Interest in mechanical treatment of head lice has been stimulated by concerns about the potential toxicity of insecticides and the development of insecticide resistance. In Great Britain, the technique of “bug-busting,” or wet-combing the hair every three to four days for two weeks, has become a popular therapy. Roberts and colleagues compared the effectiveness of this therapy with treatment using 0.5 percent malathion lotion.

More than 4,000 children five to 11 years of age and attending 24 schools in north Wales were screened for inclusion in the study. If lice were identified, a nurse visited the home to assess household contacts and provide instruction in treatment. During this visit, data about the child and other household members were collected. Infested children were randomly assigned to treatment with malathion or a bug-busting kit. The kit contained instructions and equipment for wet-combing every three to four days for two weeks. Malathion was applied for eight to 10 hours, and the treatment was repeated after seven days. Children were assessed for lice infestation seven days after completing the assigned treatment.

The mean age of participants was 7.7 years, and the 51 girls and 21 boys were equally distributed between the treatment groups. Thirty-two of the 37 children assigned to bug-busting completed the trial, and the cure rate was 38 percent. In 42 of the 44 children assigned to malathion treatment who completed the trial, the cure rate was 78 percent. No adverse effects of malathion treatment were detected, but one family complained of a strong smell from the original lotion. Good compliance with treatment was recorded by 47 percent of the bug-busting group and 53 percent of the malathion group. Most compliance issues were small changes in the timing of treatments.

The authors conclude that malathion lotion was twice as effective as mechanical combing in removing head lice. Resistance to malathion was estimated to be “intermediate” in the area studied. The authors do not recommend that mechanical bug-busting techniques be promoted as adequate first-line therapy for head lice, and they stress the need for treatments that are easy to use and likely to result in high compliance.