Q: My daughter's school keeps sending home notes advising parents to check their child's head for lice. I do so and have had to treat her on each occasion. The lice then seem to go but are back again at the next check. What can I do to stop this happening and which treatment works best?Sincerely, Siobhan
I'M SURE many parents reading this column can empathise with you. Head lice are extremely common, especially in children aged four to 11. They do occur more commonly in girls – this may be due to the fact that they tend to have longer hair which may not be tied back.
A: Lice are small wingless parasites about the size of a sesame seed when fully grown. They vary in colour from pale cream to grey brown. They cannot jump or fly but use their six legs to cling tightly to the hair shaft and to move quite quickly from hair to hair.
They are very contagious among close contacts, so often, in school, children sharing secrets or working closely together can facilitate the lice crawling from head to head. They also travel easily among close family contacts this way. Once lice arrive on a head, they settle close to the scalp. The most common areas to see them are behind the ears and the nape of the neck.
The female louse lays eggs that hatch about seven to 10 days later. The lice feed by sucking small amounts of blood from the host's scalp and become fully grown in about six to 10 days, when more eggs can be laid and the process continues.
The shells left behind after the eggs hatch are referred to as nits and these grow out along the hair shaft. Live lice and eggs can be hard to see because they tend to be very close to the scalp, but if infestation has been there a while, the nits may be more easily seen as they grow out along the hair shaft.
An itching head may be a sign of head lice but it doesn't always occur. The best way to diagnose lice is detection combing. This is best done on wet hair but can be done on dry hair also.
You should purchase a detection comb from the pharmacy. The teeth on these combs should be no more than 0.3mm apart in order to trap the lice. Apply a large amount of conditioner to the hair and comb through with a normal brush or comb.
When the hair is tangle free, start combing through small sections of the hair from scalp to end with the detection comb and check the comb after each segment to look for lice or eggs. Rinse out the conditioner and repeat the combing on the hair again.
The above method needs to be repeated on days five, nine and 13 in order to ensure there are no viable eggs.
There are a number of treatments available.For many years, chemical insecticides were used to kill lice and eggs.
The lice are now resistant to many of these and so Malathion is currently the only one still considered helpful in treating lice, although there has been some resistance to this also.
Malathion (Derbac) is a lotion applied to the hair in the evening, left in overnight (12 hours) and then washed off the next day. The treatment is repeated a week later. Malathion is flammable, so you should not dry the hair when using it or sit exposed to a naked flame or electric heat source. It is a chemical and can cause some irritation of the scalp in some people.
More recently, non-chemical methods have become more popular. These include dimethicone and cyclomethicone treatments (Hedrin and Full Marks solution). These work by suffocating the lice and loosening the eggs so resistance is less likely. These solutions are applied to the hair and left for minutes to hours. Hair is then fine combed and washed.
Other home remedies that have been suggested include applying olive oil or mayonnaise (the full fat variety) and leaving it on overnight and washing off the next day. These are reported to also suffocate the lice but their efficacy is not proven.
Applying a solution or shampoo containing tea tree oil or lavender oil have been reported to reduce the chance of reinfection with lice but again this is not a proven remedy. With any of the above methods, treatment should be repeated at seven days, and for resistant cases again at 13 or 14 days, then fine-combing hair 12 days later to ensure complete eradication is advised.
I would advise trying the non-chemical methods first but Malathion can work if required. In order to prevent reinfection, ensure the whole household is checked and that all requiring treatment receive it. Hopefully all parents advised will also check and treat at the same time, though this doesn't always occur.
Lice can only live for about two days off the human head and cannot pass from or to pets, so although I do advise washing sheets and hairbrushes etc, extreme cleaning methods are not necessary. Do ensure that your daughter's hair is well tied up at all times when in close contact with others.
Finally, itching can persist for a few weeks after the hair has been treated and does not necessarily mean the nits are still present.