YIKES LICE! Lice aren't so nice.

If so, you're not alone. Every year, between 6 and 12 million people worldwide get head lice. Most of those millions are kids. Any kid who goes to school has probably already heard about lice. They can spread easily at schools, so if one kid gets them, the rest of the class might get them, too. What can you do? Let's find out.

Lice aren't dangerous and they don't spread disease, but they are contagious and can just be downright annoying. Their bites may cause a child's scalp to become itchy and inflamed, and persistent scratching may lead to skin irritation and even infection.

Signs of Head Lice

Though very small, lice can be seen by the naked eye. What you, your doctor or your child's school nurse might see by thoroughly examining your child's head:

Lice eggs (called nits). These look like tiny yellow, tan, or brown dots before they hatch. After hatching, the remaining shell looks white or clear. Lice lay nits on hair shafts close to the skin's surface, where the temperature is perfect for keeping warm until they hatch. Nits look sort of like dandruff, only they can't be removed by brushing or shaking them off. Unless the infestation is heavy, it's more common to see nits in a child's hair than it is to see live lice crawling on the scalp. Lice eggs hatch within 1 to 2 weeks after they're laid.

Adult lice and nymphs (baby lice). The adult louse is no bigger than a sesame seed and is grayish-white or tan. Nymphs are smaller and become adult lice about 1 to 2 weeks after they hatch. Most lice feed on blood several times a day, but they can survive up to 2 days off the scalp.

Scratching. With lice bites come itching and scratching. However, the itching may not always start right away — that depends on how sensitive your child's skin is to the lice. It can sometimes take weeks for kids with lice to start scratching. They may complain, though, of things moving around on or tickling their heads.

You may be able to see the lice or nits by parting your child's hair into small sections and checking for lice and nits on the scalp, behind the ears, and around the nape of the neck (it's rare for them to be found on eyelashes or eyebrows). A magnifying glass and bright light may help. But it can be tough to find a nymph or adult louse — often, there aren't many of them and they're able to move fast.

Have your doctor or school nurse check your child's head if your child is constantly scratching his or her head or complains of an itchy scalp that won't go away. They should be able to tell you if your child is infested with lice and needs to be treated.