Head lice are becoming increasingly resistant to conventional treatment (i.e., neurotoxic insecticides, household cleaning, and nit removal). Pearlman studied the efficacy of a dry-on, suffocation-based pediculicide (DSP) treatment, which is applied wet and blown dry-on the hair, enveloping the insect in a “shrink-wrapped” film.

The study involved two uncontrolled open trials. Inclusion criteria were active difficult-to-treat head lice infestation and failure to respond to or parental refusal to use conventional neurotoxins. Patients in both trials were provided with clean combs, brushes, clothing, and bedding, and were given a weekly DSP treatment until cured, or up to three applications. The nits were removed after DSP application using a nit comb in the first trial, but not in the second trial. Patients were considered cured if they experienced no increased scratching and itching, and there were no visible lice or nits after a wet combing test.

Of the 133 participants who completed the study, 120 were reevaluated after six months. One half of the patients were unresponsive to standard treatments before participating in the study. Trials 1 and 2 had similar cure rates (97 versus 95 percent) and long-term remission rates (94 versus 95 percent). Compared with patients in the second trial, those in the first trial had at least 100 times more nits removed during combing.

The author concludes that the rate of cure with DSP was high, and the rate of reinfestation after six months was low. Patients who did not respond after three applications were cured after a fourth application. Nit removal was not necessary in effecting cure.