Bugs that May Affect Children in the Pre-school Environment

David N. Gaines, Ph.D.Public Health Entomologist

Virginia Department of HealthDivision of Environmental Epidemiology

How to deal with Head Lice on Children in a Pre-School Setting

Photo by Gilles San Martin

The feet (claws) of a head louse are best adapted to crawling rapidly along and through hair.

Head lice will die if separated from the human head for more than a day, so they avoid leaving the head if possible.

Head Lice Environment

Head lice evolved to live on human heads and cannot survive in any other environment, on any other part of the human body, or any other animal.

The environment on a head provides the perfect combination of warmth, humidity, food (blood), and a matrix (hair) to live on.

How Head Lice SpreadHead lice are most commonly spread from person to

person by direct and prolonged head to head contact.

It is much less common for head lice to be spread from inanimate objects to a person. When head lice are spread on objects it is usually by:

Other items that have been in recent, prolonged contact with infested hair (coat collars, couch cushions, pillows, stuffed toys, carpet).

Head gear (hats, scarves, hair ties, barrettes, head phones, brushes, combs), or by:

Head Lice on Children

Head lice infestations are more common on young children than adults because children have a much higher degree of physical, interpersonal contact.

Girls are more predisposed to head lice than boys because girls are more likely have direct prolonged head to head contact , and share things like hats, hair ties, combs, and clothing.

African Americans are less likely than other races to get a head louse infestation due to the structure of their hair.

Head Lice on Children

Head lice infestations are not related to a child’s level of cleanliness or hygiene .

As head lice can spread quickly in a kindergarten / pre-school setting, it is important to be vigilant for children with signs of an infestation and resolve the problem before it spreads .

Infestations are primarily due to a child’s unfortunate contact with another carrier of lice.

Head Lice Biology and Life Cycle Adult female head lice lay eggs (nits) on a strand of hair

right next to the scalp.

Eggs are firmly glued to the hair.

By the time eggs hatch 8 – 9 days later, the hair has grown out about ¼ inch from the scalp.

Eggs (nits) found on hair more than ¼ inch from the scalp are empty egg shells (have already hatched).

Head Lice Biology and Life Cycle Nymph stage lice hatch out of the eggs and molt through

three progressively larger nymph stages.

About 9 - 12 days after hatching from eggs, nymph stage lice become adults.

Nymph1

Nymph2

Nymph3 Adult

MaleAdult

FemaleCDC Public Health Image Library

Head Lice Biology and Life Cycle

Adult lice measure from 1/16” to 1/8” (inch) in length.

Mated adult females live for about 30 days, can lay up to six eggs a day, and must have a blood meal each day.

Photo by Gilles San MartinPhoto by Gilles San Martin

Adult Female

Adult Male

Louse on Q-tip

Photo by Eran Finkle

Beginning a Head Louse Infestation

A head louse infestation cannot be started by a single louse unless that louse is a mated female.

By that time, there would be at least 12 to 24 nymph stage lice feeding on the scalp as well as the adult female.

A child infested with a single mated female would probably not begin to notice the infestation until about 10 - 12 days after the louse climbed aboard.

The initial signs of a head louse infestation are a tickling or itchy feeling in the scalp and difficulty sleeping (head lice are more active at night).

Other Signs of a Head Louse Infestation

Nits (eggs) visible in hair.

As head lice are small and move through the hair very quickly, a magnifying glass and strong light will be needed to observe them.

Nymph and adult lice scurrying around.

Head lice can be found anywhere in the hair as well as on eyebrows, but are most often observed in the hair behind the ears, on the back of the head, and in hair at the neck-line.

Other Signs of a Head Louse Infestation

Observing active lice and new nits requires using a lamp, magnifying glass, and comb to look through hair to the scalp level.

Prevent head to head contact among children during play.

Transmission Prevention

Prevent the sharing of head gear, combs, hats, clothing, beds, pillows, or couches, among children.

Vacuum any carpet, or sofa cushions that have come into contact with an infested child’s head.

Launder any clothing, blankets, sheets or pillow cases that have been used by an infested child (wash in hot water and dry on high heat on a daily basis) .

Disinfect any combs, brushes, or hair ware used on an infested child (in hot water [130°F] for 5-10 minutes) .

Prevention – School “No-Nit” Policies

School “no-nit” policies are controversial.

Some public health advocacy groups say that “no-nit” policies have not reduced louse infestation rates, and have disrupted student attendance and education.

Due to this disagreement, no-nit policies are instituted by some state or local school boards, but not by others.

More studies are needed to understand the cost/benefit analysis of no-nit policies.

Visible nits in hair is not evidence of an active louse infestation, and the absence of visible nits does not mean there are no head lice present.

Pyrethrum (Pyrethrins) Shampoos - Kill nymph and adult lice, but have no effect on eggs.

Chemical Treatments – Commercial Remedies

Re-treatment is necessary in 9 days to kill the nymphs that hatch out of unaffected eggs.

Pyrethrins have negligible toxicity to people, but allergy to this product could be a concern for some people.

Some lice may be resistant to pyrethrum treatments.

Permethrin Lotion 1% (Nix) - Kills nymph and adult lice and has residual activity, but has no effect on eggs.

Re-treatment in 9 days is necessary to kill the nymphs that hatch out of unaffected eggs.

Permethrin has very low toxicity to people, but is not recommended for use on children under 2.

Use of shampoos with conditioners in the week after treatment may reduce residual treatment effectiveness (use baby shampoo only).

Some lice may be resistant to permethrin treatments.

Chemical Treatments – Commercial Remedies

Benzyl Alcohol Lotion 5% (Ulesfia lotion) - Kills nymph and adult lice, but has no effect on eggs.

Re-treatment is necessary in 9 days to kill the nymphs that hatch out of unaffected eggs.

Benzyl alcohol is non-toxic and may be used on babies as young as 6 months old, but caution is required in use due to potential for eye irritation, or for skin irritation in sensitive people.

Chemical Treatments – Commercial Remedies

Malathion Lotion 0.5% (Ovide) - Kills eggs, nymphs and adult lice and has residual activity.

Re-treatment is recommended in 9 days to kill any lice or eggs that may have escaped treatment.

Malathion can be toxic to people and may cause irritation to eyes and skin, and is not recommended for use on children under 6.

Use of shampoos with conditioners in the week after treatment may reduce residual treatment effectiveness (use baby shampoo only).

Chemical Treatments – Commercial Remedies

Nit and Lice Combing and Removal

As there is potential for treatment failure due to louse resistance to some insecticide products, combining topical chemical treatments with nit and lice combing activities is advisable.

Chemical Treatments – Commercial Remedies

When using chemical treatments, strict adherence to label instructions is essential for maximum efficacy and to minimize the risk of toxic reactions!

A white vinegar rinse (30 to 60 minutes) - Loosens glue on eggs, and facilitates egg removal by nit comb.

Nit and Lice Combing and Removal

Combing all nits and lice out of hair can be done instead of chemical treatments, or as a supplement to improve the efficacy of chemical treatments.

If used in place of pesticide treatments, it must be done very thoroughly and frequently (should be done at no more than two-day intervals for several weeks).

A thorough removal of all nits may be necessary in school districts that have no-nit policies.

Non Toxic Treatments – Nit and Louse Removal

A thorough combing out of nits and lice may require up to an hour or more of time – depending on child’s hair length.

Lice Out™ Gel - When applied to hair, it gums up and slows the movement of nymphs and adult lice so they can be easily combed out.

Hair is parted into four sections and each section is worked methodically with the comb from one end to the other.

Some nit and louse combs may be better than others (some recommend combs made by Lice Out™ or LiceMeister™ ).

Home Remedies – Oil Based Treatment

Hair is combed out with nit comb and then shampooed several times to remove remaining oil.

Oil or mayonnaise is worked into hair, oiled hair is covered with a shower cap; shower cap/oily hair is briefly heated with hair dryer; oil is left in place for at least 30 minutes.

The “oil based treatment” is a popular home remedy that is said to suffocate lice and eggs.

Although popular, the oil treatment’s efficacy has not been tested in a controlled study.