How dangerous are lice and what do they look like? - briefly
Lice pose minimal health risk, primarily causing itching and potential secondary skin infections if untreated. They are tiny, wing‑less insects about 2–4 mm long, gray‑white in color, with six legs and a laterally flattened body.
How dangerous are lice and what do they look like? - in detail
Lice are small, wing‑less insects that live on the human body, feeding on blood from the scalp, body, or genital region. Adult head lice measure 2–4 mm, are grayish‑white, and have six legs with clawed tarsi that cling to hair shafts. Body lice are slightly larger, 2.5–4 mm, with a broader abdomen and a habit of residing in clothing seams. Pubic lice (crabs) are 1.5–2 mm, have a crab‑like shape, and grasp coarse hair. All species possess a dorsal thorax, a ventral abdomen, and compound eyes that are functional only in bright light.
Health risks fall into three categories:
- Direct blood loss: frequent feeding can cause scalp irritation, itching, and, in severe infestations, anemia, especially in children.
- Secondary bacterial infection: scratching creates micro‑abrasions that allow Staphylococcus aureus or Streptococcus pyogenes to enter, leading to impetigo or cellulitis.
- Disease transmission: body lice are proven vectors for epidemic typhus (Rickettsia prowazekii), trench fever (Bartonella quintana), and louse‑borne relapsing fever (Borrelia recurrentis). Head and pubic lice have not been linked to systemic infections.
Control measures require mechanical removal and chemical treatment. Combing with a fine‑toothed nit comb eliminates nits attached to hair shafts; repeated sessions over two weeks prevent hatching. Insecticidal shampoos or lotions containing permethrin (1 %) or pyrethrin are effective against active lice but do not kill eggs, necessitating follow‑up combing. For body lice, washing clothing at ≥ 60 °C and regular laundering eradicate the habitat. Pubic lice respond to topical permethrin or ivermectin, with careful hygiene to avoid reinfestation.
In summary, lice pose a modest direct threat through blood loss and skin irritation, but body lice can transmit serious bacterial diseases. Their identification relies on size, coloration, and the location of infestation, while eradication combines physical removal with appropriate pediculicidal agents.