How dangerous are lice and nits? - briefly
They cause itching and can lead to secondary bacterial infection. They do not transmit serious diseases.
How dangerous are lice and nits? - in detail
Head lice (Pediculus humanus capitis) and their eggs pose health concerns primarily through direct skin irritation and secondary bacterial infection. The insects feed on blood, causing localized itching that can lead to scratching, which opens micro‑abrasions. These breaches allow opportunistic bacteria such as Staphylococcus aureus or Streptococcus pyogenes to colonise, potentially resulting in impetigo or cellulitis. While systemic illness is rare, vulnerable groups—young children, individuals with compromised immunity, and those with eczema—experience heightened risk of severe skin reactions.
Transmission occurs via close head‑to‑head contact, shared personal items (combs, hats, helmets) and, less commonly, through contaminated bedding or upholstery. Infestations spread quickly in environments where close contact is routine, such as schools, daycare centers, and sports teams. The life cycle—from egg (nit) to adult—lasts about three weeks; nits hatch in 7–10 days, and mature lice can reproduce within a further 5–7 days, sustaining the population if untreated.
Treatment challenges include:
- Resistance to common insecticides (permethrin, pyrethrins) observed in many regions, necessitating alternative agents (malathion, spinosad) or mechanical removal.
- Incomplete eradication of nits, which remain attached to hair shafts and may hatch after a single treatment, requiring repeat application or thorough combing.
- Potential toxicity of chemical pediculicides, especially in children under two years, prompting recommendations for non‑chemical methods (wet combing, silicone‑based lotions) as first‑line options.
Psychosocial impact, though not a direct physiological danger, contributes to stigma, absenteeism from school or work, and increased health‑care costs. Early identification and comprehensive management—combining chemical or physical treatment with environmental decontamination (washing bedding at ≥60 °C, vacuuming upholstery)—reduce both medical complications and the broader burden on families and institutions.