Head Lice

Ten Common Questions Asked About Head Lice

Adapted from the 2002 Position Statements of the
Canadian Pediatric Society and American Academy of Paediatrics
Endorsed by the Simcoe County Pediatricians and The Simcoe Muskoka District Health Unit

1. HOW ARE HEAD LICE IDENTIFIED?

The most common symptom of head lice is itching. This is caused by sensitization to lice saliva: a louse feeds by injecting tiny bits of saliva and taking tiny amounts of blood from a human scalp. With a first exposure to head lice, presence of just a few lice, or people who are less sensitive to lice saliva, there may be no complaints at all.

To make the diagnosis of head lice, you need to examine the hair and scalp very carefully to find a live louse. Adult lice are usually grey and about the size of a sesame seed (2-4mm). They can be very tricky to spot because they can crawl and hide in the hair, but are most often seen along the hairline behind the ears and at the back of the neck.

It is usually easier to find the casings for the eggs laid by the lice - these are called "nits" and are even smaller than the lice, oval in shape, and they vary in colour. Lice lay their eggs within three or four millimetres of the scalp so the eggs will stay warm and there will be food for the baby louse ("nymph") when it is hatched about a week later. Lice attach the nits (containing the eggs) to the hair with a strong glue-like substance which means the empty nits stay stuck to the hair even after the eggs have hatched or been killed with chemicals. As the hair grows, it carries the empty nits further away from the scalp - these empty shells CANNOT spread lice to the same child or others. The American Academy of Pediatrics says that, "nits found more than 1 cm from the scalp are unlikely to be viable" (AAP p.638).

An important difference between nits and other things found in hair (such as dandruff, scabs, dirt, hairspray droplets, etc) is that nits cannot be flicked off the hair easily, nor can they be slid up and down the hair shaft.

2. HOW ARE HEAD LICE TRANSMITTED?

Head lice can only crawl. They CANNOT hop, jump, or fly. They ONLY survive on humans. Head lice are transmitted primarily by direct head-to-head contact. They are most common in children between the ages of three and twelve years. Hair length and frequency of hair brushing or shampooing do not seem to make a significant difference.

Head lice rarely survive more than a day away from the scalp (they get cold and hungry!). Also, their eggs cannot hatch if they are not at the right temperature and the baby louse cannot survive without food nearby. As a result, indirect transmission of head lice by contact with personal belongings is MUCH less likely to happen. It is still recommended that parents discourage their children from sharing brushes, combs, and hats.

3. WHAT TREATMENT IS RECOMMENDED?

The Canadian Paediatric Society concludes, "there appears to be no satisfactory method to get rid of an infestation apart from chemical treatment" (CPS p.237). The American Academy of Pediatrics agrees that the only treatments for which there is good evidence to show that they work are the chemical shampoos ("pediculicides").

In Canada, a number of different pediculicides are available over the counter and on prescription. They are all potentially harmful if used improperly; so it is VERY IMPORTANT to read the instructions carefully, discuss their use with a pharmacist or physician, and use ONLY AS DIRECTED. They should never be applied to broken skin, and should be stored out of reach of children.

It is important to note that experts are now recommending that the pediculicide shampoo treatment should be repeated in seven to ten days because some newly laid eggs may have survived the first round. By treating again seven to ten days later, any surviving eggs will have hatched but not have had time to lay any more eggs: the repeat treatment will kill these new lice.

4. WHAT DO WE DO AFTER WE USE THE RECOMMENDED TREATMENT?

Both the Canadian Pediatric Society and American Academy of Pediatrics are very clear that it is NOT NECESSARY to remove nits after appropriate treatment with a pediculicide shampoo in order to prevent spread. Most of these nits will contain eggs that have been poisoned by the pediculicide. The few nits that may contain surviving eggs will hatch over the next week and the few new lice will be killed in the repeat application of the pediculicide shampoo, as described above.

You may wish to pick the nits out after using the shampoo in order to decrease "diagnostic confusion" (where dead nits might be mistaken for active infestation) or for cosmetic reasons. The American Academy of Pediatrics notes that some experts recommend removal of nits within a centimetre of the scalp to decrease that small risk of a few nits surviving to hatch - remember that solving this problem is also the purpose of the second treatment seven to ten days after the first.

If live lice are found within 24 to 48 hours, the Canadian Pediatric Society recommends immediate re-treatment with a DIFFERENT pediculicide shampoo, and then repeat treatment with this second shampoo seven to 10 days later. In this unusual circumstance, discussion with a pharmacist or physician is prudent.

5. WHO ELSE NEEDS TO BE TREATED?

It is important to carefully check the hair and scalp of everyone who may have had direct contact with a child who has live lice. These other people do not need treatment UNLESS live lice or nits within a centimetre of the scalp are found.

The exception to this rule is anyone who shares a bed with the child who has lice: both the Canadian Pediatric Society and American Academy of Pediatrics recommend that bedmates should be treated on the assumption that they have lice, too.

6. WHAT ABOUT OBJECTS THAT MY CHILD'S HEAD MIGHT HAVE TOUCHED?

There is little evidence to suggest that sharing hats, brushes, and other personal articles can spread head lice. However, heat will kill any stray lice and families may wish to wash personal articles in hot water for at least ten minutes. Drying items at high temperatures, or storing them in plastic for ten to fourteen days, will also kill lice.

7. DO WE NEED TO FUMIGATE OR SPRAY?

Spraying (fumigation) is NOT recommended. If families are concerned about carpets, furniture, or carseats, vacuuming should be sufficient.

8. HOW SHOULD A CASE OF HEAD LICE IN A SCHOOLCHILD BE HANDLED?

The emphasis should be on confidentiality, not embarrassing the child or family involved, and ensuring appropriate treatment is undertaken. A child found to have active head lice has likely had them for some time: there is no need for the child to be removed from the class on the day of diagnosis, although close direct head contact with others should be quietly discouraged.

The Canadian Pediatric Society recommends the following steps for case management of a child with head lice:

• Confirm the presence of head lice by detection of live lice and/or nits.
• Stress to the parents the importance of using a pediculicide shampoo according to the instructions supplied with the package, repeating the procedure in seven to 10 days, and properly using and storing the product.
• Reassure the parents that head lice are NOT responsible for the spread of any disease and do not reflect personal cleanliness or hygiene practices.
• Inform parents that indirect transmission does not play a major role in the spread of lice. Some parents may wish to wash combs, brushes, headgear, pillowcases and towels in hot water.
• Ensure that contacts of an affected child, including family members, schoolmates and day-care centre contacts, are examined and treated if lice/nits are found. Bedmates of the affected child should be treated regardless.

Both the Canadian Pediatric Society and American Academy of Pediatrics agree that the evidence DOES NOT SUPPORT the use of "no-nit policies" for return to school or day-care. They recommend that children can return to school once treated with an effective pediculicide.

1. WHAT ABOUT ROUTINE SCREENING OF STUDENTS AT SCHOOL?

Unfortunately, this does not seem to be the answer. The Canadian Pediatric Society and American Academy of Pediatrics found that these programs have NOT been shown to have a significant effect on the incidence of head lice in schools, and are not cost effective.

2. HOW CAN WE PREVENT THE SPREAD OF HEAD LICE?

The American Academy of Pediatrics responds:

"It is probably impossible to totally prevent head lice infestations. Young children come into close head-to-head contact with each other frequently. It is prudent for children to be taught not to share personal items such as combs, brushes, and hats. In environments where children are together, adults should be aware of the signs and symptoms of head lice infestation, and affected children should be treated promptly to minimize the spread to others." (AAP p.639)

To deal with the problem of head lice, responsibility needs to be shared by parents, school and community health professionals.

Parents/guardians should learn how to recognize head lice and routinely check their children. When a child has head lice the parent/guardian should notify the school. Parents/guardians may wish to provide education and support to other parents in their local community.

Schools should have basic knowledge about prevention and treatment of head lice. Notification of, or reminders to, parents regarding head lice is a school responsibility.

When there are repeated incidents of head lice, the principal may consult with the Simcoe Muskoka District Health Unit through Health Connection for written information about head lice; situational management advice; and consultation for parents/school staff in the implementation of training sessions.

The facts of lice Position statement of the Canadian Peadiatric Society regarding head lice

REFERENCES:

Infectious Diseases and Immunizations Committee, Canadian Pediatric Society; "Head lice infestations: A persistent itchy `pest' "; Paediatrics & Child Health 1996 1(3): 237-240. Reaffirmed April 2002.

Frankowski BL; Weiner LB; Committee on School Health; Committee on Infectious Disease; "Head lice: American Academy of Pediatrics Clinical Report"; Pediatrics September 2002 110(3): 638-643.