What are head lice?

Head lice are tiny insects that live on the scalp. They do not live on pets or other animals. A louse (the singular form of lice) has six legs, each with a curved claw that can tightly hold onto hair. Head lice crawl easily between hairs, but they cannot fly or jump.

Head lice feed on human blood only. A louse does not dig or burrow into the skin–it uses its needle-like mouthparts to suck blood through the skin.

Photograph by Gilles San Martin.

How do you get lice?

Head lice are almost always caught directly from another person, usually children. This typically happens when people are in direct head-to-head contact, such as when they share a bed or play together in close proximity. Louse eggs cannot move and are not transmissible. Head lice are rarely transmitted via a shared comb, hat or helmet. Head lice that fall off a person quickly starve and usually die within 15 hours (and most become incapable of feeding between 3-18 hours off a host). So lice that fall on a desk, floor or coat at school will not be alive the next day. Clothing, stuffed animals, theater seats and other items are not threats to spreading head lice. Bathing every day will not prevent or wash away head lice. Cleaning the home or bagging toys and clothing won’t help you prevent or get rid of head lice.

What is the head lice life cycle?

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.Head lice only live for about three weeks. An adult female louse will lay about six eggs (nits) each day. She attaches each egg with a cement-like material that does not wash out. If the louse mated, her eggs may develop during the next 9 days. The eggs do not grow, move or cause any health problems. Once developed, the young louse (called a nymph) breaks out of the egg, crawls on the hair and leaves behind the now empty eggshell. The empty egg will never produce another louse, but it will remain glued to the hair until it is broken or cut off.The nymph will grow in size and shed its skin every few days until it has matured to become an adult. Only the adult female can lay eggs.

What are the symptoms of lice?

Scratching. With lice bites come itching and scratching. This is actually due to a reaction to the saliva of lice. However, the itching may not always start right away — that depends on how sensitive a 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.
Small red bumps or sores from scratching. For some children, the irritation is mild; for others, a more bothersome rash may develop. Excessive scratching can lead to a bacterial infection (this can cause swollen lymph glands and red, tender skin that might have crusting and oozing). If your doctor thinks this is the case, he or she may treat the infection with an oral antibiotic.

How do you identify lice?

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 with a fine-tooth comb 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 move fast. Be sure to check with your child’s school nurse or childcare center director to see if other children have recently been treated for lice. If you discover that your child does have lice or nits, contact the staff at the school and childcare center to let them know. Find out what their return policy is. Many schools have a “No Nit” policy and will not let children return to school if they have nits in their hair.

Are Lice Contagious?

Lice are highly contagious and can spread quickly from person to person, especially in group settings (like schools, childcare centers, slumber parties, sports activities, and camps).

Though they can’t fly or jump, these tiny parasites have specially adapted claws that let them crawl and cling firmly to hair. They spread mainly through head-to-head contact, but sharing clothing, bed linens, combs, brushes, and hats also can pass them along. Kids are most prone to catching lice because they tend to have close physical contact with each other and share personal items.

How do you prevent reinfestation?

Here are some simple ways to get rid of the lice and their eggs, and help prevent a lice reinfestation:

· Wash all bed linens and clothing that’s been recently worn by anyone in your home who’s infested in very hot water (130° F [54.4° C]), then put them in the hot cycle of the dryer for at least 20 minutes.

· Dry-clean anything that can’t be washed (like stuffed animals). Or put them in airtight bags for at least 2 days.

· Vacuum carpets and any upholstered furniture (in your home or car), then throw away the vacuum cleaner bag.

· Place all hair-care items like combs, barrettes, hair ties or bands, headbands, and brushes in a zip-lock bag and put in the freezer for 8 hours. You also can wash them in hot water or just throw them away.

Because lice are easily passed from person to person in the same house, bedmates and infested family members also will need treatment to prevent the lice from coming back.