A: We encourage our children to be friendly, play, and share with other children. And while children share many nice things, they also share contagious conditions such as head lice—Pediculus humanus capitustiny— insects that live on blood from the human scalp. When you first hear that children at school or child care have head lice, most parents react with shock and disbelief. When your own child starts scratching his head and you see the lice, you may feel upset and embarrassed. And if your child gets head lice again, you'll likely feel exasperated.

But we have to face the facts—dealing with head lice is a common part of childhood and parenthood. Head lice have been around for thousands of years and infest 10-12 million children in the U.S. each year. So take a deep breath and prepare yourself to deal with head lice:

1. Don't feel bad about it. Head lice don't spread because of poor hygiene, but rather because of close physical contact among children and sharing hats, hairbrushes, pillows, etc. Try to deal with it calmly so your child doesn't feel bad either.

2. Check everyone in your household for head lice.

• Look for scratching around the scalp and neck, which are a common sign of head lice infestation.
• Learn how to spot the two life stages of head lice: the louse and the nits. Visit the National Pediculosis Association's website, www.headlice.org, to view photos of what to look for:
• • The louse is a six-legged insect that is gray or brownish and a little larger than a sesame seed. Lice crawl quickly, hide in the hair, and can be difficult to see and catch.
  • The nits are the tiny eggs laid by the lice. They are gray or whitish, teardrop-shaped, and the size of sesame seeds. The lice lay the nits with the pointed end glued to the hair and the rounded end sticking out at a slight angle, within a quarter inch from the scalp. Don't confuse nits with dandruff flakes from the scalp which may have more jagged edges, surround a hair, and can generally be flicked off.
• Search carefully through each child's hair for lice and nits. You might also see little bloody bites or scratches on the scalp. Seat each child under very good light for the check. Magnifying glasses can be helpful. Start looking where the head lice most commonly infest—the warmer parts behind the ears and around the hairline at the back of the neck. Separate the hair into one-inch sections and proceed around the whole head to get a good look at all of the hair and scalp. Make sure you have another adult check through your hair, as well. Don't worry about checking your pet—they don't catch head lice.

3. Treat children and adults who have head lice with the special medicated shampoo for head lice. The treatment is available in pharmacies over-the-counter. Look for a treatment that is both a "pediculicide" (kills lice) and "ovicide" (kills nits). Remember, this treatment is a pesticide and must be used with caution. Follow the instructions carefully when applying the shampoo, and avoid getting it in the eyes or in cuts. The instructions may include repeating the treatment after 7-10 days. For infants under 1 year old, pregnant or nursing women, or someone with allergies, ask your doctor about a safe treatment. Some people use petroleum jelly, mayonnaise, and olive oil, but their effectiveness is unknown. Never use other pesticides or kerosen—these could be fatal.

4. After shampooing, go through the hair thoroughly to remove all the lice and nits. This "nit-picking" is crucial since no head lice shampoo is 100% effective, and the remaining lice and nits could continue to reproduce. Again, seat your child under good light. Divide the hair into inch-wide sections and comb through all the hair from the base to the tips with a fine-toothed comb. After combing, go through the hair sections by hand and pick out the remaining lice and nits with your fingernails, or use small scissors to cut out the hairs with nits. It can take up to 20 minutes, depending on how thick and long your child's hair is. Repeat the hair checks and removal of lice and nits every day for 1-2 weeks, to be sure they're all gone.

5. Launder all clothing, bed linens, towels, and stuffed animals that have been in contact with the infested person in the past few days. Wash them in hot water and dry in a hot dryer. Non-washable items can be run through a hot dryer cycle, dry-cleaned, or sealed in a plastic bag for 10 days. Vacuum carpets, upholstered furniture, and car seats. Wash combs and brushes in the lice shampoo or soak in hot water for 10 minutes. Do not use insecticidal sprays.

6. Notify your child's school, child care, and the parents of your child's playmates so they can check for head lice. Although it may be embarrassing, it's crucial that everyone be informed and do their part to get rid of head lice. A calm attitude, good cooperation, and a sense of humor can go a long way to effectively deal with head lice.