Head lice, also known as pediculosis capitis or nits is a common condition in children caused by Pediculus capitis.
Pathophysiology
Head lice are spread by head-to-head contact as they crawl from one head to the other. They cannot fly or jump. They are approximately 2-3mm long, with a pale grey colour usually. They lay about 10 eggs (called nits) daily which attach firmly to the hair shaft. The eggs are 3-4mm long and can most easily be seen along the hairline and nape of the neck.
They require frequent blood meals and feed by injecting saliva and taking small amounts of blood from the scalp. The saliva leads to an allergic reaction causing itch and irritation.
⚠️ Risk factors
- School children (3-12 years old)
- Female sex
- Living with infested individuals
😷 Presentation
It may be asymptomatic initially.
- Itching and scratching of the scalp. It usually occurs 2-3 weeks after infection. There is no incubation period.
It is difficult to se the lice themselves but the nits can sometimes be seen when examining the scalp.
🔍 Investigations
As mentioned, sometimes the lice or nits can be seen around the hairline and nape of the neck.
- 🥇 Fine-toothed combing of wet or dry hair
🧰 Management
If lice are found, only then is treatment indicated.
- Household contact do not need to be treated unless they are also affected.
- Exclusion from school is not advised in children with head lice.
Treatment options include:
- 🥇 Wet combing - combining wet hair with lice detection comb to remove the lice.
- Physical insecticides:
- 🥇 Dimeticone 4%
- Isopropyl myristate + cyclomethicone
- Chemical insecticides:
- Malathion 0.5% - resistance has been reported.
🥇 First-line treatment from NICE involves wet combing + dimeticone 4%.