SYNERGIZED PYRETHRIN MOUSSE, A NEW APPROACH TO HEAD LICE ERADICATION - EFFICACY IN-FIELD AND LABORATORY STUDIES

The purpose of this study was to evaluate the pediculicidal and ovicid al efficacy of a new, single-application formulation of synergized nat ural pyrethrins (presented in an aerosol mousse form) compared with an established, effective formulation based on permethrin (in a creme ri nse form). The trial was a single-blind, comparative, randomized, para llel-group study. Children between the ages 7 and 15 years and adults with active head lice infections, identified by the presence of live l ice, were enrolled from a school and a children's home in Dhaka, Bangl adesh. Prevalence of infection ranged from 75% to 100% in the two stud y centers. The field study confirmed laboratory findings showing pyret hrin mousse to be effective at killing both lice and their eggs with a single 10-minute application. Of 52 patients identified with lice, 42 were treated with pyrethrin mousse and 10 with permethrin creme rinse . In each case, a sample of viable louse eggs was taken from the patie nts' hair before and after treatment. The eggs were then incubated to assess ovicidal activity. After treatment, the patients were examined for lice on alternate days until day 8 and then again on day 14. None of the patients in either group was found to have lice up to 2 days af ter treatment. One patient was found to have two moribund hatchlings o n day 4. By day 6, when any eggs still present on the scalp would be e xpected to hatch, 19 pyrethrin mousse-treated patients were available for assessment. Two patients had been reinfected from contacts. No lic e were found at 14 days on the four pyrethrin mousse-treated patients available for assessment. No lice were found on creme rinse-treated su bjects. A significantly lower hatch rate was found in eggs sampled aft er pyrethrin mousse treatment than after treatment with permethrin cre me rinse (P < 0.01). Synergized pyrethrin mousse is effective as a ped iculicide and ovicide in one application.