What Are Head Lice?
Head lice are a parasitic insect that lives between hair, often found on the head. While most commonly found in the hair, lice can also live on eyebrows and eyelashes. Each louse lives close to the human scalp so that it can easily feed on blood throughout the day.
Lice travel by crawling, and are unable to jump or fly. They have claws that are suited to grasping individual hairs, which is how they anchor themselves on the head. While a louse may travel around the head, it is typically locked on to a strand of hair when not in motion. Currently African-Americans are at the least amount of risk of infestation. It is believed that lice have adapted to having a claw size and diameter that is better suited for holding on to the hair of other races.
Lice infestation is extremely common in the United States. The Center for Disease Control estimates that six to twelve million children between the ages of three and eleven, become infested with lice each year.
Head lice exist in three stages: the egg, the nymph, and the adult stage.
The egg of a louse is extremely tiny and is laid very close to the scalp, attached to a strand of hair. It is sometimes called a nit. The egg is an oval shape and is approximately the size of a knot in a piece of thread. The egg may be difficult to see, as the color ranges from white to yellow, to a color that blends with the hair of the infested person.
Because of their size and non-descript appearance, it is not uncommon to mistake a louse egg with dandruff, dry skin, or a scab. Once the egg is laid, it will take approximately eight to nine days to hatch. While most eggs are laid within 1/4 of an inch from the scalp, eggs can get laid further up the hair shaft. However, eggs further than 1/4 of an inch from the scalp are less likely to hatch.
The nymph is a juvenile louse, after it hatches from the egg but before it reaches adulthood. Nymphs look exactly like a fully matured louse with the distinction of being significantly smaller than an adult. The nymph will feed on blood like the adult, and within approximately ten days, the nymph will reach adulthood.
Adult lice are now fully grown, approximately 25 days after the egg was laid. The adult louse is approximately the size of a sesame seed and will appear between a tan color and white. The adult lice will feed on blood, much like the nymph, and will live for approximately 30 days while on the head of a human. If the louse falls off the head, it will not live more than one to two days.
Adult female lice lay approximately six eggs per day.
How Do You Get Head Lice?
Because head lice move by crawling, those in close contact with a person infested with lice are at greatest risk of becoming infested. Other forms of contact such as sharing hats, scarves, or coats, as well as items such as brushes and combs, similarly present an increased risk of infestation.
The most common group of people to become infested with head lice are young school-aged children. This is because there is a higher likelihood of close contact between children, or shared objects that facilitate the transfer of lice from person to person. While it is less common to have lice hitch a ride on clothing, it is possible. Again according to the CDC, the following are identified as potential risk for transmitting lice:
- Sharing brushes, combs, hair accessories
- Sharing hats, helmets, scarves, or coats
- Sharing towels
- Items close to the infested person such as clothing or stuffed animals
- Coming in contact with rugs, carpet, bedding, furniture that an infested person has been in recent contact with
What Are The Symptoms Of Head Lice?
Head lice are almost always located on the head, particularly found behind the ears and near the neck. While they can live in eyelashes and eyebrows, it is less common to find them there.
There are several signs and symptoms of a head lice infestation.
- Tickling or tingling feeling on the head - this may feel like something moving in the hair
- Itching - allergic reaction to the bite
- Scabs on the head - caused by scratching
- Infected sores - bacteria on the body may infect a sore opened by scratching
- Difficulty sleeping - lice are nocturnal
- Irritability or difficulty concentrating
- The appearance of any louse or egg
Everyone has a different level of sensitivity to the louse's saliva. This can cause red bumps, and itchy skin, which typically leads to scratching. Similar to chicken pox, reducing your child's tendency to scratch is important.
Head lice diagnosis is typically made after a visual inspection of the head, or after a live insect is found. To assist you in locating a live louse, a magnifying glass or a nit comb (a very very fine toothed comb) may be helpful. While you may find evidence of an egg or egg casing, or a nymph cemented to a strand of hair, such evidence does not confirm a diagnosis, although it strongly suggests a lice infestation.
If you find nits located further than 1/4 of an inch from the scalp coupled with no evidence of live insects, the infestation was likely active in the past but is no longer active, requiring no treatment.
Diagnosis can be made by anyone who observes the live insects, or by a health care professional. After a diagnosis is made, it is not required that you report the infestation to the CDC; however, schools may have a policy related to head lice. Your local Health Department may have further information or recommendations related to head lice.
How To Treat Head Lice:
It can be difficult to remove lice eggs because they are firmly adhered to the strand of hair. Further they can be difficult to remove because of their claws.
General treatment for head lice includes commercially available or prescription shampoos. It is important to not use a 2-in-1 shampoo/conditioner prior to treatment. You also should not wash your hair for one to two days after treatment. Follow the instructions on the package regarding application and rinsing of the hair. For long hair, more than one bottle may be required to adequately treat hair.
After treatment, put on clean clothing.
Monitor lice after eight to twelve hours post-medication. The lice should be moving more slowly or be dead. If so, you do not need to apply a second treatment.
If there is no change in the lice, retreat, possibly with a different brand of shampoo.
The kit should come with a nit comb - use that to comb the hair thoroughly to check for eggs or lice.
After treatment, check and comb the hair every few days, and continue checking for up to three weeks to prevent reinfestation.
Machine wash and dry clothing, bedding, and other objects in close proximity with the infested person. Be sure to use high heat and hot water. Soak combs and brushes in hot water (over 130 degrees F). Vacuum the floor and furniture.
FOR CHILDREN UNDER 2: DO NOT use lice shampoos or medications on children two and younger. Instead comb your child's hair after washing every three to four days for two weeks AFTER the last live louse is found. This method is also acceptable for those who do not want to use a pesticide shampoo.
Dos And Don'ts:
- Do wash and condition your child's hair prior to combing.
- Don't use a shampoo/conditioner combination before using a nit shampoo.
- Don't wash hair one to two days after treatment.
- DO NOT use sprays or pesticides on hair.
- Don't mix lice medications.
- Do consult with your doctor if you have applied two to three medication treatments to hair that has not resolved the infestation.
- Do treat every member of the household for lice, even if no lice have been observed.
If you have lice, you are dirty or have poor hygiene.
Head lice are transmitted from person to person, regardless of their personal or at-home situation. Poor hygiene or living situation have no bearing on who becomes infested with lice.
Head lice spread disease.
There is no evidence to suggest that head lice spread any type of disease. While it is possible that a sore may become infected, that is the result of an open wound from scratching, and bacteria already present on the body.
Head lice spread to and from pets and animals.
Head lice cannot live on animals, which are not believed to be carriers or responsible for the transmission of head lice among people.
Swimming kills head lice.
Lice can live in water for several hours and are not immediately killed by chlorine or other chemicals used to treat pool water. However, lice are unlikely to be transmitted in pool. Sharing towels, brushes, etc after swimming are more likely ways that lice may be transmitted.
Only poor people get lice.
Lice is equally as likely to be acquired by everyone who is exposed to lice. The highest-risk group are children because of their close proximity to one another as well as their tendency to share items.
Information For Schools:
Because the target population who become infested with head lice are school-aged children, schools should be familiar with head lice and how to respond to notification of an infestation. Many schools have a "No-nit" policy that outlines specific requirements for your school.
IF A CHILD IS FOUND TO HAVE LIVE LICE: The child does not need to immediately go home. At the end of the school day the child can be treated at home for the lice infestation and return to school after the treatment has been applied. The treatment will kill living "crawling" lice.
"No-nit" policies are losing popularity, and the American Association of Pediatrics and the National Association of School Nurses actively advocate against these policies, which generally require that a child stay out of school until they are nit free. Specific reasons cited for this position include:
- Most nits are not viable and thus not transmittable.
- Because they are cemented, nits are not likely to transmit from person to person.
- Absenteeism represents a larger issue than the low likelihood for transmission.
- Misdiagnosis is common.
Additional Head Lice Resources:
HeadLice.org - This is a comprehensive website with general information, news, articles, treatment, signs and symptoms related to head lice, scabies, and other infestations. Their kids website is located here.