Common condition in children caused by the parasitic insect Pediculus capitis, which lives on and among the hair of the scalp of humans

Aetiology

• Head lice are small insects that live only on humans, they feed on our blood
  • Eggs are grey or brown and about the size of a pinhead
  • The eggs are glued to the hair, close to the scalp and hatch in 7 to 10 days
  • Nits are the empty egg shells and are white and shiny
  • They are found further along the hair shaft as they grow out.
• Head lice are spread by direct head-to-head contact and therefore tend to be more common in children because they play closely together
• When newly infected, cases have no symptoms but itching and scratching on the scalp occurs 2 to 3 weeks after infection
  • There is no incubation period

Clinical features

• Itching of scalp
• Lice/eggs may be visible

Investigations

• Fine-toothed combing of wet or dry hair

Management

• Treatment is only indicated if living lice are found
• A choice of treatments should be offered - malathion, wet combing, dimeticone, isopropyl myristate and cyclomethicone
• Household contacts of patients with head lice do not need to be treated unless they are also affected