What is a pubic louse and where does it come from? - briefly
Pubic lice (Pthirus pubis) are tiny, crab‑shaped ectoparasites that live on coarse body hair, feeding on blood. They are transmitted primarily through close sexual contact or sharing contaminated clothing, bedding, or towels.
What is a pubic louse and where does it come from? - in detail
Pubic lice, scientifically known as Pthirus pubis, are small, crab‑shaped ectoparasites that inhabit coarse body hair, primarily in the genital region but also in the axillae, beard, chest, and eyebrows. Adult specimens measure 1–2 mm, with a flattened body and robust posterior legs adapted for grasping hair shafts. The insect’s mouthparts pierce the epidermis to ingest blood, causing irritation and secondary infection.
The life cycle comprises three stages: egg (nits), nymph, and adult. Females embed eggs at the base of hair follicles; each egg hatches in 6–10 days. Nymphs undergo three molts over approximately two weeks before reaching maturity. Fully developed lice survive up to 30 days on a host but die within 24–48 hours without blood.
Transmission occurs through direct physical contact that brings the parasite’s claws into contact with hair. Primary vectors include:
- Sexual intercourse, the most common route.
- Close, non‑sexual skin‑to‑skin contact (e.g., sharing bedding or towels).
- Rarely, fomites such as contaminated clothing or furniture.
Geographic distribution is worldwide; prevalence is higher in populations with dense sexual networks and limited access to hygiene resources. Infestations affect both sexes and all age groups, though rates are lower among children.
Clinical manifestations appear within a few days after infestation:
- Intense pruritus localized to infested hair zones.
- Small bluish or reddish macules representing bite sites.
- Visible adult lice or translucent nits attached to hair shafts, often near the scalp base.
- Secondary bacterial infection from scratching.
Diagnosis relies on visual inspection using a magnifying lens. Nits are distinguished by their firm attachment to the hair shaft and oval shape; they are not easily removed by combing. Microscopic examination can confirm species identification.
Effective management includes:
- Topical pediculicides (e.g., 1 % permethrin cream, 0.5 % malathion lotion) applied to affected areas and left for the recommended duration.
- Oral ivermectin (200 µg/kg) for cases resistant to topical agents or when extensive body hair involvement exists.
- Mechanical removal of nits with fine-toothed combs after treatment to reduce reinfestation.
- Washing of clothing, bedding, and towels at ≥60 °C or sealing them in plastic bags for two weeks to eliminate surviving lice.
Prevention emphasizes avoiding direct contact with infested individuals, refraining from sharing personal items that contact hair, and promptly treating partners when an infestation is identified. Regular inspection of body hair in high‑risk groups facilitates early detection and limits spread.