American Academy of Pediatrics Guidelines for the Prevention and Treatment of Head Lice Infestation

September 1, 2004
Barbara L. Frankowski, MD, MPH

Supplements and Featured Publications, Definitive Management of Head Lice in the Era of Pediculicide Resistance, Volume 10, Issue 9 Suppl

The American Academy of Pediatrics (AAP)established diagnosis and treatment guidelines forpediculosis in 2002. Ideally, diagnosis should bebased on the observation of a live louse. The presenceof nits is also used by many people to positivelydiagnose an infestation, although a nit locatedfarther from the scalp than 1 cm is unlikely to beviable. Other material on the scalp may be mistakenfor nits, leading to misdiagnosis.

Because lice are not associated with serious medicalproblems, the primary consideration of the AAPregarding treatment is the safety of pediculicides andother products used to treat head lice. From a pediatrician'sperspective, no significant risk is acceptable.Over-the-counter (OTC) pyrethroid products (pyrethrinand permethrin) are commonly used by parents to treattheir children and are generally considered safe formost people. Pyrethroids are not completely ovicidal,however, so a second application is required. Misuseand overuse of these products have contributed to thedevelopment of resistance. Prescription productsinclude permethrin 5%, lindane, and malathion 0.5%.Resistance to permethrin 5% and lindane has beendocumented. In addition, lindane is associated withserious adverse events and should be used with cautiononly in a select population. Malathion 0.5% isabout 98% ovicidal, and no resistance has beenreported. Malathion is highly effective, but AAP guidelinesnote that the product is flammable and seriousadverse effects can occur with ingestion. Very fewcases of ingestion have occurred, and no reportedcases of flammability, but children being treated withmalathion should be carefully supervised, and thispediculicide should not be used unless treatment withOTC products has failed.

AAP guidelines also state that no-nit policies inschools are detrimental, causing lost time in theclassroom, inappropriate allocation of the schoolnurse's time for lice screening, and a response toinfestations that is out of proportion to their medicalsignificance. Accurate diagnosis, safe treatmentoptions, and a common-sense approach to managinginfestations in schools are recommended.

(Am J Manag Care. 2004;10:S269-S272)

Head Lice: Pediatrician's Perspective

Safety and efficacy are the key concernsof the American Academy of Pediatrics(AAP) when the organization establishestreatment guidelines. During the developmentof treatment guidelines for pediculosis,which has no significant associatedmorbidity and no mortality, the primaryconcern of the AAP was the safety of productsused to treat infestations. Other informationincluded in the guidelines describessocial and economic consequences of liceinfestation. Specifically, although head licedo not cause medical problems, infestationsdo cause significant embarrassment andsocial stigma, unnecessary days lost fromschool because of no-nit policies, and directcosts of treatment, as well as indirect costsfrom lost productivity. In consideration ofthese issues, the AAP published its clinicalreport on the management of head lice in2002 in an attempt to clarify issues of diagnosisand treatment, and to make recommendationsfor managing head lice in theschool setting.1

Diagnosis

The first challenge in effectively managinghead lice infestation is obtaining a correctdiagnosis. Observing live lice is the goldstandard of diagnosis, but lice are difficult tosee, and they can crawl 6 to 30 cm perminute. Within a school setting, a nurse whohas only a minute per child to screen maymiss a louse that is well camouflaged or thathas crawled to another part of the child'shead during examination. Nits may be easierto spot because they are stationary andare generally laid within 1 cm of the scalp.The nape of the neck and behind the earsare good places to look for nits. Nevertheless, nits are small and difficult to seewith the naked eye, especially if lighting ispoor. It is important, also, to distinguish livenits from empty egg casings or other materials.Dandruff, hair casts, scabs, dirt, andother insects are sometimes mistaken forlice, even by physicians and nurses.1,2

General guidelines for assessing the viabilityof a nit include its location and appearance.Typically, a nit located farther fromthe scalp than 1 cm is unlikely to be viable,although lice in warmer climates may layeggs farther down the hair shaft.3 Also, aviable nit develops a circular, eyelike markingcalled an eyespot several days after beinglaid. An eyespot can be seen with a 10×hand-held magnifier or loop. Those responsiblefor diagnosing infestations should keepa few facts in mind about lice behavior andtransmission. Although lice can crawl relativelyquickly, they rarely travel far from apreferred habitat, such as the warmth of thescalp.2 They do not hop or fly. Lice clingtightly to the hair, but they may attempt toflee a heavily infested head and can befound in the individual's collar, hats, orother clothing worn near the head andneck.1 They are transferred to others primarilyby head-to-head contact, althoughfomites may sometimes carry lice. Licefound in brushes and combs are usuallyinjured or damaged and are less likely toinfest another individual.4 Children shouldbe taught to not share combs, brushes, orother items that touch the head, such asscarves, hats, headphones, or helmets.However, it is very important that childrenalways wear protective helmets when bicyclingor playing sports, even if the helmetmust be borrowed. The risk to a child from apotential head injury far outweighs any riskfrom head lice infestation. It is unlikely thatan infestation can be prevented, but transmissioncan be minimized if adults knowwarning signs of infestation and ensure thatchildren with lice are promptly treated.1

Treatments

Pediculosis capitis

OTC Preparations. Lice cause no medicalproblem, so treatment must be as safeas possible. From a pediatrician's point ofview, no amount of risk is acceptable. Treatmentoptions include pyrethroids such aspyrethrin and permethrin 1%. These productsare available over-the-counter (OTC)and are most likely to be used by parents ofchildren with lice. Available as shampoo orcrème rinse preparations, pyrethroids havelow mammalian toxicity and are generallyconsidered safe for most people. Pyrethroidsare not completely ovicidal, however, so asecond application is necessary within 7 to10 days.1 Resistance to pyrethroid productshas been documented and is discussedin greater detail in the article titled,"Clinical Update on Resistance and Treatmentof ," found in thissupplement.

Prescription Products. Permethrin 5%, aprescription product indicated for the treatmentof scabies, is also used by somephysicians to treat head lice. However, ifpermethrin 5% is prescribed because of atreatment failure of permethrin 1%, the childmight have permethrin-resistant head lice,and the 5% preparation will be no moreeffective than the 1% product.5

Lindane is an organochloride that hasrecently garnered attention because of itspoor safety profile. The Food and DrugAdministration (FDA) has warned of potentialcentral nervous system toxicity andincreased risk for seizures and has recommendedthat lindane be used with cautiononly in a select population.6 In addition tothese safety concerns, widespread lindaneresistance has been documented.7

Malathion 0.5% is an organophosphatethat has been reintroduced in the UnitedStates. Unlike other pediculicides, both OTCand prescription, the prescription productmalathion 0.5% is approximately 98% ovicidal,based on combined results of studiesconducted over the last 20 years. Also, noresistance to malathion 0.5% has beenreported to date.1,7 (Other malathion productsmarketed outside the United States havelower ovicidal activity and are associatedwith some resistance, depending on geographicalregion.) Malathion is highly effective,but the AAP guidelines note that thisproduct is a cholinesterase inhibitor, whichis associated with potential respiratorydepression if ingested. There are no reportsin the medical literature of respiratorydepression or poisoning associated with topicalmalathion. Another concern aboutmalathion is its flammable alcohol base.1Pediatricians worry about product labelinginstructions to leave malathion on the hairfor 8 to 12 hours, potentially prolonging riskfor the patient. However, no cases of burnsassociated with malathion have been reported.Researchers have found that malathionmay produce pediculicidal and ovicidal activitywithin minutes, so it may be possible touse this product effectively in less time,decreasing patient risk.7 As with all productsthat have a potential for toxicity in humans,and because of its flammability, malathionshould be used only under a physician's closesupervision. The AAP guidelines suggest theuse of malathion with extreme caution andonly when OTC products such as pyrethroidshave been ineffective.1,8

Other prescription products including theantibiotic cotrimoxazole and the anthelminticagent ivermectin are prescribed forsome cases of head lice infestation. Theseproducts are not approved as pediculicidesby the FDA. Cotrimoxazole is associatedwith risk for developing Stevens-Johnsonsyndrome, and ivermectin should not beadministered to children who weigh lessthan 15 kg.1

Preventing Pediculicide Resistance. Resistancehas been reported with all topicalpediculicides except malathion, significantlylimiting treatment options. Contributors toincreasing resistance include misdiagnosisand improper use of pediculicides. If a childis misdiagnosed as having lice, he or she willbe exposed unnecessarily to a pediculicide,also potentially making the product lesseffective if an infestation does occur.Improper use of pediculicides includesexcessive dilution if too much water is left inshampooed hair when the product is appliedand overuse or prophylactic use. Dilutedproducts are ineffective in killing lice andallow the parasite to develop resistance overtime from repeated exposure to sublethaldoses. Similarly, excessive use overexposesthe product, making it less effective overtime. An important question for pediatriciansto ask when evaluating a seeminglyintractable infestation is whether the patientmay be reinfesting by failing to remove liceor nits from the hair, clothing, or other itemsthat touch the head. If reinfestation occurs,that doesn't mean that products that failedin a first attempt will not work in the future.Live lice should be removed, and nits shouldbe removed if the treatment is not ovicidal.Pediculicide resistance should be confirmedbefore using a prescription product.1

"Natural" Remedies. Parents who believethat they can smother lice or otherwisedisrupt the respiratory system of the louseoften use occlusive agents. There is no scientificevidence to support the efficacy ofocclusive agents. Similarly, manual removalof lice, in the absence of other treatment, isunlikely to be effective because lice may bedifficult to find or may crawl away duringthe removal process.

School Control Measures

Routine screening for nits and lice is notan effective means of reducing the incidenceof infestation.1 Given the total amount oftime required to perform screenings, it is notthe best use of the school nurse's time.Other more important issues demand thenurse's attention, and the time children missfrom class for screening is not justified byresults. Considering the short amount oftime most nurses have to screen each child,often only 1 minute, the screening processgenerally is not thorough enough to be accurateand can provide a false sense of security.

Many school districts and some consumerorganizations, such as the National PediculosisAssociation, promote no-nit policies.These policies generally call for dismissal ofa child from school until all head lice, nits,and egg casings have been removed.9 Oftenthe child is sent home from school the day ofdiagnosis. Research suggests that a childwith an active head lice infestation is likelyto have had the infestation for at least amonth by the time it is discovered andtherefore poses no immediate risk on theday of diagnosis.1 Despite the assertion ofpromoters of no-nit policies that a nit couldhatch and spread to a child the same day itis discovered, hence the need to remove thechild from school immediately, there is nomedical evidence to support this position.The AAP recommends using common senseto assess each case. For example, a childwho has 2 live lice versus hundreds posesless risk. The child should be discouragedfrom close contact with other children, andparents should be notified and asked topromptly address the problem. In elementaryschools, an affected child's classmatesmay be notified that an infestation hasoccurred, but the child's confidentialityshould be protected.1

The AAP is working with school nurses todiscourage no-nit policies. Unfortunately,school nurses often are pressured by schooladministrators and parents to control infestations.The no-nit policies may appeal tolaypersons, and it is difficult to explain whythey are not effective, particularly whensome consumer organizations strongly supportthem. Nevertheless, there is no scientificbasis to confirm the effectiveness of suchprograms, but there is research supportingthe view that the presence of nits poses onlya slight risk. In a 2001 study conducted in 2metropolitan elementary schools, 1729 childrenwere screened for head lice. A total of28 children (1.6%) had lice, and 63 (3.6%)had nits with no lice. After 14 days, 18% ofchildren with nits alone developed lice.Researchers concluded that having 5 ormore nits within 1/4 inch of the scalpincreased the risk of conversion, but mostchildren with nits and no lice did notbecome infested. The study also concludedthat exclusionary policies for children withnits alone are excessive.10

Conclusion

Safe treatment of children with head liceinfestation is the primary objective of theAAP. Unfortunately, overuse and inappropriateuse of pediculicides may expose childrento unnecessary risk and contribute to resistance.Several pediculicides are available totreat head lice infestation, but resistance hasbeen documented for all products exceptmalathion. Prescription products should beused conservatively and only under closesupervision by a physician.

School measures that are designed tocontrol infestations may in fact be detrimental.Specifically, no-nit policies result in losttime from school, inappropriate allocation ofthe school nurse's time for screening, whichis often ineffective, and a response to infestationsthat is out of proportion to theirmedical significance. The AAP guidelines forcontrol of head lice infestation include recommendationsfor accurate diagnosis, safetreatment options, and a common-senseapproach to managing infestations in aschool environment.

Pediatrics.

1. Frankowski BL, Weiner LB; Committee on SchoolHealth the Committee on Infectious Diseases.American Academy of Pediatrics. Head lice. 2002;110:638-643.

2. Pollack RJ. Head lice information. Harvard School ofPublic Health. Available at: http://www.hsph.harvard.edu/headlice.html. Accessed on June 17, 2004.

3. Meinking T, Taplin D. Infestations. In: PediatricDermatology. 3rd ed. Schachner LA, Hansen RC, eds.Edinburgh: Mosby;2003:1141-1180.

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4. Chunge RN, Scott FE, Underwood JE, Zavarella KJ. Areview of the epidemiology, public health importance,treatment and control of head lice. 1991;82:196-200.

5. Treating Head Lice. Fact Sheet. Centers for DiseaseControl. Division of Parasitic Diseases. Available at:http://www.cdc.gov/ncidod/dpd/parasites/headlice/factsht_head_lice_treating.htm. Accessed on June 23,2004.

6. FDA Public Health Advisory: Safety of TopicalLindane Products for the Treatment of Scabies and Lice.Center for Drug Evaluation and Research. Available at:http://www.fda.gov/cder/drug/infopage/lindane/default.htm. Accessed on June 23, 2003.

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7. Meinking TL, Serrano L, Hard B, et al. Comparativein vitro pediculicidal efficacy of treatments in a resistanthead lice population in the United States. 2002;138:220-224.

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8. Hansen RC, and Working Group on the Treatment ofResistant Pediculosis. Guidelines for the treatment of resistantpediculosis. 2000;17(suppl):1-10.

9. The No Nit Policy. National Pediculosis Association.Available at: http://www.headlice.org/downloads/nonitpolicy.htm. Accessed on June 23, 2004.

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10. Williams LK, Reichert A, MacKenzie WR,Hightower AW, Blake PA. Lice, nits, and school policy. 2001;107:1011-1015.