When are lice present? - briefly
Lice appear when a host offers a warm scalp and regular blood meals, typically after close personal contact or sharing items such as combs or hats. Infestations are most common in environments where these conditions are sustained.
When are lice present? - in detail
Lice infestations appear when adult females lay eggs on hair shafts close to the scalp. Eggs, or nits, hatch in 7‑10 days, releasing nymphs that mature after an additional 9‑12 days. The complete life cycle, from egg to reproducing adult, therefore requires roughly 2‑3 weeks under optimal temperature (30‑32 °C) and humidity conditions.
Key factors influencing the presence of lice include:
- Direct head‑to‑head contact, the primary transmission route.
- Shared personal items such as combs, hats, or helmets, which can transfer eggs or live insects.
- Environments with close physical proximity, for example schools, daycare centers, and camps.
- Warm, humid climates that accelerate development and increase survival rates.
- Inadequate hygiene practices, though cleanliness alone does not prevent infestation.
Population peaks typically occur during school terms, when children interact frequently. Seasonal variations are observed, with higher rates in late summer and early autumn, coinciding with the start of the academic year. Outbreaks may also follow periods of increased travel or large gatherings.
Effective detection relies on visual inspection of the scalp and hair for live lice and nits attached within 1 mm of the scalp. Prompt treatment, combined with washing of personal items at ≥ 60 °C or sealing them in plastic bags for 2 weeks, reduces the likelihood of re‑infestation. Continuous monitoring for 2‑3 weeks after treatment ensures that any newly hatched nymphs are identified and eliminated.