and fomites play minor roles in lice transmission. 23,28 There is now growing evidence that viable, conta- gious, head lice are rarely found in the environment; therefore, cleaning efforts aimed at removing them are of minimal usefulness. 15,29 – 31 There is no well- documented study showing that extensive cleaning measures are required for or even contribute to cur- ing head lice. The simplicity of this method was welcomed by both parents and children. Parents reported that head lice treatment without nit removal and without extensive household cleaning was not an over- whelming burden. Caregivers reported that children were much more cooperative during treatment with a plain comb than they had been during their pre- study treatment with a fine nit comb. Although the lotion must be left in place for at least 8 hours to be effective, in practice it typically was left in place for 24 hours, until the next day ’ s bath. Patients typi- cally underwent application 1 day, attended school the next morning with it dry in their hair, and waited until bath time the next day to remove it by washing their hair with their usual shampoo. After the DSP lotion was dried in the scalp, the lotion was not visible, and the hair could be styled as usual. Treated children went to school with their hair looking the same as usual. These results suggest that a DSP lotion can offer a solution to the widespread reports of head lice that are resistant to conventional pediculicides. The ma- jority of patients in this trial reported their lice to be resistant to a wide variety of conventional and alter- native pediculicides (Table 1), but these patients were cured with the DSP lotion. The 5 patients who were not cured with the 3 applications allowed in the protocol were all cured by completing a total of 4 applications. There were no cases of DSP treatment failure in this study. DSP lotions may not be hampered by the evolution of drug-resistant lice, as would be expected for neu- rotoxic pediculicides. 32 The latter agents act by tar- geting a specific molecule. If that molecule is mu- tated, then the louse becomes resistant to the neurotoxic pediculicide. Table 4 shows the decrease in neurotoxic pediculicide cure rates as reports of drug-resistant lice have appeared. DSP lotions target the entire exterior of the louse, by coating the louse and mechanically blocking the spiracles (breathing holes). Development of resistance would require complex changes in the breathing mechanism itself and would be unlikely to occur. ACKNOWLEDGMENTS LiceMeister combs used in this study were do- nated by the National Pediculosis Association. I thank the physicians and nurses of the following institutions for referring patients to participate in this study: Welch Road Pediatrics Group (Palo Alto, CA), Lucile Packard Hospital for Children at Stanford University Medical Center (Stanford, CA), Menlo Medical Clinic Department of Pediatrics (Menlo Park, CA), Palo Alto Medical Foundation Depart- ment of Pediatrics (Palo Alto, CA), and Kaiser Hos- pital Department of Pediatrics (Redwood City, CA).
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- Fall '19
- Test, Head louse, Pediculosis, Body louse, Louse, Treatment of human head lice, Head-louse infestation