Why do lice keep appearing? - briefly
«Lice» persist because their nits resist treatment, spread through direct head‑to‑head contact, and quickly reappear from untreated carriers or contaminated objects. Effective control requires simultaneous treatment of all affected persons and regular removal of eggs.
Why do lice keep appearing? - in detail
Lice infestations persist because the insects complete their life cycle rapidly, with eggs (nits) hatching in 7–10 days and adults reproducing every 24–48 hours. Female lice lay up to 10 eggs per day, ensuring a constant supply of viable offspring.
Resistance to commonly used insecticidal shampoos reduces treatment efficacy. Mutations in lice populations diminish the toxicity of pyrethrins and permethrin, allowing survivors to repopulate hair after a single application. Additionally, eggs are protected by a cement‑like shell that resists many chemical agents, so incomplete eradication leaves a reservoir for re‑infestation.
Human practices contribute significantly. Inadequate treatment—such as applying a product for less than the recommended duration—fails to kill all stages. Sharing combs, hats, or bedding transfers live lice and nits between individuals. Failure to launder clothing and linens at temperatures above 50 °C permits eggs to survive and hatch later.
Crowded environments, especially schools and daycare centers, facilitate rapid spread. Close physical contact and frequent head‑to‑head interactions increase transmission opportunities. Limited access to effective treatment in some communities exacerbates the problem.
Effective control requires a multi‑step approach:
- Apply an approved pediculicide according to label instructions, ensuring contact time is met.
- Repeat treatment after 7–10 days to target newly hatched nits.
- Use a fine‑toothed nit comb on wet hair to remove eggs mechanically.
- Wash clothing, bedding, and personal items in hot water or seal them in plastic bags for two weeks to kill any surviving lice.
- Educate caregivers and staff about early detection and proper hygiene practices.
Consistent implementation of these measures interrupts the reproductive cycle, reduces resistance pressure, and limits opportunities for re‑introduction, thereby decreasing the frequency of recurring infestations.