Why do lice keep reappearing on a child? - briefly
Lice reappear when viable eggs survive the first treatment or when the child is re‑exposed to infested persons or contaminated items such as hats, brushes, and bedding. Incomplete eradication, resistance to pediculicides, and close contact in homes or schools promote repeated infestations.
Why do lice keep reappearing on a child? - in detail
Head lice survive by clinging to hair shafts and feeding on blood several times a day. Their eggs (nits) are firmly attached near the scalp, and a single female can lay up to 10 eggs per day. Because nits hatch in 7‑10 days, any missed egg during treatment can produce a new generation within a week.
Repeated infestations arise from several common sources. Incomplete eradication is the most frequent cause; many over‑the‑counter products kill only adult lice, leaving nits untouched. Resistance to common insecticides, especially pyrethroids, reduces the efficacy of standard shampoos. Re‑exposure occurs when close contacts—classmates, siblings, caregivers—remain untreated, or when shared items such as hats, brushes, or bedding are not disinfected. Hair characteristics, such as length and thickness, can hinder thorough combing and nit removal. Finally, environmental reservoirs like upholstered furniture or carpets can harbor lice that crawl back onto the child.
Effective interruption of the cycle requires a multi‑step approach:
- Apply a pediculicide that is proven to kill both lice and nits; follow the label’s timing precisely.
- After the first treatment, repeat the application 7–10 days later to eliminate newly hatched lice.
- Use a fine‑toothed nit comb on wet hair for at least 10 minutes, repeating every 2–3 days for two weeks.
- Wash clothing, bedding, and towels used within the previous 48 hours in hot water (≥ 60 °C) and dry on high heat; items that cannot be laundered should be sealed in plastic for two weeks.
- Treat all household members and anyone with close physical contact, even if they show no signs of infestation.
- Avoid sharing personal items and discourage head‑to‑head contact during play.
Monitoring continues for four weeks after the final treatment. Inspect the scalp daily for live lice or viable nits; any detection warrants immediate retreatment. Consistent application of these measures reduces the likelihood of further recurrences.