Infestation with Head Lice is a global issue; people of any age can be affected, however head lice tend to be more common in children. Although the exact rates of infestation in the UK are unknown, studies have shown that around 8% of children in primary schools have live lice.
These days people tend to find the idea of head lice infestation disgusting, however it is probably worth noting that a head louse infestation only really causes itching an no other physical problems and that Lice are not known to carry or transfer any diseases.
Treatment of Head Lice requires knowledge of 2 key things:
- The methods that are available
- The life-cycle of the head louse
In recent years new products have become available that promise to make treatment easier and more convenient.
Head Lice are parasitic insects that live on the human scalp and feed on blood four to five times a day. They hang on to hairs close to the head, normally behind the ears or in the nape of the neck and are only rarely found in other hairy areas. They have strong claws and cannot be removed from the hair by normal combing or brushing.
Head lice are spread through head-to-head contact because they cannot fly, jump or swim. This means that they are very unlikely to be spread through sharing combs, brushes, towels, clothing or bedding as they cannot survive for more that 12 hours away from their host. If a louse drops out of the hair than it is normally injured or too weak to crawl back to its host and will die.
Mature lice are about 3mm long and be beige, brown or blackish often camouflaging to the surrounding hair. The fertilised female can lay 5 to 10 eggs a day. The oval, yellowish-white eggs are golued singly to the hair shaft.
After 7 days the egg hatches leaving an empty egg case (or nit) stuck in the hair. Young lice are known as nymphs; they are white and smaller than adults. Over the next 10 days the nymph will moult three times and grow into a mature louse. Lice feed by piercing the skin and sucking blood from the scalp.
All the recommended treatments kill the adult lice but are less effective on the nymphs and eggs. This is why it is recommended to do a second treatment after 7 days to kill all of the freshly hatched nymphs. It is important to check that treatment has been effective 2-3 days afterwards. A Lice detection comb should be used again 8-10 days after treatment.
The main agents that are used for the treatment of head lice are physically acting compounds (dimeticone-based) and insecticides, including pyrethroids (permethrin), malathion and carbaryl. All of these except carbaryl can be supplied without a prescription.
The way that treatments like Hedrin work are not fully understood but it is believed that they work by coating the lice and disrupting their water balance meachanisms, stopping them from excreting waste and causing them to die. This means that these products are highly effective even on lice that may have become resistant to insecticides. You should always follow the instructions on any packaging fully.
Insecticide treatments like Derbac M, which use Malathion, or Lyclear are normally applied to dry hair so that the scalp and roots are saturated. It is then left to dry naturally and washed off after 12 hours. Shampoos and foam products are not normally as effective due to the short amount of contact time and the low strength of many that are available.
Pregnant women and people who suffer from asthma or eczema are normally advised to use Dimeticone based products (Hedrin).