How are lice harmful to people? - briefly
Lice bite the scalp or body to ingest blood, leading to intense itching, skin irritation, and possible secondary bacterial infections from scratching. In some cases they can transmit pathogens such as Bartonella quintana, which causes trench fever.
How are lice harmful to people? - in detail
Lice infestations cause a range of physiological and psychological problems.
Direct skin irritation results from the insect’s bite. Saliva injected while feeding triggers itching, redness, and localized swelling. Repeated scratching can break the epidermis, creating entry points for bacterial pathogens such as Staphylococcus aureus and Streptococcus pyogenes. Secondary infections may develop into impetigo, cellulitis, or erysipelas, requiring medical treatment.
Allergic reactions occur in some individuals. The immune system may produce hypersensitivity to louse saliva, leading to urticaria or eczema‑like eruptions that persist even after the parasites are removed.
Transmission of disease, although rare for head lice, is documented for body lice (Pediculus humanus corporis). These vectors can carry Rickettsia prowazekii (epidemic typhus), Borrelia recurrentis (relapsing fever), and Bartonella quintana (trench fever). Outbreaks typically arise in crowded, unhygienic settings where body lice thrive.
Psychological impact includes embarrassment, social stigma, and anxiety. Persistent infestation can impair concentration, reduce academic or work performance, and contribute to low self‑esteem.
Economic burden stems from treatment costs, medical visits, and lost productivity. Over‑the‑counter and prescription remedies, as well as professional extermination services, add financial strain, especially in low‑income communities.
Key consequences can be summarized:
- Cutaneous inflammation and itch
- Skin breakdown leading to bacterial infection
- Allergic hypersensitivity reactions
- Vector‑borne diseases (typhus, relapsing fever, trench fever)
- Mental health effects such as stress and stigma
- Financial losses from treatment and absenteeism
Understanding these effects guides effective prevention, prompt diagnosis, and appropriate therapy, reducing the overall harm caused by lice infestations.