Elsevier

The Lancet

Volume 356, Issue 9229, 12 August 2000, Pages 540-544
The Lancet

Articles
Comparison of wet combing with malathion for treatment of head lice in the UK: a pragmatic randomised controlled trial

https://doi.org/10.1016/S0140-6736(00)02578-2Get rights and content

Summary

Background

Concern about the effectiveness and toxicity of insecticide lotions has led to promotion of mechanical methods to remove head lice. We compared the effectiveness of “bug-busting” (wet combing with a fine-toothed comb) and malathion lotion.

Methods

We screened 4037 schoolchildren in two counties in Wales, UK (intermediate resistance to malathion). Of 167 found to have head lice, 81 (aged 3–14 years) were eligible to participate in a randomised controlled trial that compared mechanical removal of lice by a commercial kit every 3–4 days for 2 weeks with two applications of 0·5% malathion lotion 7 days apart; parents carried out both treatments. The outcome measure was the presence of live lice 7 days after the end of treatment. Analyses were by intention to treat.

Findings

74 children completed the study and 72 were included in the analysis. The cure rate was 38% (12 of 32) for bug-busting and 78% (31 of 40) for malathion. Children assigned bug-busting were 2·8 (95% CI 1·5–5·2) times more likely than those assigned malathion to have lice at the end of treatment (p=0·0006).

Interpretation

Malathion lotion was twice as effective as bug-busting, even in an area with intermediate resistance. Policies advocating bug-busting as first-line treatment for head lice in the general population are inappropriate. Assessment of the outcome of treatment 1–2 weeks after completion is essential for successful management. Only about 50% of participants complied fully with treatment, so future trials should be pragmatic in design, avoid false incentives, and study representative samples of children.

Introduction

Mechanical removal of head lice by combing to control or eradicate infestation is not new, but during the past few years in the UK the “bug-busting” (Community Hygiene Concern, London, UK) wet-combing method has been promoted as a treatment for head lice in response to concerns about the effectiveness and potential toxicity of insecticide lotions.1 Bug-busting involves combing of wet hair with a fine-toothed comb every 3–4 days for 2 weeks (slightly longer than the maximum incubation period of lice eggs) to remove all lice as they hatch, ensuring that none reach maturity and lay the next generation of eggs. Public concern over the use of insecticides on children, an increase in resistance to the popular pyrethroid preparations, and a large rise in prescribing costs are additional pressures that contribute towards the increased use of mechanical methods of treatment.2, 3, 4, 5, 6, 7 The UK Department of Health has supported the use of the method, publishing a leaflet to demonstrate its use. Despite this support and the availability of a bug-buster kit, there have been no published trials of the method.8, 9

A recent Cochrane review of interventions for treatment of head lice called for trials of the bug-busting method.9 The reviewer also requested that trials of insecticide lotions be done in western populations infected with lice that may not be fully susceptible to the relevant insecticide so that the effectiveness of existing products can be accurately assessed. The only studies that met the rigorous inclusion criteria for that review had been carried out in populations in which insecticide lotions had never previously been used.10, 11, 12

We undertook a pragmatic trial, analysed by intention to treat, comparing the effectiveness of a commercial bug-busting kit with that of commercial 0·5% malathion lotion in a representative sample of children from an area with established intermediate resistance to malathion. This design provides an estimate of the effectiveness of each method in normal use by the general public.13

Section snippets

Participants

We selected a random sample of 24 primary schools (children aged 5–11 years) from the counties of Flintshire and Denbighshire in North Wales, where previous local studies of head lice, by standard laboratory methods, had identified intermediate resistance to malathion (lethal time 50% [LT50] by the method of Burgess 160 min).14, 15 Small rural schools (fewer than 40 pupils) in remote areas were excluded for logistical reasons. School nurses, following a standard protocol and using detection

Design

At the initial visit, we recorded baseline data on age, sex, the presence of asthma, scalp disorders, and presence of head lice. Data were collected on all household members (including adults who accepted examination) on the observed presence of lice, and which treatment was allocated. The participants were examined for the presence of lice on day 7 and then 7 days after the end of treatment (day 15 for most individuals in the malathion group, variable for bug-busting because the parent

Results

4037 children were screened in schools and 167 were referred (crude prevalence 4·1%). 134 were visited in the time available. 112 agreed to take part in the study (response rate 83·6%, figure). 36 children did not meet the inclusion criteria. Five siblings were included. 81 children started the study and were randomly assigned bug-busting (37) or malathion lotion (44).

74 children (91%) completed the study and received outcome visits. Six withdrew from the study (four from bug-busting and two

Discussion

We found that malathion was twice as effective as bug-busting in eradication of head lice.

This study was pragmatic and designed to give an estimate of the effect of different treatment policies rather than of potential benefit in children who received treatment exactly as planned. The participants were a random sample of the local population of children at primary schools and their siblings who were found to have head lice. The random sample recruitment and the high response rate suggest that

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