What are the characteristic features of head lice infestation?

Head lice infestation is transmitted by head-to-head contact; transfer by other means is unlikely.

Live and dead lice (about 3mm long and greyish-white or brown in colour) and yellowish cast exoskeleton shells can be seen by wet combing – combing the hair with a fine-tooth comb over a sheet of white paper after shampooing and towelling dry. Lice faecal material (black specks) may be found on pillows and collars.

Itching, an allergic response to lice saliva injected into the scalp to liquefy blood, may occur after several weeks of infestation and persist for several weeks after successful treatment.
Creamy-coloured empty egg cases – ‘nits’ – remain firmly attached to hair shafts as they grow outwards. They are a sign of previous, not necessarily current, infection.