What are head lice?
Head lice are small, crab-like parasites that can live on the scalp. They are fairly common in schools, very contagious, and can sometimes cause real outbreaks. Having head lice does not indicate poor hygiene, as is sometimes assumed. The lice climb from one hair to another with small claws — they do not jump or fly. This climbing is fairly quick, so with close contact between two people the lice can “step over”. Lice can also be transmitted from one person to another via clothing (coats, hats).
Lice live on blood that they suck from the scalp, “drinking” on average 3 to 6 times a day; if a louse cannot reach the scalp regularly, it starves and dies. The bite sites can itch considerably, so itch is often the first sign of a lice infestation. The lice glue their eggs (called nits) to the hair shaft. After 8 days the young lice hatch and become sexually mature after about 10 days; a louse can produce about 6 nits a day. The number of lice per infected head is usually not very large (about 20), but many nits can be present.
What are the symptoms?
The main complaint is itch, caused by the lice’s saliva introduced into the skin during blood-sucking. When the itch leads to scratching, small wounds can form that can in turn become infected by bacteria, which can lead to painful inflammation.
How is it treated?
There are three approaches: combing, smothering, and chemical treatment. Systematic wet combing is regarded as the method of first choice.
Combing. The hair must be combed through systematically several times a week with a special lice comb. Both lice and nits are found mainly close to the scalp. The hair should be damp for an optimal result and it should be done in good light. Combing over white paper lets you catch and check the “harvest”. Combing is very labour-intensive, and it is not always easy to keep children sitting still (a screen may help).
Smothering the lice. Besides combing, lotions or gels containing dimeticone can smother the lice: the dimeticone lays a thin layer over the louse so it can no longer regulate its water balance. According to most instructions the product must be left on for 8 hours before being washed out. Dimeticone is not a pesticide.
Chemical treatment. This consists of a lotion or shampoo that damages the louse’s nervous system so it dies; nits are also killed this way. Usually a single treatment is enough. Care must be taken to treat the scalp behind the ears and in the neck as well. Several lice-killing lotions exist (such as malathion, bioallethrin/piperonyl butoxide and permethrin) that barely differ in effectiveness; read the instructions before use. Unfortunately, some lice strains have become resistant to one or more of these agents, meaning the treatment has insufficient effect and lice or nits survive. Note: some agents are unsuitable for pregnant women and very young children — never treat pregnant or breastfeeding women or small children without consulting your doctor.
Extra measures
- Treat everyone infected with lice at the same time.
- Check your child’s hair regularly after treatment.
- Nits die from treatment but stay glued to the hair, so finding nits does not necessarily mean a new infection.
- Wash all bedding and clothing of infected people at at least 60 °C.
- At school or sports club, keep coats/scarves/hats in sealed plastic bags rather than on the coat rack, to prevent transmission via clothing.
- Keep nails short to prevent injury from scratching.
If the lice keep coming back
There are several reasons lice do not disappear: the treatment was not carried out precisely enough (was the hair combed often enough?); there is re-infection by others (at school or a sports club — contact the teachers); or the louse is resistant to the insecticide used, which is increasingly common — in these cases consistent combing is really the only solution.
When to see a doctor
See a doctor if the scalp becomes infected from scratching, if treatments repeatedly fail, or before treating a pregnant woman, a breastfeeding woman or a very young child.