What is on the head: lice or fleas? - briefly
Head lice (Pediculus humanus capitis) infest human scalps; fleas do not live on the head and are associated with animals.
What is on the head: lice or fleas? - in detail
Head lice (Pediculus humanus capitis) are obligate human ectoparasites that live on the scalp, lay eggs (nits) on hair shafts, and feed on blood. Fleas, such as Ctenocephalides felis or C. canis, prefer mammalian hosts like cats and dogs; they may bite humans but do not establish a population on hair.
Lice are 2–4 mm long, flattened, with six legs that cling to hair. Their bodies are gray‑brown and lack jumping ability. Fleas are 1.5–4 mm, laterally compressed, equipped with powerful hind legs for jumping, and usually appear dark‑brown to reddish.
Lice cause persistent itching due to scalp irritation and the presence of nits, which are ovoid, cemented to the hair at a 45° angle. Flea bites produce isolated, red papules with a central punctum, often on exposed skin such as ankles or arms, not on the head.
Diagnosis relies on direct visual examination. A fine‑tooth comb over damp hair reveals live lice and attached nits. Fleas are identified by their jumping behavior and characteristic flea dirt (black specks of digested blood) on clothing or bedding.
Treatment for head lice includes topical pediculicides (e.g., 1 % permethrin, 0.5 % ivermectin) applied to the scalp, followed by thorough combing to remove nits. Persistent cases may require oral ivermectin. Flea infestations are addressed by treating the animal host with veterinary‑approved products, vacuuming environments, and applying insecticide sprays or foggers to carpets and upholstery.
Prevention of lice spread involves avoiding shared combs, hats, or bedding, and performing regular head inspections, especially in communal settings. Flea prevention requires routine pet grooming, regular use of flea collars or topical treatments, and maintaining clean indoor areas.
In summary, the scalp can host only lice; fleas may bite humans but do not inhabit head hair. Accurate identification, appropriate treatment, and targeted preventive measures differentiate the two conditions.