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PEDIATRICS Vol. 108 No. 6 December 2001, pp. 1393
Head Lice Infestation: Single Drug Versus Combination Therapy
To the Editor—Hipolito et al1 reported their interesting observations on the efficacy of 3 treatments for head louse infestations (HLIs), and made specific recommendations for combined treatment with 1% permethrin and trimethoprim/sulfamethoxazole (TMP/SMX). Several problems are evident in their methodology and interpretation, however, and their choice of therapy may be inappropriate.
The diagnostic criteria the authors used for HLIs included the presence of lice (adults or nymphs) or eggs (nits), and the outcome was assessed either by the investigators or by the parents or caregivers. The authors report using a magnifying glass to distinguish a "true viable egg with an empty egg." Because health care professionals and nonspecialists frequently fail to distinguish bona fide eggs from unrelated debris, and viable from nonviable (dead or hatched) eggs, the presence of eggs is not indicative of an active infestation.2 Furthermore, we suggest that a standard magnifying glass would generally provide insufficient magnification to allow for a precise determination of egg viability. The correct identification of nymphal and adult lice is also problematic.1 Parents and caretakers were asked to comb the participant’s hair, but the authors report the type of comb differed between treatment groups, and even within one group. It is not clear, therefore, whether the reported reduction in prevalence was attributable to the administered agent, the type of comb used, or the basis for assessing outcome.
Most troubling is their recommendation for using TMP/SMX for HLIs, even if limited to cases of suspected resistance to pediculicides. Health care providers and parents frequently presume head lice to be resistant to current pediculicides, and may, therefore, more often consider the use of TMP/SMX for HLIs. Such a use of this drug may, however, unnecessarily promote bacterial resistance and further reduce its value as an antibiotic.3
The authors provided an incomplete list of current FDA-registered pediculicides. In addition to lindane, permethrin, and synergized pyrethrins, they failed to mention malathion lotion. Finally, although some resistance to permethrin in the United States has now been documented,4 permethrin and synergized pyrethrins may remain the pediculicides of choice for newly recognized louse infestations.
Richard J. Pollack, PhD
Department of Immunology and Infectious Diseases
Harvard School of Public Health
Boston, MA 02115
PEDIATRICS (ISSN 1098-4275). ©2001 by the American Academy of Pediatrics
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