|MadSci Network: Medicine|
FACTS AND MYTHS ABOUT HEAD LICE Head lice and personal hygiene Head lice are not a sign of poor hygiene, dirty hair or lack of parental care. Washing hair does not kill head lice, as they can survive under water for several hours. Anyone with hair - long or short, clean or dirty - can get head lice. Head lice and disease Head lice do not carry any disease. However they can make the skin itch and persistent scratching can cause skin infections. Cleaning the house It is not necessary to wash all the household linen, or to vacuum, scrub or spray the house with household insecticide, or to treat the dog or cat. Pillowslips may be soiled with lice debris such as droppings and moulted lice skins, so they should be washed on the first day of treatment. Why is cleaning not recommended? • Head lice do not live in the environment. If they did live in the environment then they would be seen everywhere, like ants, and people would be infested all the time. • Head lice are human parasites and need to feed from the scalp every few hours. They do not survive for more than a few hours away from the body as they quickly dehydrate. • Head lice kept in a sealed jar may live a few hours longer due to the warmth and humidity of the container. (This is not the same as their normal environment and head lice will not reproduce in these different conditions.) • Head lice do not leave the scalp unless they are dead, dying or have been deliberately removed. The blood supply of the scalp is their only food source. • Head lice that fall off the hair at the end of their life cycle are not likely to lay eggs while dying. If they did, the eggs would not survive away from the necessary constant heat and humidity of the scalp. • Head lice that have been deliberately removed from the hair would be unlikely to return since they cannot walk very well. Their curved legs and claws and are designed only for gripping and climbing along the hair shaft. ‘Flying - Jumping - Swimming’ lice Head lice cannot fly, jump or swim. They do not have the hind legs or wings needed to do so. They can run very fast along one hair to get onto another. Head lice can swing or ‘trapeze’ from one hair to another if hairs are very close and this may be mistaken for the insect ‘jumping’. Eggs (‘Nits’) Not every egg found on the hair at any given time will produce head lice. Only those within 1 cm of the scalp will hatch to produce more lice. Most eggs further out along the hair shaft will be already hatched. The rest will simply have died. Vinegar and removal of eggs The cement that glues eggs to the hair is extremely strong and cannot be removed by vinegar. Researchers have found that the structure of the cement is related to the structure of hair and can only be dissolved by strong acid. After the eggs have hatched the cement gradually breaks down and eggs are then much easier to detach. Dye and Bleach There is no evidence that dye or bleach kills or prevents head lice infestations, in the concentrations normally used. Therefore dyed or colored hair is no protection. Using these products to kill lice will cause injury to the scalp, burns to the scalp, loss of hair and other dangers and is definately NOT recommended.
Try the links in the MadSci Library for more information on Medicine.