Many parents and teachers despair of head lice and nits. Around three million people per year in the UK will catch head lice, known medically as pediculosis capitis.
It is commonplace for lice to circulate among schoolchildren, only to find that once a child has been treated, more lice then appear. Adults can get head lice, but they are far more common in children who come into contact with each other during play. It is not unusal for children to be teased about their lice and it is important to remember that infestation is not a reflection of personal hygiene.
LIFE CYCLE
To combat head lice effectively, it is helpful to understand what they are and their lifecycle. In essence, head lice are insects that grow to around 3mm in length. It's a common misconception that lice can fly or jump; in fact, they spread through direct contact allowing lice to be transferred from one person to another. In addition, given that lice can survive for a few days away from the host's head, they may be transferred by sharing hats and hairbrushes.
Once laid, lice eggs usually remain steadfast in the hair, attached inconspicuously near the hair root, close to the warm scalp. Being close to the scalp also allows the lice to feed easily on blood. It takes just over a week for the eggs to hatch, leaving behind the shell, known as a nit - although people commonly call the living lice 'nits'.
It takes only a week for the lice to reach adulthood. After mating, each female louse is then able to lay her own eggs. On average, infested people have around 20 lice, and over 30 days each louse will lay around 130 eggs. Female lice need only mate once, having the ability to store sperm for later use.
SYMPTOMS
The most common symptom from head lice is itching, which is caused by allergy rather than the lice themselves. As such, people who do not have an allergic response to the lice will not experience any itching. In addition, it may take months before the lice trigger an allergic response. Louse faeces may also cause a rash on the scalp and at the back of the neck.
As many children will remain symptom free, many schools and parents choose to regularly screen children for lice. Nevertheless, detection of active infestation this way is not always straightforward, partly because nits may remain after the lice and eggs have been cleared.
TREATMENT
The use of combs to detect an infestation is advocated by most GPs, and pharmacists can recommend a good quality comb that will detect both nits and lice. Wet hair with lots of conditioner should be detangled with a standard comb before using the head lice comb, ensuring the comb edges are flush with the scalp. After each sweep, the comb should be checked for lice.
Treatment of lice isn't always successful, partly due to the reinfestation rate, and lice may become resistant to standard lice lotions. Newer treatments such as silicone and oil-based products do not lead to resistance. Wet combing may be used to treat the infestation.
To be successful, wet combing should be repeated on five, nine and 13 days after the initial treatment.
Medicated treatments offer an alternative to combing and some people may prefer them. Shampoos tend not to be effective. Lotions are recommended as long as lice have actually been seen. Different preparations have varying instructions, but they usually require that the treatment is repeated after a week, to cater for the lifecycle of the lice. There may be medical reasons why some treatments should not be used, so seek professional advice first.
Children affected by lice need not be kept off school, but the school should be informed. Both the child's family and classmates should be screened and treated only if they are found to have lice.
Dr Raj Thakkar BSc(Hons) MBBS MRCGP MRCP(UK) is a full-time GP in Buckinghamshire.