Medical Microbiology

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persons,etc.Childrenandwomenaremostfrequentlyinfested.About 60 %

ofpersonswithliceshowlowlevelsofinfestationwith< 10 adultlice,the

othershigherlevels(upto> 1000 lice).Accordingtoofficialstatistics,

headlouseinfestationintheUKincreasedbetween 1971 and 1991 about

sevenfold;in 1997 ,about 1 8.7%oftheschoolchildreninBristolwereinfested

withlice.

Transmissionisinmostcasesbypersonalcontact(mother-childcontacts,

childrenplaying,etc.),butcanalsobemediatedbysuchobjectsascombs,

caps,pillows,headsupports,stuffedanimals,etc.

Clinicalmanifestations

&Pruritusandexcoriationsinthescalparea,nitsonhairs,especiallyinthe

retroauriculararea.

&Insomecasesscalpdermatitis,especiallyatthenuchalhairline:small

papules,moistexanthema,andcrusting.

&Occasionallyalsogeneralizeddermatitisonotherpartsofthebodycaused

byallergicreactionstolouseantigens.

&Bothobjectiveandsubjectivesymptomsmaybelackinginupto 20 %of

cases.

Diagnosis.Determinationofsymptomsanddetection(directorwithmagni-

fier)ofliceand/ornits,especiallyaroundthetemples,ears,andneck.

Itisimportanttoclarifytheepidemiologicalbackgroundregardingall

possiblesourcesofinfestation(e.g.,inschools).Somecountrieshaveintro-

ducedregulationsoncontrolofoutbreaksoflouseinfestationinschoolsand

othercommunityinstitutions.

Therapy.Ingroupoutbreaks,allcontactpersonsmustbetreatedconcur-

rently,e.g.,entireschoolclassesandthefamiliesofinfestedchildren.Avari-

etyofdifferentinsecticidesareavailablefortherapy,forinstancepyrethrum,

permethrin, malathion, andc-hexachlorocyclohexane(c-HCH, lindane).

(Important:licemayshowresistancetocertaininsecticides!)Followthe

preparationapplicationinstructionsandrepeatapplicationaftersevento

10 days.Rinsingthehairwith 5 %vinegarinwaterfollowedbymechanical

removalofthenitswitha“lousecomb”isasupportivemeasure.

Control.Clothing,pillows,etc.thathavebeenincontactwithlicemustbe

decontaminated:washlaundryat 608 C;keepclothesandotherobjectsin

plasticbagssealedwithadhesivetapeforfourweeksordeep-freezethe

bagsforonedayat–1 0 to–1 58 C.Cleanupholsteredfurniture,mattresses,

etc.thoroughlywithavacuumcleaneranddecontaminateasnecessary(con-

sultanexpertforpestcontrol).

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Kayser, Medical Microbiology © 2005 Thieme