There is a short answer and a long answer to this question. The short answer is that if you or your child have lice, you got them from another person through head-to-head contact. Although there is a very slight possibility that you could get lice from an inanimate object, such as a brush or a pillow case, almost all cases of head lice occur through direct head to head contact with someone who is infested.
The longer answer goes back over , years. Scientists believe head lice began to evolve on a different path than body lice about the time humans started to wear more clothing. Body lice evolved to attach to clothing fibers which are typically thicker and stronger than a human hair. Head lice stuck with the scalp. Researchers have used this information to speculate that humans may have used clothing much earlier than previously believed.
Clade B head lice are thought to have originated in North America, and then to have migrated to farther reaches of the world, including Australia and Europe. The DNA from the mitochondria of head lice cells collected from lice around the world have been used to trace back the ancestry of lice to a common lineage about 2 million years ago.
They now believe that Clade C then split off from the group. Much later, between , and 1 million years ago, Clade B split from Clade A. Scientists believe that lice, due to their relationship with humans, can provide important information about human evolution. Nymph: A nymph is an immature louse that hatches from the nit. A nymph looks like an adult head louse, but is smaller.
To live, a nymph must feed on blood. Nymphs mature into adults about 9—12 days after hatching from the nit. Adult: The fully grown and developed adult louse is about the size of a sesame seed, has six legs, and is tan to grayish-white in color. Adult head lice may look darker in persons with dark hair than in persons with light hair.
To survive, adult head lice must feed on blood. Adult female head lice are usually larger than males and can lay about six eggs each day. Head lice and head lice nits are found almost exclusively on the scalp, particularly around and behind the ears and near the neckline at the back of the head. Head lice or head lice nits sometimes are found on the eyelashes or eyebrows but this is uncommon. Head lice hold tightly to hair with hook-like claws at the end of each of their six legs.
Head lice nits are cemented firmly to the hair shaft and can be difficult to remove even after the nymphs hatch and empty casings remain. Head-to-head contact with an already infested person is the most common way to get head lice. Head-to-head contact is common during play at school, at home, and elsewhere sports activities, playground, slumber parties, camp.
Although uncommon, head lice can be spread by sharing clothing or belongings. This happens when lice crawl, or nits attached to shed hair hatch, and get on the shared clothing or belongings. Examples include:. The diagnosis of a head lice infestation is best made by finding a live nymph or adult louse on the scalp or hair of a person.
Because nymphs and adult lice are very small, move quickly, and avoid light, they can be difficult to find. Use of a magnifying lens and a fine-toothed comb may be helpful to find live lice.
Nits are often confused with other things found in the hair such as dandruff, hair spray droplets, and dirt particles.
If you are not sure if a person has head lice, the diagnosis should be made by their health care provider, local health department, or other person trained to identify live head lice. More on: Treatment. Most health departments do not require reporting of head lice infestation. However, it may be beneficial for the sake of others to share information with school nurses, parents of classmates, and others about contact with head lice. Head lice : Just thinking about it is enough to make you itch.
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. These misconceptions only help feed into the anxiety of parents whose children have lice or who have been exposed to lice.
Lice are tiny insects that live in hair, bite, and can multiply quickly, laying up to 10 eggs a day. Anyone can get lice, regardless of age, social status, race or gender.
Lice are parasites that live off human blood. They must move to a new head within around 24 hours , or they will die. Elementary school- or preschool-aged girls are the group most likely to get lice. Lice are also common in boys of the same ages. Some people believe that girls are more vulnerable to lice than boys because they tend to have longer hair and more head-to-head contact. Each year, around 6—12 million cases of lice occur in children aged 3—11 in the United States.
These items can include:. Poor communication can also be a risk factor. If a person has lice, it is essential to inform everyone in close contact.
If a child has lice, a parent or caregiver should notify the school or daycare. Other signs and symptoms can include:. These symptoms can point to a range of issues, so it is important to confirm the presence of lice before starting treatment. The best place to look for live lice is on the scalp behind the ears.
If the lice do not seem to be living, a person may not have an active infestation. Many effective medications can eradicate lice. A doctor or pharmacist can help a person to choose the best method of treatment.
Standard treatments include over-the-counter OTC liquids, shampoos, and lotions called pediculicides. These products contain medication that kills the lice. The packaging will include instructions about how long to leave the product on the hair, and it is important to follow these guidelines.
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