Control Measures

* Cleanliness is important in preventing body louse infestations. The easiest control method of occasional infestations is to expose infested clothing to a minimum temperature of 70 degrees C for at least one hour. In emergency situations, it may be impractical or impossible for people to wash properly and fuel for heating water may be in short supply. In general, chemical control is required, especially where louse-borne disease threatens. Two application procedures may be used: the dusting technique (individual and/or mass treatment) and treating clothing. In view of the spread of insecticide resistance in body louse populations, the choice of insecticide for a campaign should be preceded by a survey of insecticide susceptibility status.

* Suitable insecticidal dusts for body louse control are permethrin (0.5%), temephos (2%), propoxur (1%) and carbaryl (5%). One thorough treatment of infested clothing with insecticide should be sufficient, although retreatments may be required at three to four week intervals if infestations persist or reinfestation is expected. Dusting is not recommended for people with dermatological problems or exposed wounds. The precautions on the insecticide label should be carefully followed. Where infestation is known to be widespread, systematic application of insecticide to all persons in the community is recommended.

* The process of treating clothing with insecticide is simple, cheap and affords protection for at least six weeks, even with repeated washings. This avoids the problem of repeated treatments in areas difficult to access regularly. The pyrethroid insecticide, permethrin, is recommended for impregnation and should be diluted with water to give an optimal target dose of 0.65-1 g/m2 on clothing.

* Louse-infested persons exposed to typhus fever should be kept under observation for 15 days after application of an insecticide with residual effect.

* All immediate contacts should be kept under surveillance for two weeks.

* If death from louse-borne typhus occurs before delousing, the clothing should be deloused by thorough application of an insecticide.

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