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What are head lice?
- Head lice are tiny (about the size of a sesame seed), wingless parasitic insects that must live on a person (usually on the scalp) to survive.
- Human head lice (Pediculus humanus capitus) have been associated with humans for thousands of years.
- They survive by piercing the skin to feed on blood and are almost exclusively associated with hair on the neck and scalp.
- The majority of head lice infestations occur by direct head-to-head contact with an infested person.
Who is at risk?
Anyone can get head lice, but some people are at greater risk than others.
Those people include:
- Children between the ages of 3 and 11 years
- Girls are more likely to get head lice than boys, possibly because of their play styles and sharing of personal items.1
- People with long or short hair can contract head lice. Although all races can get head lice, studies show that children of African-American descent are less likely to become infested. 1
1. Centers for Disease Control and Prevention, Head Lice Epidemiology: http://www.cdc.gov/parasites/lice/head/epi.html
Signs and Symptoms
What are the symptoms of head lice?
Parents, teachers, and other care givers should be aware of the signs and symptoms of a head lice infestation because young children may not be able to express their discomfort directly. The following symptoms should raise the level of suspicion for a head lice infestation:
- Itching (“pruritis”): Caused by an allergic reaction to lice bites. When lice feed, they inject a small amount of saliva into the skin. Over time, the host can develop an immune reaction to the saliva which results in inflammation and itching. It may take four to six weeks for this reaction to occur in people infested for the first time. However, itching may not be present in all cases.
- Sores on the head: Rarely, scratching can lead to abrasions on the skin, allowing bacteria to enter and possibly lead to infection. In severe cases, lymph nodes around the head, neck and underarms can become swollen.
- Tickling sensation: Lice movements in the hair may be felt by some infested individuals.
- Sleeplessness and irritability: Lice are more active at night, possibly disrupting sleep.
Some people with head lice infestations have no symptoms. A lack of symptoms does not mean a lack of head lice.
Diagnosis and Testing
Head lice may be brought home after a person has had direct head-to-head contact with someone who has an active head lice infestation. This is most often a close family contact or friend. Lice may spread rapidly to others throughout the home because of the close contact of family members. Whenever one person in the family has been identified to have lice, everyone living in the home should be checked. Any friends, family members, or other people who have had close head-to-head contact with the infested person over the previous week should be notified so they can be checked for head lice as well.
Careful inspection of the hair and scalp is necessary to see if a person has head lice. Head lice are best identified by inspecting the hair and scalp for live lice or nits (eggs attached to the hair shaft close to the scalp). The standard for identifying head lice is finding a live louse on the head. Lice and nits are most often found at the nape of the neck and above and behind the ears. (Read more about careful inspection)
How do you treat head lice?
There are numerous ways to treat head lice infestations, including:
- Treatment with pediculicides (lice medications or shampoos)
- Manual removal (nit combing)
- Alternative or natural methods
Treatment should be considered only if lice or viable eggs are observed.
Generally, a combination of pediculicides (lice medications or shampoos) and nit combing is the most effective.
It is very important to treat all affected members in a household at the same time. If this is not done, re-infestation from one person to another in the home can easily occur. Remember to follow the label directions of any product or medication you use for treating head lice, many products can be harmful if used incorrectly.
How do you prevent head lice?
The following are steps that can be taken to help prevent and control the spread of head lice:
- Avoid head-to-head (hair-to-hair) contact during play and other activities at home, school, and elsewhere (sports activities, playground, slumber parties, camp).
- Do not share clothing such as hats, scarves, coats, sports uniforms, hair ribbons, or barrettes.
- Do not share combs, brushes, or towels. Disinfest combs and brushes used by an infested person by soaking them in hot water (at least 130°F) for 5–10 minutes.
- Do not lie on beds, couches, pillows, carpets, or stuffed animals that have recently been in contact with an infested person.
- Machine wash and dry clothing, bed linens, and other items that an infested person wore or used during the 2 days before treatment using the hot water (130°F) laundry cycle and the high heat drying cycle. Clothing and items that are not washable can be dry-cleaned OR sealed in a plastic bag and stored for 2 weeks.
- Vacuum the floor and furniture, particularly where the infested person sat or lay. However, spending much time and money on housecleaning activities is not necessary to avoid reinfestation by lice or nits that may have fallen off the head or crawled onto furniture or clothing.
- Do not use fumigant sprays or fogs; they are not necessary to control head lice and can be toxic if inhaled or absorbed through the skin.
To help control a head lice outbreak in a community, school, or camp, children can be taught to avoid activities that may spread head lice.