How are lice transmitted and how can they be eliminated? - briefly
Lice spread mainly through direct head-to-head contact or sharing personal items such as hats, combs, and bedding. Effective removal combines thorough combing with a fine-toothed lice comb and the application of approved topical insecticides, followed by washing clothing and linens in hot water.
How are lice transmitted and how can they be eliminated? - in detail
Lice spread primarily through direct physical contact between individuals. Head lice transfer when a head touches another head, allowing mobile insects to crawl onto a new host. Indirect transfer occurs when personal items such as combs, hairbrushes, hats, scarves, pillows, or bedding are shared without proper cleaning; eggs attached to these objects can hatch on a new person’s scalp. Body lice, which inhabit clothing seams, move to a fresh host when contaminated garments are exchanged or worn by multiple people. Pubic lice, also known as crab lice, transmit mainly through sexual contact, although sharing towels or bedding can also facilitate transfer.
The life cycle influences transmission dynamics. Adult females lay eggs (nits) firmly cemented to hair shafts or fibers, where they remain viable for up to a week. Nits hatch into nymphs, which mature into reproductive adults within 7–10 days. This rapid development means that a single infestation can expand quickly if untreated.
Elimination requires a multi‑step approach:
- Mechanical removal: Use a fine‑tooth nit comb on damp hair, working from scalp outward, to extract live insects and detached nits. Repeat daily for at least one week.
- Topical pediculicides: Apply agents such as 1 % permethrin, 0.5 % malathion, spinosad, or dimethicone according to label directions. Ensure thorough coverage of the scalp and hair shafts; leave the product for the recommended period before rinsing.
- Oral therapy: In cases of resistant infestations, a single dose of ivermectin (200 µg/kg) can be administered, with a repeat dose after 7 days if necessary.
- Environmental control: Wash clothing, bedding, and towels in water ≥ 60 °C or seal them in a plastic bag for 72 hours to kill dormant stages. Vacuum upholstered furniture and carpets to remove stray nits.
- Follow‑up treatment: Apply a second round of topical medication 7–10 days after the first to eradicate newly emerged lice that survived the initial application.
Effective management combines personal hygiene, proper use of approved insecticidal products, and rigorous cleaning of contaminated items. Prompt implementation of these measures curtails spread and resolves the infestation.