What is the medical term for head lice? - briefly
The scalp‑infesting louse is medically termed Pediculus capitis (also referred to as Pediculus humanus capitis). It is a species of chewing lice in the order Phthiraptera.
What is the medical term for head lice? - in detail
The medical designation for head lice is Pediculus humanus capitis, a subspecies of the human louse that inhabits the scalp and hair shafts. It belongs to the order Phthiraptera, family Pediculidae, and is an obligate ectoparasite of Homo sapiens.
Pediculus humanus capitis is a small, wingless insect measuring 2–4 mm in length. The adult body is dorsally flattened, covered with fine hairs, and exhibits a tan to gray coloration. The head bears a pair of compound eyes, three-segmented antennae, and mandibles adapted for feeding on blood. The legs end in claws that grasp hair shafts, enabling rapid movement across the scalp.
The life cycle proceeds through three distinct stages:
- Egg (nit): Oval, cemented to the hair shaft near the scalp; incubation lasts 7–10 days.
- Nymph: Immature form undergoing three molts; each instar lasts 3–4 days.
- Adult: Fully developed, capable of laying 5–10 eggs per day; lifespan averages 30 days.
Reproduction is ovoviviparous; females retain eggs until they are ready to be deposited. A single female can generate a population of several hundred lice within a month under favorable conditions.
Diagnosis relies on visual identification of live insects, viable nits within 1 cm of the scalp, and characteristic itching caused by repeated blood feeding. Dermatoscopic examination enhances detection accuracy, especially in early infestations.
Effective management includes:
- Topical pediculicides: Permethrin 1 % lotion, pyrethrins combined with piperonyl‑butoxide, or dimethicone‑based silicone preparations.
- Mechanical removal: Fine-toothed nit combs applied to wet, conditioned hair; repeated sessions over 7–10 days eradicate residual nits.
- Environmental control: Washing bedding, clothing, and personal items at ≥ 60 °C or sealing them in plastic bags for two weeks prevents re‑infestation.
Resistance to pyrethroid compounds has been documented in many regions, prompting the use of alternative agents such as ivermectin or spinosad in recalcitrant cases. Monitoring treatment efficacy through follow‑up examinations 7–10 days post‑therapy is recommended to confirm eradication.