Sometimes you will get an itchy feeling at the back of your head.
Maybe it's that new shampoo you're using, or maybe it's the heat.
It would be interesting, though a bit gross, to point to one factor as to why your head has been itching: maybe it's because of a head louse, or 20 of them.
According to the Annual Review of Entomology by Ian Burgess, over 12 million people in the United States alone suffer from louse infestation, and without head lice treatment such as lice shampoo, they'll end up scratching their heads red.
Before anything though, what is a head louse anyway? A head louse, or Pediculus humanus capitis, is a wingless insect of the order Phthiraptera and is an obligate ectoparasite.
Meaning, it is a parasitic organism that feeds on the blood of its host.
Without that blood, it will die.
So it makes one heck of an effort to stay on its host indefinitely.
Attached to its thorax are six short but powerful legs containing claws: these claws are used to cling to the hair of their host, which in this case is a person's head.
When a head louse attaches itself to the hair of a person, it waits there until it is time to feed on the person's blood.
This happens four to five times a day.
What a head louse does is it bites through the skin of the person and injects its saliva, which contains substances that prevent blood clotting, allowing it to feed continuously.
Any part of a person's scalp may be colonized by head lice; however, a head louse will prefer the area of the nape of the neck and the spot behind a person's ears.
They also shy away from light, and will move toward dark-colored places within close proximity.
People usually get a louse infestation, or what's referred to as Pediculosis capitis, through close contact between people.
When a head louse feeds, this causes you to feel that itchy sensation you're feeling on your head.
This can cause welts, swelling, and can even lead to secondary infection.
To prevent this, one can perform head lice treatment to get rid of those pesky head lice.
There are many ways to cure Pediculosis capititis.
The earliest method would be manual nitpicking, which is basically going through a person's hair and removing each louse by hand.
This is a tedious process which can take a long time and a lot of effort.
A number of people, who don't have the time or the patience for this, simply shave their heads to get rid of these parasites.
Finally, one method that seems to be gaining popularity is the lice shampoo treatment.
These shampoos are especially formulated with certain protease enzymes.
These enzymes are similar to the ones found in the insects themselves, and work by causing a louse to molt or hatch from an egg prematurely, destroying its exoskeleton and killing it.
Since the enzyme can be found in the louse itself, there is no danger of it developing a resistance.
This treatment, by far, is proving to be very effective and is gaining quite the following.