NHM Health Focus:
As parents and children prepare for the 2009-2010 academic school year, the National Pediculosis Association advocates the early screening of head lice and nits (head lice eggs) with safe and healthy tools demonstrated to keep children nit and anxiety free.
"The most effective solution is normal hygiene plus frequent combing of the hair. Fine-tooth combs are effective for removing the lice, and frequent grooming with a normal comb also controls the infestation by removing some lice and inflicting injury on others which cling tenaciously to hairs in their efforts to resist being dislodged. Lice do not regenerate lost limbs, and any louse which has lost a leg due to combing (or scratching) will die very shortly thereafter. In some societies, head lice are controlled by applying oil to the hair. The oil suffocates the growing louse by sealing the air vents in the operculum of the egg casing."
Although head lice may be found on any part of the scalp, they most commonly are found in the retroauricular scalp (behind the ear). Eggs depend on body warmth to incubate, so nits are attached to the hair shafts just above the level of the scalp. Human scalp hair grows at a rate of approximately 0.37 mm/day. Nits found several millimeters from the scalp are nonviable empty egg cases. They indicate chronic infestation.
Adequate light is a must when examining hair for nits and mature lice. In addition, some report that wetting the hair before combing makes it easier to to spot headlice. (WebMD)
Once lice are discovered, there are a number of control and treatment options. The options, summarized below from Dr. Richard Pollack of the Harvard School of Public Health include:
These methods of head lice control and treatment and answers to frequently asked questions are described more fully on the Harvard School of Public Health website.
- Mechanical removal This is a non-toxic and effective but time-consuming method of louse removal. "An infestation may be eliminated by combing each day to remove the live lice (including those that have hatched since the previous day). Comb daily until no live lice are discovered for about two weeks." Some people report that water, vegetable oils or hair conditioners help lubricate the hair and ease the combing process; others report that these lubricants make it more difficult to see the eggs.
- Pyrethroid insecticides As with any insecticide or drug, read and follow the label directions. Because these products seem to have limited ovicidal (egg-killing) activity, a second treatment is often necessary about 10 days later to target lice that hatch after the initial treatment.
- Non-pyrethroid insecticides Two other pesticides are available by prescription.
- Essential oils Experts do not have the data to support the effectiveness of these products.
- Enzyme treatments Enzyme treatments advertise that they "dissolve" the very high quality 'glue' head lice use to attach their nits to individual hairs. The effectiveness and safety of these products has been questioned by experts.
- Antibiotics Use of antibiotics to treat head lice infestations is not recommended because such antibiotic use may lead to antibiotic resistance in other microorganisms that accelerate the emergence or spread of bacterial resistance, thereby diminishing the usefulness of these antibiotics.
- Antiparasitic drugs At this time, no anti-parasitic drugs have been approved for the treatment and control of headlice.
- Suffocating agents Food-grade oils or hair gels are used in attempts to smother lice on the scalp. This method has worked for some.
- Heat Hot air from a hair dryer may kill head lice and their eggs, but it may also burn the hair and scalp.
- Freezing Freezing is an effective way to kill lice on toys and other objects that cannot be treated with the heat of a dishwasher, hair dryer or clothes dryer.
- Haircuts Lice eggs (nits) cannot cling to to a bald head and short hair makes it easier to see the lice. However, short hair or a bald head may not be what the style choice of the infested person.
- Hair soaps, bleaches and dyes Data is lacking to assess the efficacy of these products against lice.
Access Excellence @ the National Health Museum (AE@NHM)
offers the following resources useful for understanding topics related to head lice issues:
Health Headquarters: Question of the Week -