What are lice and how do they appear? - briefly
Lice are small, wing‑less insects that live on the blood of humans or animals, feeding by piercing the skin with their mouthparts. Infestations arise when eggs (nits) hatch on hair shafts and the newly emerged lice spread through direct contact or shared personal items.
What are lice and how do they appear? - in detail
Lice are obligate ectoparasites that live on the skin, hair, or feathers of warm‑blooded hosts. They belong to the order Phthiraptera and are divided into three major groups: head lice (Pediculus humanus capitis), body lice (Pediculus humanus corporis), and pubic lice (Pthirus pubis). All species are wingless, dorsoventrally flattened, and range from 2 to 4 mm in length. Their bodies are covered with tiny claws adapted for grasping hair shafts or feathers.
The life cycle consists of three stages: egg (nit), nymph, and adult. Females lay eggs near the base of hair or feather shafts; each egg is cemented to the substrate and hatches in 7–10 days. Nymphs undergo three molts over 9–12 days before reaching maturity. Adults survive for 30 days on a host and require frequent blood meals, which they obtain by piercing the skin with specialized mouthparts.
Infestation occurs through direct contact with an infested individual or via contaminated personal items such as combs, clothing, or bedding. Body lice are transmitted primarily through shared clothing and poor hygiene, while head and pubic lice spread by close head-to-head or sexual contact. The following factors increase the risk of acquisition:
- Crowded living conditions
- Limited access to laundering facilities
- Frequent head-to-head interaction (e.g., schools, sports)
- Unprotected sexual activity
Clinical signs include persistent itching, visible nits attached to hair shafts, and the presence of live insects. Scratching may lead to secondary bacterial infection. Diagnosis relies on visual inspection of the scalp, body hair, or genital area, looking for adult lice and eggs within 1 mm of the skin surface.
Effective management combines mechanical removal and chemical treatment. Recommended steps are:
- Use a fine-toothed comb to detach nits and adult lice.
- Apply a topical pediculicide containing permethrin 1 % or dimethicone, following label directions.
- Wash clothing, bedding, and personal items in hot water (≥ 60 °C) or seal them in airtight bags for two weeks to kill any surviving stages.
- Re‑examine the host after seven days and repeat treatment if live lice are detected.
Prevention strategies focus on minimizing head-to-head contact, maintaining personal hygiene, and regularly cleaning personal items that may harbor eggs. Regular screening in high‑risk environments, such as schools and shelters, helps identify infestations early and limits spread.