What do lice do to a person? - briefly
Lice cling to scalp or body hair and ingest human blood, causing localized itching and irritation. Their bites may provoke scratching, skin inflammation, and, occasionally, secondary bacterial infection.
What do lice do to a person? - in detail
Lice are obligate ectoparasites that feed on human blood. Female head lice insert their mouthparts into the scalp, draw several milliliters of blood per day, and lay eggs (nits) on hair shafts. The feeding process injects saliva containing anticoagulants, which provokes a localized hypersensitivity reaction. This reaction manifests as intense itching, redness, and small papules around the bite sites.
Repeated bites can lead to:
- Secondary bacterial infection from scratching
- Crust formation and scaling of the scalp
- Hair breakage due to mechanical irritation
Body lice (Pediculus humanus corporis) reside in clothing seams and move to the skin to feed. Their bites produce similar pruritic lesions, often on the torso, hips, and thighs. In addition to skin irritation, body lice are vectors for serious pathogens, including Rickettsia prowazekii (epidemic typhus), Borrelia recurrentis (relapsing fever), and Bartonella quintana (trench fever). Transmission occurs when lice are crushed or when feces containing the organisms contaminate skin abrasions.
Pubic lice (Pthirus pubis) attach to coarse hair in the genital region and other body areas. Their bites cause erythematous papules and intense itching. Though they rarely transmit disease, heavy infestations may cause inflammation and secondary infection of the affected region.
The presence of any lice species can result in:
- Psychological distress and social stigma
- Sleep disruption due to nocturnal feeding
- Potential for widespread outbreak in communal settings such as schools, shelters, and prisons
Effective management requires:
- Mechanical removal of live insects and nits using fine-toothed combs or thorough inspection of clothing and bedding.
- Application of approved topical pediculicides (e.g., permethrin 1 % or dimethicone) following label instructions.
- Laundering of clothing, bedding, and personal items in hot water (≥ 130 °F/54 °C) and drying on high heat to eliminate surviving stages.
- Re‑inspection after 7–10 days to eradicate any newly hatched lice.
Prompt treatment reduces skin irritation, prevents secondary infections, and curtails transmission of disease‑bearing lice species.