What causes head lice? - briefly
Head lice result from infestation by the parasite Pediculus humanus capitis, which transfers primarily through direct head‑to‑head contact or sharing personal items such as combs, hats, and bedding. Poor hygiene does not cause lice, but crowded settings and close physical interaction increase transmission risk.
What causes head lice? - in detail
Head lice (Pediculus humanus capitis) spread primarily through direct head-to-head contact. The insects cannot jump or fly; they move by crawling and cling to hair shafts using clawed legs.
Key transmission routes include:
- Close personal interaction – sharing a bed, couch, or any situation where heads touch for a prolonged period.
- Shared personal items – combs, brushes, hats, scarves, headphones, helmets, or hair accessories that have recently touched an infested scalp.
- Crowded environments – schools, daycare centers, camps, and shelters where many individuals are in close proximity.
- Infrequent hygiene practices – irregular washing of hair or neglecting to clean personal items does not prevent infestation but can increase the likelihood of sustained presence.
Biological factors that facilitate infestation:
- Temperature and humidity – lice thrive in warm, moist conditions typical of the human scalp.
- Hair characteristics – longer hair provides a larger surface area for egg attachment; dense hair may reduce detection.
- Age group – children aged 3‑11 are most susceptible due to frequent close contact during play.
Preventive measures focus on minimizing contact with contaminated hair and objects, regular inspection of scalp and hair, and prompt treatment of identified cases to interrupt the life cycle. Effective treatment eliminates adults, nymphs, and eggs, reducing the risk of re‑infestation from residual lice on personal belongings.