically appear when the population reaches a few dozen insects, which occurs around 10–14 days after the initial contact with an infested person or contaminated objects.
Observable indicators include:
- Itching caused by the bite of feeding lice; the sensation often intensifies after the second or third week.
- Live lice moving on the scalp or attached near the hair roots; detection becomes reliable once adult numbers exceed five to ten per square inch.
- Nits attached firmly to hair shafts close to the scalp; they are most noticeable after the eggs have been laid and before they hatch, roughly a week after infestation.
Factors influencing the onset of symptoms:
- Infestation size – a small initial load may delay detection by several days.
- Host sensitivity – individuals with heightened skin reactions experience itching sooner.
- Hair length and type – longer hair provides more surface area for egg deposition, potentially accelerating observable nits.
In practice, most cases are diagnosed between the ninth and fifteenth day post‑exposure, when adult lice and nits are readily identifiable during a scalp examination. Early detection relies on meticulous visual inspection and awareness of itching patterns, especially in environments where close contact is common.