You may have lice and not even know it. The problem is that sometimes they make people's heads itch, and sometimes they don't. If they don't, you simply wouldn't know that your head was infested with parasites. There is often a tickling sensation associated with lice, however, but it's not the kind that makes you want to laugh. It's more likely to be an uncomfortable and irritating nuisance. Whether lice make you itch or tickle, the most common reaction is scratching, and that's where physical symptoms start appearing.
The itching associated with lice is actually an allergic reaction to their saliva [source: Mayo Clinic]. This may cause red bumps on your scalp, but you can also end up with bumps and irritated sores by scratching too much. In some cases, this may even lead to a bacterial infection requiring treatment with antibiotics [source: Gavin]. This is the extreme, however. Most people who become infested with lice experience minor irritation, and the only way to identify the problem is with careful observation.
Lice are small, but they're not so small that you can't see them. The easy way to determine whether or not you or someone else has lice is to do a quick inspection of the scalp. There are basically three things to look for: nits, nymphs and lice. Nymphs, which are young lice, and lice aren't easy to see. They're about the size of a sesame seed and they move quickly. If you catch a glimpse of one, you're lucky. What you're more likely to find are nits, or lice eggs. These tiny eggs can be yellow, tan or brown, and you'll find them attached to hair shafts near the scalp. They hatch one to two weeks after they're laid, so if you find any, treat the scalp and hair immediately [source: Gavin].
Lice aren't necessarily easy to prevent, but there are a few things you can do to lower your chances of becoming infested. Keep reading to find out what they are.