General characteristics
Headlice (latin name Pediculus capitis) are very small wingless parasitic insects that are a sucking class of louse, in the Phthirapta order of insects, that suck tiny amounts of blood from the scalp of humans. Unlike their close relatives the body louse (Pediculus corporis), headlice do not spread disease but are nevertheless highly contagious through close body contact.
There life cycle consists of 3 phases, the egg stage, nymph stage and adult stage. On arriving on a new head the adult will begin laying eggs, or 'nits' as they are commonly known, which she attaches firmly to the hair shaft near the root of the hair. She only needs to mate once in her lifetime. She will lay around 6 new eggs every day of her life which will hatch after a week or so. The original adult continues to lay new eggs daily but will die at about a month old, by which time she could have laid up to 180 eggs. The newly hatched nymphs will shed their skin 3 times on their way to adulthood and be ready to reproduce themselves after about 2 weeks from hatching. The cycle then continues on and on until all eggs and lice are removed from the head.
The symptoms of headlice infestation include itching of the scalp and an itching on the skin of the neck and around the ears which is usually caused by irritation from louse droppings. If you thoroughly ruffle the hair over a dry bath then add a small amount of water, you may notice tiny flecks of blood. These are the droppings.
Not all people have itching but usually one can feel something moving around as numbers increase on the scalp.
Resolution can only really be achieved by thorough examination of the hair and scalp regularly (probably daily), removing all eggs and lice once detected. Eggs are tricky to remove even with a good comb and even harder to spot, looking like a tiny blob on the hair shaft. They appear more translucent when the nymph has hatched out and the cases are empty. Adult lice seem subdued after washing the hair and wet conditioned hair is easiest to work on.
Commercial preparations based on toxic insecticides will not kill all (if any) of the eggs so do not rely on them. Some lice build up complete resistance to even very strong preparations in a very short time, so using them makes the problem worse in the long run. I personally do not want insecticides on my children's heads anyway.
Comments