1. Cooties All About Head Lice LT Greg Gorman, MC, USNR Camp Lejeune, NC

2. Lice is a Big Deal Infests 6-12 million per year, mostly school-aged kids Does not carry disease, but carries huge social stigma Biggest problem: Parental Phobia School Hysteria 3. Know Your Enemy Pediculus humanus var capitis

A blood-sucking insect whose only environment is the human scalp(warm, vascular)

East a blood meal every 4-6 hours

If not on scalp, lice die within 24 hours

4. Know Your Enemys Reproductive Cycle

This determines treatment, how to interpret findings and how to combat parental/school myths and phobias

Egg Nymph Adult 5. Lice Eggs Several embryos in one egg Incomplete nervous system (not affected by drugs) Need heat to hatch, so always 1-3 mm from scalp Glued to hair shaft with chitin Have an operculum at top for air and humidity Live eggs are hard to see close to scalp and translucent Empty eggs (nits) are easier to see further from scalp as hair grows inside of egg is reflective Hatches after 7-12 days 6. Lice Nymphs

Smaller than adults

Molts 3 times in 8-9 days

Cannot reproduce

Not easily transmitted

7. Adult Lice

Big as a sesame-seed; reddish-brown

Cannot fly or hop

Cling to hair shaft with 6 claws

Claws evolved to conform to human scalp hair thickness

Lay eggs 1-2 days after becoming adults

Life-span is 30 days

8. Host Factors

Lice claws evolved to fit circumference of human hair

Lice are less common in African-Americans, who have oval hair shaft

Crowded living conditions

Hair length isnota factor

(just easier to see nits in longer hair)

Personal hygiene doesnotplay a role

9. Kids are more susceptible

10% of school children have lice

Have more physical contact with peers

10% of infestations occur at school

Usually close friends transmit lice

Girls > Boys (more close contact)

10. Diagnosis of Lice (What to Do When the School Sends Your Kid Home)

Look for a live louse on the scalp

Hard to See

78% of infested kids had 1-10 lice

0.3% had more than 50 lice

Use a comb with 0.3 mm teeth and use a magnifying glass for 5 minutes

11. What if you Find Nits?

Nits by themselves are not signs of infestation

(especially after treatment)

Could be hatched already or filled with dead embryos

If nits are close to the scalp and treatment hasnt been tried, its probably active

12. Other Signs of Infestation

Soiled pillows (from lice feces)

Symptoms not typical

Of 501 infested kids,

44% were asymptomatic

36% had pruritus

Itching usually requires sensitization

thousands of bites (~ 3-8 months after infestations starts)

13. Comparison of Head Lice Treatments 14. Lindane

Oldest drug (Kwell)

No longer on market

Kills lice by interfering with their CNS

Patients can sometimes feel lice convulsing

Requires prescription since inappropriate use can cause seizures

Slower and less effective than other agents

15. Pyrethrin & Permethrin

Derivatives of a natural insecticide derived from chrysantheums

Disrupt Na-channels in CNS

Very low systemic absorption with OTC preparations, but still classified as neurotoxic

Lasts long time by binding to hair, perhaps contributing to resistance

16. How to Treat (Tricks of the Trade)

Safety :Rinse in sink, not shower

Apply todryhair: the eggs close their operculum in water

Repeatin 7-12 days

After treatment, rinse with 1:1 vinegar:water mixture to dissolve glue and then remove eggs with 0.3 mm tooth comb with 1 1/2 inch teeth

Inspect scalp 48 hrs after treatment to determine what type of lice, if any, are present

• A few large lice(maybe resistant)

• Many sizes of lice(ineffective treatment)

17. More Tricks of the Trade

Anti-histamines may be useful if itching is severe

• Tell parents that itching may occur after treatment and that it is reaction to dead lice and is not a sign of re-infestation

Cleaning & washing inanimate objects

• Probably plays no role in getting rid of lice, but if they must...

• • Drying clothes for 20 minutes before washing them

• • Seal clothing in bags for 14 days

18. Questionable Folk Treatments

Kerosene: dangerous, ineffective

Smothering: layers of vaseline, olive oil, mayonnaise, or shower cap overnight.Probably not effective and not ovicidal

19. Can Lice Be Resistant?

Incorrect use accounts for majority of treatment failures !!!However,...

Piperonyl-butoxide was added as an inhibitor of pyrethrin-inactivators

In UK, effective doses of drugs increased dramatically since 1948

• Lindane: up 200x(Burgess, Advan Parasit 36, 1995)

• Permethrin: up 20x(Maunder, J R Soc Health 111, 1991)

In Israel, clinically significant resistance within 3 yrs of permethrins introduction(Mumcuoglu, Med Vet Entomol 9, 1995)

In Czech Republic, effective dose of permethrin rose 500x between 1981 and 1992(Rupes, Cent Eur J Public Health 3, 1995)