How can lice be recognized? - briefly
Lice are detected by spotting live, wingless insects about 2–4 mm long attached to hair shafts, often accompanied by intense itching from their bites. Their eggs, called nits, appear as tiny, oval, amber‑colored shells firmly glued to the hair within a few millimetres of the scalp.
How can lice be recognized? - in detail
Lice detection relies on direct observation of the insects and their eggs, supported by characteristic symptoms on the host. Adults are approximately 2–4 mm long, flattened, and have six legs. Their bodies are grayish‑white to brown, with a crab‑like appearance. Movement is rapid; they cling to hair shafts near the scalp, especially behind the ears and at the nape of the neck.
Eggs, commonly called nits, measure about 0.8 mm, are oval, and attach firmly to hair fibers at a 30‑degree angle. A viable nit is firmly glued and cannot be brushed off easily. Empty shells, or nits that have hatched, appear translucent and may be easier to remove.
Key visual cues include:
- Live insects crawling on the scalp or hair.
- Clusters of firmly attached nits close to the scalp.
- Small, red bite marks or puncture spots on the skin.
- Localized itching, often intensifying after a period of latency.
Effective inspection methods:
- Separate a small section of hair (about 5 cm) and examine it against a white background.
- Use a fine‑toothed comb (nit comb) to pull hair through, collecting insects and nits on the comb teeth.
- Employ a magnifying lens (10×) to differentiate live nits from empty shells.
- Conduct the examination in a well‑lit area; natural daylight or a bright lamp reduces misidentification.
Additional diagnostic steps:
- Perform a “wet comb” technique: wet the hair, apply conditioner, then comb repeatedly to loosen lice.
- Collect suspected insects in a clear container for laboratory confirmation if needed.
- Compare findings with known morphological features; head lice (Pediculus humanus capitis) differ from body lice (Pediculus humanus corporis) in habitat and size.
Recognition concludes when live lice are observed, or when at least three firmly attached nits are found within a 1‑cm radius of the scalp. Absence of these criteria, despite itching, suggests alternative causes and warrants further medical evaluation.