The Bug Buster kit was four times more effective than current over the counter pediculicides for eliminating head lice. This finding is contrary to a previous study in Wales in which malathion treatment was twice as effective as the Bug Buster regimen.10
It seems likely that the higher cure rate with the Bug Buster kit in our study is a result of improvements to the fine toothed comb, as this was the only major change. If so, it suggests that the success of fine toothed combing depends on the choice of comb. The effectiveness of the pediculicides was much lower in our trial than in the Welsh trial, and much more in line with the results from a previous trial in Bristol, which reported cure rates of 13% for permethrin and 36% for malathion.4
This discrepancy may be accounted for in several ways. Firstly, we used the manufacturer's recommended single dose of insecticide rather than two doses six days apart, which is now considered an unlicensed use.15
Owing to the limited residual effect, a double dose is likely to have greater success in killing nymphs that emerge from eggs not destroyed by the first dose. Secondly, our follow-up time was five days rather than seven days after insecticide treatment, as in the Welsh trial, but this is unlikely to have led to an underestimate of the cure rate given the lack of a significant residual effect. A longer period before measurement of outcomes increases the chance of nymphs emerging and being detected, and also increases the risk of reinfestation. Thirdly, we used an aqueous formulation rather than an alcohol one so that we could include people with allergies. The Welsh trial used either formulation, according to whether participants had allergies, but did not report any difference in effectiveness between the two. Fourthly, we recruited only people whose lice infestation had been reported by their families, rather than using school nurses to find cases by screening with fine toothed combs as in the Welsh trial. Our study population was reasonably representative of the population who normally seek treatment for head lice, as the ratio of those who had previously sought treatment from pharmacies or their doctors was similar to that reported in the national population.17
For several reasons we therefore believe our trial better reflects how over the counter products are used in the community.
Finally, the discrepancy may also be due to differences in resistance to insecticide, as our trial was carried out after the Welsh trial and included a range of urban settings. The particularly poor effectiveness of permethrin is likely to be due to widespread kdr-type resistance; all but one of the lice from treatment failures collected in this study were found to have the T929I and L932F resistant genotype mutations of the paratype sodium channel gene (MSW, unpublished data). On the basis of these and earlier similar findings we believe that the status of licensed insecticide treatments needs to be assessed as they potentially expose users to repeat applications without any important reduction in infestations.
The updated Bug Buster kit seems to provide a viable alternative to over the counter insecticide treatments. An observational study in Ghent, Belgium reported promising findings on satisfaction with wet combing as a treatment.18
In this study, families of head lice infested schoolchildren were given impartial advice on treatment options and then allowed to choose the treatment; most chose wet combing with conditioner (29%) over pediculicides (19%) or a combination of the two (15%), which suggests the Bug Buster regimen may be readily taken up by the community.
Some may consider that the cure rate of only 57% we detected with the Bug Buster kit is still unacceptable and may not provide an efficient treatment against head lice. At present there are no readily available products that provide fully effective control of head lice, and there is an urgent need to identify safe, novel insecticides of proved efficacy.
What is already known on this topic
Head lice have varying degrees of resistance to over the counter pediculicides
Fine tooth combing of wet hair is an effective method of detecting head lice but unproved as a treatment
What this study adds
Effectiveness of popular over the counter pediculicides for eliminating head lice is poor
The kdr-type resistance mechanism to pyrethroids is widespread in head lice in the United Kingdom
The Bug Buster kit is significantly more effective than common over the counter pediculicides for normal unsupervised use