Head lice (also known as pediculosis capitis or 'nits') is a common condition in children caused by the parasitic insect Pediculus capitis, which lives on and among the hair of the scalp of humans.

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. They cannot jump, fly or swim! 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.

Diagnosis

• 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

School exclusion is not advised for children with head lice