How can you tell if there are no lice? - briefly
«Absence of lice is confirmed by a thorough scalp examination under bright light, ensuring no live insects, nits attached within ¼ inch of the hair shaft, or recent bites are observed».
How can you tell if there are no lice? - in detail
To confirm that a scalp is free of Pediculus humanus capitis, follow a systematic assessment that combines visual examination, mechanical detection, and contextual verification.
A thorough visual check should be performed under bright lighting. Examine the hair and scalp in sections, starting at the crown and moving outward. Look for live insects, which are tan to brown, about 2–4 mm long, and move quickly when disturbed. Also search for empty egg shells (nits) that are firmly attached to hair shafts within ¼ inch of the scalp; their presence indicates recent infestation.
Mechanical detection enhances reliability. Use a fine-toothed lice comb, preferably with 0.2 mm spacing, on dry hair. Comb from the scalp outward, wiping the comb on a white surface after each pass. Repeat the process several times per section. The discovery of any live louse or viable nit confirms infestation; the absence of such findings after multiple thorough passes strongly suggests eradication.
Contextual factors support the conclusion. Verify that any prescribed or over‑the‑counter treatment has been applied according to the label’s schedule, including a second dose typically 7–10 days after the first. Ensure that all household items (bedding, clothing, hats) have been washed in hot water (≥ 60 °C) or sealed in plastic bags for two weeks to eliminate residual eggs. Confirm that no close contacts exhibit symptoms, as reinfestation can occur quickly.
A concise checklist for confirming the absence of lice:
- Bright‑light visual inspection of entire scalp and hair.
- Use of a fine‑toothed comb on dry hair, multiple passes per section.
- No live insects or viable nits detected after thorough combing.
- Completion of recommended treatment regimen, including follow‑up dose.
- Decontamination of personal items and environment.
- Absence of symptoms in close contacts for at least two weeks.
When all items on the list are satisfied, the likelihood of remaining infestation is negligible. Continuous monitoring for a fortnight after treatment provides additional assurance.